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Chapter 8. Client and Utility Programs
There are many different MySQL client programs that connect to the
server to access databases or perform administrative tasks. Other
utilities are available as well. These do not establish a client
connection with the server but perform MySQL-related operations.
This chapter provides a brief overview of these programs and then a
more detailed description of each one. Each program's description
indicates its invocation syntax and the options that it understands.
See Chapter 4, Using MySQL Programs, for general information
on invoking programs and specifying program options.
8.1. Overview of Client and Utility Programs
The following list briefly describes the MySQL client programs and
utilities:
myisamchk
A utility to describe, check, optimize, and repair
MyISAM tables. See
Section 8.2, “myisamchk — MyISAM Table-Maintenance Utility”.
myisamlog
A utility that processes the contents of a
MyISAM log file. See
Section 8.4, “myisampack — Generate Compressed, Read-Only MyISAM Tables”.
myisampack
A utility that compresses MyISAM tables to
produce smaller read-only tables. See
Section 8.4, “myisampack — Generate Compressed, Read-Only MyISAM Tables”.
mysql
The command-line tool for interactively entering SQL
statements or executing them from a file in batch mode. See
Section 8.5, “mysql — The MySQL Command-Line Tool”.
mysqlaccess
A script that checks the access privileges for a hostname,
username, and database combination. See
Section 8.6, “mysqlaccess — Client for Checking Access Privileges”.
mysqladmin
A client that performs administrative operations, such as
creating or dropping databases, reloading the grant tables,
flushing tables to disk, and reopening log files.
mysqladmin can also be used to retrieve
version, process, and status information from the server. See
Section 8.7, “mysqladmin — Client for Administering a MySQL Server”.
mysqlbinlog
A utility for reading statements from a binary log. The log of
executed statements contained in the binary log files can be
used to help recover from a crash. See
Section 8.8, “mysqlbinlog — Utility for Processing Binary Log Files”.
mysqlcheck
A table-maintenance client that checks, repairs, analyzes, and
optimizes tables. See Section 8.9, “mysqlcheck — A Table Maintenance and Repair Program”.
mysqldump
A client that dumps a MySQL database into a file as SQL
statements or as tab-separated text files. See
Section 8.10, “mysqldump — A Database Backup Program”.
mysqlhotcopy
A utility that quickly makes backups of
MyISAM tables while the server is running.
See Section 8.11, “mysqlhotcopy — A Database Backup Program”.
mysqlimport
A client that imports text files into their respective tables
using LOAD DATA INFILE. See
Section 8.12, “mysqlimport — A Data Import Program”.
mysqlshow
A client that displays information about databases, tables,
columns, and indexes. See Section 8.13, “mysqlshow — Display Database, Table, and Column Information”.
mysql_zap
A utility that kills processes that match a pattern.
Section 8.14, “mysql_zap — Kill Processes That Match a Pattern”.
perror
A utility that displays the meaning of system or MySQL error
codes. See Section 8.15, “perror — Explain Error Codes”.
replace
A utility program that performs string replacement in the
input text. See Section 8.16, “replace — A String-Replacement Utility”.
MySQL AB also provides a number of GUI tools for administering and
otherwise working with MySQL servers. For basic information about
these, see Chapter 4, Using MySQL Programs.
Each MySQL program takes many different options. Most programs
provide a --help option that you can use to get a
full description of the program's different options. For example,
try mysql --help.
MySQL client programs that communicate with the server using the
MySQL client/server library use the following environment
variables:
Use of MYSQL_PWD is insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
You can override the default option values or values specified in
environment variables for all standard programs by specifying
options in an option file or on the command line. See
Section 4.3, “Specifying Program Options”.
8.2. myisamchk — MyISAM Table-Maintenance Utility
The myisamchk utility gets information
about your database tables or checks, repairs, or optimizes
them. myisamchk works with
MyISAM tables (tables that have
.MYD and .MYI files
for storing data and indexes).
Invoke myisamchk like this:
shell> myisamchk [options] tbl_name ...
The options specify what you want
myisamchk to do. They are described in the
following sections. You can also get a list of options by
invoking myisamchk --help.
With no options, myisamchk simply checks
your table as the default operation. To get more information
or to tell myisamchk to take corrective
action, specify options as described in the following
discussion.
tbl_name is the database table you
want to check or repair. If you run
myisamchk somewhere other than in the
database directory, you must specify the path to the database
directory, because myisamchk has no idea
where the database is located. In fact,
myisamchk doesn't actually care whether the
files you are working on are located in a database directory.
You can copy the files that correspond to a database table
into some other location and perform recovery operations on
them there.
You can name several tables on the
myisamchk command line if you wish. You can
also specify a table by naming its index file (the file with
the .MYI suffix). This allows you to
specify all tables in a directory by using the pattern
*.MYI. For example, if you are in a
database directory, you can check all the
MyISAM tables in that directory like this:
shell> myisamchk *.MYI
If you are not in the database directory, you can check all
the tables there by specifying the path to the directory:
shell> myisamchk /path/to/database_dir/*.MYI
You can even check all tables in all databases by specifying a
wildcard with the path to the MySQL data directory:
shell> myisamchk /path/to/datadir/*/*.MYI
The recommended way to quickly check all
MyISAM tables is:
shell> myisamchk --silent --fast /path/to/datadir/*/*.MYI
If you want to check all MyISAM tables and
repair any that are corrupted, you can use the following
command:
shell> myisamchk --silent --force --fast --update-state \
--key_buffer_size=64M --sort_buffer_size=64M \
--read_buffer_size=1M --write_buffer_size=1M \
/path/to/datadir/*/*.MYI
This command assumes that you have more than 64MB free. For
more information about memory allocation with
myisamchk, see
Section 8.2.5, “myisamchk Memory Usage”.
You must ensure that no other program is using the tables
while you are running myisamchk. Otherwise,
when you run myisamchk, it may display the
following error message:
warning: clients are using or haven't closed the table properly
This means that you are trying to check a table that has been
updated by another program (such as the
mysqld server) that hasn't yet closed the
file or that has died without closing the file properly.
If mysqld is running, you must force it to
flush any table modifications that are still buffered in
memory by using FLUSH TABLES. You should
then ensure that no one is using the tables while you are
running myisamchk. The easiest way to avoid
this problem is to use CHECK TABLE instead
of myisamchk to check tables.
8.2.1. myisamchk General Options
The options described in this section can be used for any type
of table maintenance operation performed by
myisamchk. The sections following this one
describe options that pertain only to specific operations,
such as table checking or repairing.
--help, -?
Display a help message and exit.
--debug=debug_options,
-# debug_options
Write a debugging log. The
debug_options string often is
'd:t:o,file_name'.
--silent, -s
Silent mode. Write output only when errors occur. You can
use -s twice (-ss) to
make myisamchk very silent.
--verbose, -v
Verbose mode. Print more information about what the
program does. This can be used with -d
and -e. Use -v multiple
times (-vv, -vvv) for
even more output.
--version, -V
Display version information and exit.
--wait, -w
Instead of terminating with an error if the table is
locked, wait until the table is unlocked before
continuing. Note that if you are running
mysqld with external locking disabled,
the table can be locked only by another
myisamchk command.
You can also set the following variables by using
--var_name=value
syntax:
The possible myisamchk variables and their
default values can be examined with myisamchk
--help:
sort_buffer_size is used when the keys are
repaired by sorting keys, which is the normal case when you
use --recover.
key_buffer_size is used when you are
checking the table with --extend-check or
when the keys are repaired by inserting keys row by row into
the table (like when doing normal inserts). Repairing through
the key buffer is used in the following cases:
You use --safe-recover.
The temporary files needed to sort the keys would be more
than twice as big as when creating the key file directly.
This is often the case when you have large key values for
CHAR, VARCHAR, or
TEXT columns, because the sort
operation needs to store the complete key values as it
proceeds. If you have lots of temporary space and you can
force myisamchk to repair by sorting,
you can use the --sort-recover option.
Repairing through the key buffer takes much less disk space
than using sorting, but is also much slower.
If you want a faster repair, set the
key_buffer_size and
sort_buffer_size variables to about 25% of
your available memory. You can set both variables to large
values, because only one of them is used at a time.
myisam_block_size is the size used for
index blocks.
stats_method influences how
NULL values are treated for index
statistics collection when the --analyze
option is given. It acts like the
myisam_stats_method system variable. For
more information, see the description of
myisam_stats_method in
Section 5.2.2, “Server System Variables”, and
Section 7.4.7, “MyISAM Index Statistics Collection”. For MySQL
5.0, stats_method was added in
MySQL 5.0.14. For older versions, the statistics collection
method is equivalent to nulls_equal.
ft_min_word_len and
ft_max_word_len indicate the minimum and
maximum word length for FULLTEXT indexes.
ft_stopword_file names the stopword file.
These need to be set under the following circumstances.
If you use myisamchk to perform an
operation that modifies table indexes (such as repair or
analyze), the FULLTEXT indexes are rebuilt
using the default full-text parameter values for minimum and
maximum word length and the stopword file unless you specify
otherwise. This can result in queries failing.
The problem occurs because these parameters are known only by
the server. They are not stored in MyISAM
index files. To avoid the problem if you have modified the
minimum or maximum word length or the stopword file in the
server, specify the same ft_min_word_len,
ft_max_word_len, and
ft_stopword_file values to
myisamchk that you use for
mysqld. For example, if you have set the
minimum word length to 3, you can repair a table with
myisamchk like this:
shell> myisamchk --recover --ft_min_word_len=3 tbl_name.MYI
To ensure that myisamchk and the server use
the same values for full-text parameters, you can place each
one in both the [mysqld] and
[myisamchk] sections of an option file:
[mysqld]
ft_min_word_len=3
[myisamchk]
ft_min_word_len=3
An alternative to using myisamchk is to use
the REPAIR TABLE, ANALYZE
TABLE, OPTIMIZE TABLE, or
ALTER TABLE. These statements are performed
by the server, which knows the proper full-text parameter
values to use.
8.2.2. myisamchk Check Options
myisamchk supports the following options
for table checking operations:
--check, -c
Check the table for errors. This is the default operation
if you specify no option that selects an operation type
explicitly.
--check-only-changed, -C
Check only tables that have changed since the last check.
--extend-check, -e
Check the table very thoroughly. This is quite slow if the
table has many indexes. This option should only be used in
extreme cases. Normally, myisamchk or
myisamchk --medium-check should be able
to determine whether there are any errors in the table.
If you are using --extend-check and have
plenty of memory, setting the
key_buffer_size variable to a large
value helps the repair operation run faster.
--fast, -F
Check only tables that haven't been closed properly.
--force, -f
Do a repair operation automatically if
myisamchk finds any errors in the
table. The repair type is the same as that specified with
the --recover or -r
option.
--information, -i
Print informational statistics about the table that is
checked.
--medium-check, -m
Do a check that is faster than an
--extend-check operation. This finds only
99.99% of all errors, which should be good enough in most
cases.
--read-only, -T
Don't mark the table as checked. This is useful if you use
myisamchk to check a table that is in
use by some other application that doesn't use locking,
such as mysqld when run with external
locking disabled.
--update-state, -U
Store information in the .MYI file to
indicate when the table was checked and whether the table
crashed. This should be used to get full benefit of the
--check-only-changed option, but you
shouldn't use this option if the mysqld
server is using the table and you are running it with
external locking disabled.
8.2.3. myisamchk Repair Options
myisamchk supports the following options
for table repair operations:
--backup, -B
Make a backup of the .MYD file as
file_name-time.BAK
--character-sets-dir=path
The directory where character sets are installed. See
Section 5.11.1, “The Character Set Used for Data and Sorting”.
--correct-checksum
Correct the checksum information for the table.
--data-file-length=len,
-D len
Maximum length of the data file (when re-creating data
file when it is “full”).
--extend-check, -e
Do a repair that tries to recover every possible row from
the data file. Normally, this also finds a lot of garbage
rows. Don't use this option unless you are desperate.
--force, -f
Overwrite old intermediate files (files with names like
tbl_name.TMD
--keys-used=val,
-k val
For myisamchk, the option value is a
bit-value that indicates which indexes to update. Each
binary bit of the option value corresponds to a table
index, where the first index is bit 0. An option value of
0 disables updates to all indexes, which can be used to
get faster inserts. Deactivated indexes can be reactivated
by using myisamchk -r.
--max-record-length=len
Skip rows larger than the given length if
myisamchk cannot allocate memory to
hold them.
--parallel-recover, -p
Uses the same technique as -r and
-n, but creates all the keys in parallel,
using different threads. This is beta-quality
code. Use at your own risk!
--quick, -q
Achieve a faster repair by not modifying the data file.
You can specify this option twice to force
myisamchk to modify the original data
file in case of duplicate keys.
--recover, -r
Do a repair that can fix almost any problem except unique
keys that aren't unique (which is an extremely unlikely
error with MyISAM tables). If you want
to recover a table, this is the option to try first. You
should try --safe-recover only if
myisamchk reports that the table can't
be recovered using --recover. (In the
unlikely case that --recover fails, the
data file remains intact.)
If you have lots of memory, you should increase the value
of sort_buffer_size.
--safe-recover, -o
Do a repair using an old recovery method that reads
through all rows in order and updates all index trees
based on the rows found. This is an order of magnitude
slower than --recover, but can handle a
couple of very unlikely cases that
--recover cannot. This recovery method
also uses much less disk space than
--recover. Normally, you should repair
first with --recover, and then with
--safe-recover only if
--recover fails.
If you have lots of memory, you should increase the value
of key_buffer_size.
--set-character-set=name
Change the character set used by the table indexes. This
option was replaced by --set-collation in
MySQL 5.0.3.
--set-collation=name
Specify the collation to use for sorting table indexes.
The character set name is implied by the first part of the
collation name. This option was added in MySQL 5.0.3.
--sort-recover, -n
Force myisamchk to use sorting to
resolve the keys even if the temporary files would be very
large.
--tmpdir=path,
-t path
Path of the directory to be used for storing temporary
files. If this is not set, myisamchk
uses the value of the TMPDIR
environment variable. tmpdir can be set
to a list of directory paths that are used successively in
round-robin fashion for creating temporary files. The
separator character between directory names is the colon
(‘:’) on Unix and the
semicolon (‘;’) on Windows,
NetWare, and OS/2.
--unpack, -u
Unpack a table that was packed with
myisampack.
8.2.4. Other myisamchk Options
myisamchk supports the following options
for actions other than table checks and repairs:
--analyze, -a
Analyze the distribution of key values. This improves join
performance by enabling the join optimizer to better
choose the order in which to join the tables and which
indexes it should use. To obtain information about the key
distribution, use a myisamchk --description
--verbose tbl_name
command or the SHOW INDEX FROM
tbl_name statement.
--block-search=[offset],
-b offset
Find the record that a block at the given offset belongs
to.
--description, -d
Print some descriptive information about the table.
--set-auto-increment[=value],
-A[value]
Force AUTO_INCREMENT numbering for new
records to start at the given value (or higher, if there
are existing records with
AUTO_INCREMENT values this large). If
value is not specified,
AUTO_INCREMENT numbers for new records
begin with the largest value currently in the table, plus
one.
--sort-index, -S
Sort the index tree blocks in high-low order. This
optimizes seeks and makes table scans that use indexes
faster.
--sort-records=N,
-R N
Sort records according to a particular index. This makes
your data much more localized and may speed up range-based
SELECT and ORDER BY
operations that use this index. (The first time you use
this option to sort a table, it may be very slow.) To
determine a table's index numbers, use SHOW
INDEX, which displays a table's indexes in the
same order that myisamchk sees them.
Indexes are numbered beginning with 1.
If keys are not packed (PACK_KEYS=0)),
they have the same length, so when
myisamchk sorts and moves records, it
just overwrites record offsets in the index. If keys are
packed (PACK_KEYS=1),
myisamchk must unpack key blocks first,
then re-create indexes and pack the key blocks again. (In
this case, re-creating indexes is faster than updating
offsets for each index.)
8.2.5. myisamchk Memory Usage
Memory allocation is important when you run
myisamchk. myisamchk
uses no more memory than its memory-related variables are set
to. If you are going to use myisamchk on
very large tables, you should first decide how much memory you
want it to use. The default is to use only about 3MB to
perform repairs. By using larger values, you can get
myisamchk to operate faster. For example,
if you have more than 32MB RAM, you could use options such as
these (in addition to any other options you might specify):
shell> myisamchk --sort_buffer_size=16M --key_buffer_size=16M \
--read_buffer_size=1M --write_buffer_size=1M ...
Using --sort_buffer_size=16M should probably
be enough for most cases.
Be aware that myisamchk uses temporary
files in TMPDIR. If
TMPDIR points to a memory filesystem, you
may easily get out of memory errors. If this happens, run
myisamchk with the
--tmpdir=path
option to specify some directory located on a filesystem that
has more space.
When repairing, myisamchk also needs a lot
of disk space:
Double the size of the data file (the original file and a
copy). This space is not needed if you do a repair with
--quick; in this case, only the index
file is re-created. This space is needed on the same
filesystem as the original data file! (The copy is created
in the same directory as the original.)
Space for the new index file that replaces the old one.
The old index file is truncated at the start of the repair
operation, so you usually ignore this space. This space is
needed on the same filesystem as the original index file!
When using --recover or
--sort-recover (but not when using
--safe-recover), you need space for a
sort buffer. The following formula yields the amount of
space required:
(largest_key + row_pointer_length) × number_of_rows × 2
You can check the length of the keys and the
row_pointer_length with
myisamchk -dv
tbl_name. This space
is allocated in the temporary directory (specified by
TMPDIR or
--tmpdir=path).
If you have a problem with disk space during repair, you can
try --safe-recover instead of
--recover.
8.3. myisamlog — Display MyISAM Log File Contents
myisamlog processes the contents of a
MyISAM log file.
Invoke myisamlog like this:
shell> myisamlog [options] [log_file [tbl_name] ...]
The default operation is update (-u). If a
recovery is done (-r), all writes and
possibly updates and deletes are done and errors are only
counted. The default log file name is
myisam.log if no
log_file argument is given, If
tables are named on the command line, only those tables are
updated.
myisamlog understands the following
options:
-?, -I
Display a help message and exit.
-c N
Execute only N commands.
-f N
Specify the maximum number of open files.
-i
Display extra information before exiting.
-o offset
Specify the starting offset.
-p N
Remove N components from path.
-r
Perform a recovery operation.
-R record_pos_file
record_pos
Specify record position file and record position.
-u
Perform an update operation.
-v
Verbose mode. Print more output about what the program
does. This option can be given multiple times to produce
more and more output.
-w write_file
Specify the write file.
-V
Display version information.
8.4. myisampack — Generate Compressed, Read-Only MyISAM Tables
The myisampack utility compresses
MyISAM tables.
myisampack works by compressing each column
in the table separately. Usually,
myisampack packs the data file 40%-70%.
When the table is used later, the server reads into memory the
information needed to decompress columns. This results in much
better performance when accessing individual rows, because you
only have to uncompress exactly one row.
MySQL uses mmap() when possible to perform
memory mapping on compressed tables. If
mmap() does not work, MySQL falls back to
normal read/write file operations.
Please note the following:
If the mysqld server was invoked with
external locking disabled, it is not a good idea to invoke
myisampack if the table might be
updated by the server during the packing process. It is
safest to compress tables with the server stopped.
After packing a table, it becomes read-only. This is
generally intended (such as when accessing packed tables
on a CD). Allowing writes to a packed table is on our TODO
list, but with low priority.
myisampack can pack
BLOB or TEXT
columns. (The older pack_isam program
for ISAM tables did not have this
capability.)
Invoke myisampack like this:
shell> myisampack [options] file_name ...
Each filename argument should be the name of an index
(.MYI) file. If you are not in the
database directory, you should specify the pathname to the
file. It is permissible to omit the .MYI
extension.
After you compress a table with myisampack,
you should use myisamchk -rq to rebuild its
indexes. Section 8.2, “myisamchk — MyISAM Table-Maintenance Utility”.
myisampack supports the following options:
--help, -?
Display a help message and exit.
--backup, -b
Make a backup of each table's data file using the name
tbl_name.OLD
--character-sets-dir=path
The directory where character sets are installed. See
Section 5.11.1, “The Character Set Used for Data and Sorting”.
--debug[=debug_options],
-#
[debug_options]
Write a debugging log. The
debug_options string often is
'd:t:o,file_name'.
--force, -f
Produce a packed table even if it becomes larger than the
original or if the intermediate file from an earlier
invocation of myisampack exists.
(myisampack creates an intermediate
file named
tbl_name.TMD.TMD file might not be deleted.)
Normally, myisampack exits with an
error if it finds that
tbl_name.TMD--force,
myisampack packs the table anyway.
--join=big_tbl_name,
-j
big_tbl_name
Join all tables named on the command line into a single
table big_tbl_name. All tables
that are to be combined must have
identical structure (same column names and types, same
indexes, and so forth).
--packlength=len,
-p len
Specify the row length storage size, in bytes. The value
should be 1, 2, or 3. myisampack stores
all rows with length pointers of 1, 2, or 3 bytes. In most
normal cases, myisampack can determine
the correct length value before it begins packing the
file, but it may notice during the packing process that it
could have used a shorter length. In this case,
myisampack prints a note that you could
use a shorter row length the next time you pack the same
file.
--silent, -s
Silent mode. Write output only when errors occur.
--test, -t
Do not actually pack the table, just test packing it.
--tmpdir=path,
-T path
Use the named directory as the location where
myisamchk creates temporary files.
--verbose, -v
Verbose mode. Write information about the progress of the
packing operation and its result.
--version, -V
Display version information and exit.
--wait, -w
Wait and retry if the table is in use. If the
mysqld server was invoked with external
locking disabled, it is not a good idea to invoke
myisampack if the table might be
updated by the server during the packing process.
The following sequence of commands illustrates a typical table
compression session:
shell> ls -l station.*
-rw-rw-r-- 1 monty my 994128 Apr 17 19:00 station.MYD
-rw-rw-r-- 1 monty my 53248 Apr 17 19:00 station.MYI
-rw-rw-r-- 1 monty my 5767 Apr 17 19:00 station.frm
shell> myisamchk -dvv station
MyISAM file: station
Isam-version: 2
Creation time: 1996-03-13 10:08:58
Recover time: 1997-02-02 3:06:43
Data records: 1192 Deleted blocks: 0
Datafile parts: 1192 Deleted data: 0
Datafile pointer (bytes): 2 Keyfile pointer (bytes): 2
Max datafile length: 54657023 Max keyfile length: 33554431
Recordlength: 834
Record format: Fixed length
table description:
Key Start Len Index Type Root Blocksize Rec/key
1 2 4 unique unsigned long 1024 1024 1
2 32 30 multip. text 10240 1024 1
Field Start Length Type
1 1 1
2 2 4
3 6 4
4 10 1
5 11 20
6 31 1
7 32 30
8 62 35
9 97 35
10 132 35
11 167 4
12 171 16
13 187 35
14 222 4
15 226 16
16 242 20
17 262 20
18 282 20
19 302 30
20 332 4
21 336 4
22 340 1
23 341 8
24 349 8
25 357 8
26 365 2
27 367 2
28 369 4
29 373 4
30 377 1
31 378 2
32 380 8
33 388 4
34 392 4
35 396 4
36 400 4
37 404 1
38 405 4
39 409 4
40 413 4
41 417 4
42 421 4
43 425 4
44 429 20
45 449 30
46 479 1
47 480 1
48 481 79
49 560 79
50 639 79
51 718 79
52 797 8
53 805 1
54 806 1
55 807 20
56 827 4
57 831 4
shell> myisampack station.MYI
Compressing station.MYI: (1192 records)
- Calculating statistics
normal: 20 empty-space: 16 empty-zero: 12 empty-fill: 11
pre-space: 0 end-space: 12 table-lookups: 5 zero: 7
Original trees: 57 After join: 17
- Compressing file
87.14%
Remember to run myisamchk -rq on compressed tables
shell> ls -l station.*
-rw-rw-r-- 1 monty my 127874 Apr 17 19:00 station.MYD
-rw-rw-r-- 1 monty my 55296 Apr 17 19:04 station.MYI
-rw-rw-r-- 1 monty my 5767 Apr 17 19:00 station.frm
shell> myisamchk -dvv station
MyISAM file: station
Isam-version: 2
Creation time: 1996-03-13 10:08:58
Recover time: 1997-04-17 19:04:26
Data records: 1192 Deleted blocks: 0
Datafile parts: 1192 Deleted data: 0
Datafile pointer (bytes): 3 Keyfile pointer (bytes): 1
Max datafile length: 16777215 Max keyfile length: 131071
Recordlength: 834
Record format: Compressed
table description:
Key Start Len Index Type Root Blocksize Rec/key
1 2 4 unique unsigned long 10240 1024 1
2 32 30 multip. text 54272 1024 1
Field Start Length Type Huff tree Bits
1 1 1 constant 1 0
2 2 4 zerofill(1) 2 9
3 6 4 no zeros, zerofill(1) 2 9
4 10 1 3 9
5 11 20 table-lookup 4 0
6 31 1 3 9
7 32 30 no endspace, not_always 5 9
8 62 35 no endspace, not_always, no empty 6 9
9 97 35 no empty 7 9
10 132 35 no endspace, not_always, no empty 6 9
11 167 4 zerofill(1) 2 9
12 171 16 no endspace, not_always, no empty 5 9
13 187 35 no endspace, not_always, no empty 6 9
14 222 4 zerofill(1) 2 9
15 226 16 no endspace, not_always, no empty 5 9
16 242 20 no endspace, not_always 8 9
17 262 20 no endspace, no empty 8 9
18 282 20 no endspace, no empty 5 9
19 302 30 no endspace, no empty 6 9
20 332 4 always zero 2 9
21 336 4 always zero 2 9
22 340 1 3 9
23 341 8 table-lookup 9 0
24 349 8 table-lookup 10 0
25 357 8 always zero 2 9
26 365 2 2 9
27 367 2 no zeros, zerofill(1) 2 9
28 369 4 no zeros, zerofill(1) 2 9
29 373 4 table-lookup 11 0
30 377 1 3 9
31 378 2 no zeros, zerofill(1) 2 9
32 380 8 no zeros 2 9
33 388 4 always zero 2 9
34 392 4 table-lookup 12 0
35 396 4 no zeros, zerofill(1) 13 9
36 400 4 no zeros, zerofill(1) 2 9
37 404 1 2 9
38 405 4 no zeros 2 9
39 409 4 always zero 2 9
40 413 4 no zeros 2 9
41 417 4 always zero 2 9
42 421 4 no zeros 2 9
43 425 4 always zero 2 9
44 429 20 no empty 3 9
45 449 30 no empty 3 9
46 479 1 14 4
47 480 1 14 4
48 481 79 no endspace, no empty 15 9
49 560 79 no empty 2 9
50 639 79 no empty 2 9
51 718 79 no endspace 16 9
52 797 8 no empty 2 9
53 805 1 17 1
54 806 1 3 9
55 807 20 no empty 3 9
56 827 4 no zeros, zerofill(2) 2 9
57 831 4 no zeros, zerofill(1) 2 9
myisampack displays the following kinds of
information:
normal
The number of columns for which no extra packing is used.
empty-space
The number of columns containing values that are only
spaces. These occupy one bit.
empty-zero
The number of columns containing values that are only
binary zeros. These occupy one bit.
empty-fill
The number of integer columns that do not occupy the full
byte range of their type. These are changed to a smaller
type. For example, a BIGINT column
(eight bytes) can be stored as a
TINYINT column (one byte) if all its
values are in the range from -128 to
127.
pre-space
The number of decimal columns that are stored with leading
spaces. In this case, each value contains a count for the
number of leading spaces.
end-space
The number of columns that have a lot of trailing spaces.
In this case, each value contains a count for the number
of trailing spaces.
table-lookup
The column had only a small number of different values,
which were converted to an ENUM before
Huffman compression.
zero
The number of columns for which all values are zero.
Original trees
The initial number of Huffman trees.
After join
The number of distinct Huffman trees left after joining
trees to save some header space.
After a table has been compressed, myisamchk
-dvv prints additional information about each
column:
Type
The data type. The value may contain any of the following
descriptors:
constant
All rows have the same value.
no endspace
Do not store endspace.
no endspace, not_always
Do not store endspace and do not do endspace
compression for all values.
no endspace, no empty
Do not store endspace. Do not store empty values.
table-lookup
The column was converted to an
ENUM.
zerofill(N)
The most significant N
bytes in the value are always 0 and are not stored.
no zeros
Do not store zeros.
always zero
Zero values are stored using one bit.
Huff tree
The number of the Huffman tree associated with the column.
Bits
The number of bits used in the Huffman tree.
After you run myisampack, you must run
myisamchk to re-create any indexes. At this
time, you can also sort the index blocks and create statistics
needed for the MySQL optimizer to work more efficiently:
shell> myisamchk -rq --sort-index --analyze tbl_name.MYI
After you have installed the packed table into the MySQL
database directory, you should execute mysqladmin
flush-tables to force mysqld to
start using the new table.
To unpack a packed table, use the --unpack
option to myisamchk.
8.5. mysql — The MySQL Command-Line Tool
mysql is a simple SQL shell (with GNU
readline capabilities). It supports
interactive and non-interactive use. When used interactively,
query results are presented in an ASCII-table format. When
used non-interactively (for example, as a filter), the result
is presented in tab-separated format. The output format can be
changed using command options.
If you have problems due to insufficient memory for large
result sets, use the --quick option. This
forces mysql to retrieve results from the
server a row at a time rather than retrieving the entire
result set and buffering it in memory before displaying it.
This is done by returning the result set using the
mysql_use_result() C API function in the
client/server library rather than
mysql_store_result().
Using mysql is very easy. Invoke it from
the prompt of your command interpreter as follows:
shell> mysql db_name
Or:
shell> mysql --user=user_name --password=your_password db_name
Then type an SQL statement, end it with
‘;’, \g, or
\G and press Enter.
You can execute SQL statements in a script file (batch file)
like this:
shell> mysql db_name < script.sql > output.tab
mysql supports the following options:
--help, -?
Display a help message and exit.
--auto-rehash
Enable automatic rehashing. This option is on by default,
which enables table and column name completion. Use
--skip-auto-rehash to disable rehashing.
That causes mysql to start faster, but
you must issue the rehash command if
you want to use table and column name completion.
--batch, -B
Print results using tab as the column separator, with each
row on a new line. With this option,
mysql does not use the history file.
--character-sets-dir=path
The directory where character sets are installed. See
Section 5.11.1, “The Character Set Used for Data and Sorting”.
--column-names
Write column names in results.
--compress, -C
Compress all information sent between the client and the
server if both support compression.
--database=db_name,
-D db_name
The database to use. This is useful primarily in an option
file.
--debug[=debug_options],
-#
[debug_options]
Write a debugging log. The
debug_options string often is
'd:t:o,file_name'.
The default is
'd:t:o,/tmp/mysql.trace'.
--debug-info, -T
Print some debugging information when the program exits.
--default-character-set=charset_name
Use charset_name as the default
character set. See Section 5.11.1, “The Character Set Used for Data and Sorting”.
--delimiter=str
Set the statement delimiter. The default is the semicolon
character (‘;’).
--execute=statement,
-e statement
Execute the statement and quit. The default output format
is like that produced with --batch. See
Section 4.3.1, “Using Options on the Command Line”, for some examples.
--force, -f
Continue even if an SQL error occurs.
--host=host_name,
-h host_name
Connect to the MySQL server on the given host.
--html, -H
Produce HTML output.
--ignore-spaces, -i
Ignore spaces after function names. The effect of this is
described in the discussion for the
IGNORE_SPACE SQL mode (see
Section 5.2.5, “The Server SQL Mode”).
--line-numbers
Write line numbers for errors. Disable this with
--skip-line-numbers.
--local-infile[={0|1}]
Enable or disable LOCAL capability for
LOAD DATA INFILE. With no value, the
option enables LOCAL. The option may be
given as --local-infile=0 or
--local-infile=1 to explicitly disable or
enable LOCAL. Enabling
LOCAL has no effect if the server does
not also support it.
--named-commands, -G
Enable named mysql commands.
Long-format commands are allowed, not just short-format
commands. For example, quit and
\q both are recognized. Use
--skip-named-commands to disable named
commands. See Section 8.5.2, “mysql Commands”.
--no-auto-rehash, -A
Deprecated form of -skip-auto-rehash. See
the description for --auto-rehash.
--no-beep, -b
Do not beep when errors occur.
--no-named-commands, -g
Disable named commands. Use the \* form
only, or use named commands only at the beginning of a
line ending with a semicolon
(‘;’).
mysql starts with this option
enabled by default. However, even
with this option, long-format commands still work from the
first line. See Section 8.5.2, “mysql Commands”.
--no-pager
Deprecated form of --skip-pager. See the
--pager option.
--no-tee
Do not copy output to a file.
Section 8.5.2, “mysql Commands”, discusses tee files
further.
--one-database, -o
Ignore statements except those for the default database
named on the command line. This is useful for skipping
updates to other databases in the binary log.
--pager[=command]
Use the given command for paging query output. If the
command is omitted, the default pager is the value of your
PAGER environment variable. Valid
pagers are less,
more, cat [>
filename], and so forth. This option works only
on Unix. It does not work in batch mode. To disable
paging, use --skip-pager.
Section 8.5.2, “mysql Commands”, discusses output paging
further.
--password[=password],
-p[password]
The password to use when connecting to the server. If you
use the short option form (-p), you
cannot have a space between the
option and the password. If you omit the
password value following the
--password or -p option
on the command line, you are prompted for one.
Specifying a password on the command line should be
considered insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
--port=port_num,
-P port_num
The TCP/IP port number to use for the connection.
--prompt=format_str
Set the prompt to the specified format. The default is
mysql>. The special sequences that
the prompt can contain are described in
Section 8.5.2, “mysql Commands”.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use.
--quick, -q
Do not cache each query result, print each row as it is
received. This may slow down the server if the output is
suspended. With this option, mysql does
not use the history file.
--raw, -r
Write column values without escape conversion. Often used
with the --batch option.
--reconnect
If the connection to the server is lost, automatically try
to reconnect. A single reconnect attempt is made each time
the connection is lost. To suppress reconnection behavior,
use --skip-reconnect.
--safe-updates,
--i-am-a-dummy, -U
Allow only those UPDATE and
DELETE statements that specify which
rows to modify by using key values. If you have set this
option in an option file, you can override it by using
--safe-updates on the command line. See
Section 8.5.4, “mysql Tips”, for more information about
this option.
--secure-auth
Do not send passwords to the server in old (pre-4.1.1)
format. This prevents connections except for servers that
use the newer password format.
--show-warnings
Cause warnings to be shown after each statement if there
are any. This option applies to interactive and batch
mode. This option was added in MySQL 5.0.6.
--sigint-ignore
Ignore SIGINT signals (typically the
result of typing Control-C).
--silent, -s
Silent mode. Produce less output. This option can be given
multiple times to produce less and less output.
--skip-column-names, -N
Do not write column names in results.
--skip-line-numbers, -L
Do not write line numbers for errors. Useful when you want
to compare result files that include error messages.
--socket=path,
-S path
For connections to localhost, the Unix
socket file to use, or, on Windows, the name of the named
pipe to use.
--table, -t
Display output in table format. This is the default for
interactive use, but can be used to produce table output
in batch mode.
--tee=file_name
Append a copy of output to the given file. This option
does not work in batch mode. in
Section 8.5.2, “mysql Commands”, discusses tee files
further.
--unbuffered, -n
Flush the buffer after each query.
--user=user_name,
-u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Produce more output about what the program
does. This option can be given multiple times to produce
more and more output. (For example, -v -v
-v produces table output format even in batch
mode.)
--version, -V
Display version information and exit.
--vertical, -E
Print query output rows vertically (one line per coluumn
value). Without this option, you can specify vertical
output for individual statements by terminating them with
\G.
--wait, -w
If the connection cannot be established, wait and retry
instead of aborting.
--xml, -X
Produce XML output.
You can also set the following variables by using
--var_name=value
syntax:
connect_timeout
The number of seconds before connection timeout. (Default
value is 0.)
max_allowed_packet
The maximum packet length to send to or receive from the
server. (Default value is 16MB.)
max_join_size
The automatic limit for rows in a join when using
--safe-updates. (Default value is
1,000,000.)
net_buffer_length
The buffer size for TCP/IP and socket communication.
(Default value is 16KB.)
select_limit
The automatic limit for SELECT
statements when using --safe-updates.
(Default value is 1,000.)
It is also possible to set variables by using
--set-variable=var_name=value
or -O
var_name=value
syntax. This syntax is deprecated.
On Unix, the mysql client writes a record
of executed statements to a history file. By default, the
history file is named .mysql_history and
is created in your home directory. To specify a different
file, set the value of the MYSQL_HISTFILE
environment variable.
If you do not want to maintain a history file, first remove
.mysql_history if it exists, and then use
either of the following techniques:
Set the MYSQL_HISTFILE variable to
/dev/null. To cause this setting to
take effect each time you log in, put the setting in one
of your shell's startup files.
Create .mysql_history as a symbolic
link to /dev/null:
shell> ln -s /dev/null $HOME/.mysql_history
You need do this only once.
mysql sends each SQL statement that you
issue to the server to be executed. There is also a set of
commands that mysql itself interprets. For
a list of these commands, type help or
\h at the mysql>
prompt:
mysql> help
List of all MySQL commands:
Note that all text commands must be first on line and end with ';'
? (\?) Synonym for `help'.
clear (\c) Clear command.
connect (\r) Reconnect to the server. Optional arguments are db and host.
delimiter (\d) Set statement delimiter. NOTE: Takes the rest of the line as
new delimiter.
edit (\e) Edit command with $EDITOR.
ego (\G) Send command to mysql server, display result vertically.
exit (\q) Exit mysql. Same as quit.
go (\g) Send command to mysql server.
help (\h) Display this help.
nopager (\n) Disable pager, print to stdout.
notee (\t) Don't write into outfile.
pager (\P) Set PAGER [to_pager]. Print the query results via PAGER.
print (\p) Print current command.
prompt (\R) Change your mysql prompt.
quit (\q) Quit mysql.
rehash (\#) Rebuild completion hash.
source (\.) Execute an SQL script file. Takes a file name as an argument.
status (\s) Get status information from the server.
system (\!) Execute a system shell command.
tee (\T) Set outfile [to_outfile]. Append everything into given
outfile.
use (\u) Use another database. Takes database name as argument.
charset (\C) Switch to another charset. Might be needed for processing binlog with multi-byte charsets.
warnings (\W) Show warnings after every statement.
nowarning (\w) Don't show warnings after every statement.
Each command has both a long and short form. The long form is
not case sensitive; the short form is. The long form can be
followed by an optional semicolon terminator, but the short
form should not.
In the delimiter command, you should avoid
the use of the backslash (‘\’)
character because that is the escape character for MySQL.
The edit, nopager,
pager, and system
commands work only in Unix.
The status command provides some
information about the connection and the server you are using.
If you are running in --safe-updates mode,
status also prints the values for the
mysql variables that affect your queries.
To log queries and their output, use the
tee command. All the data displayed on the
screen is appended into a given file. This can be very useful
for debugging purposes also. You can enable this feature on
the command line with the --tee option, or
interactively with the tee command. The
tee file can be disabled interactively with
the notee command. Executing
tee again re-enables logging. Without a
parameter, the previous file is used. Note that
tee flushes query results to the file after
each statement, just before mysql prints
its next prompt.
By using the --pager option, it is possible
to browse or search query results in interactive mode with
Unix programs such as less,
more, or any other similar program. If you
specify no value for the option, mysql
checks the value of the PAGER environment
variable and sets the pager to that. Output paging can be
enabled interactively with the pager
command and disabled with nopager. The
command takes an optional argument; if given, the paging
program is set to that. With no argument, the pager is set to
the pager that was set on the command line, or
stdout if no pager was specified.
Output paging works only in Unix because it uses the
popen() function, which does not exist on
Windows. For Windows, the tee option can be
used instead to save query output, although this is not as
convenient as pager for browsing output in
some situations.
Here are a few tips about the pager
command:
You can use it to write to a file and the results go only
to the file:
mysql> pager cat > /tmp/log.txt
You can also pass any options for the program that you
want to use as your pager:
mysql> pager less -n -i -S
In the preceding example, note the -S
option. You may find it very useful for browsing wide
query results. Sometimes a very wide result set is
difficult to read on the screen. The -S
option to less can make the result set
much more readable because you can scroll it horizontally
using the left-arrow and right-arrow keys. You can also
use -S interactively within
less to switch the horizontal-browse
mode on and off. For more information, read the
less manual page:
shell> man less
You can specify very complex pager commands for handling
query output:
mysql> pager cat | tee /dr1/tmp/res.txt \
| tee /dr2/tmp/res2.txt | less -n -i -S
In this example, the command would send query results to
two files in two different directories on two different
filesystems mounted on /dr1 and
/dr2, yet still display the results
onscreen via less.
You can also combine the tee and
pager functions. Have a
tee file enabled and
pager set to less, and
you are able to browse the results using the
less program and still have everything
appended into a file the same time. The difference between the
Unix tee used with the
pager command and the
mysql built-in tee
command is that the built-in tee works even
if you do not have the Unix tee available.
The built-in tee also logs everything that
is printed on the screen, whereas the Unix
tee used with pager does
not log quite that much. Additionally, tee
file logging can be turned on and off interactively from
within mysql. This is useful when you want
to log some queries to a file, but not others.
The default mysql> prompt can be
reconfigured. The string for defining the prompt can contain
the following special sequences:
‘\’ followed by any other
letter just becomes that letter.
If you specify the prompt command with no
argument, mysql resets the prompt to the
default of mysql>.
You can set the prompt in several ways:
Use an environment variable. You can
set the MYSQL_PS1 environment variable
to a prompt string. For example:
shell> export MYSQL_PS1="(\u@\h) [\d]> "
Use a command-line option. You can
set the --prompt option on the command
line to mysql. For example:
shell> mysql --prompt="(\u@\h) [\d]> "
(user@host) [database]>
Use an option file. You can set the
prompt option in the
[mysql] group of any MySQL option file,
such as /etc/my.cnf or the
.my.cnf file in your home directory.
For example:
[mysql]
prompt=(\\u@\\h) [\\d]>\\_
In this example, note that the backslashes are doubled. If
you set the prompt using the prompt
option in an option file, it is advisable to double the
backslashes when using the special prompt options. There
is some overlap in the set of allowable prompt options and
the set of special escape sequences that are recognized in
option files. (These sequences are listed in
Section 4.3.2, “Using Option Files”.) The overlap may cause you
problems if you use single backslashes. For example,
\s is interpreted as a space rather
than as the current seconds value. The following example
shows how to define a prompt within an option file to
include the current time in
HH:MM:SS> format:
[mysql]
prompt="\\r:\\m:\\s> "
Set the prompt interactively. You can
change your prompt interactively by using the
prompt (or \R)
command. For example:
mysql> prompt (\u@\h) [\d]>\_
PROMPT set to '(\u@\h) [\d]>\_'
(user@host) [database]>
(user@host) [database]> prompt
Returning to default PROMPT of mysql>
mysql>
8.5.3. Executing SQL Statements from a Text File
The mysql client typically is used
interactively, like this:
shell> mysql db_name
However, it is also possible to put your SQL statements in a
file and then tell mysql to read its input
from that file. To do so, create a text file
text_file that contains the
statements you wish to execute. Then invoke
mysql as shown here:
shell> mysql db_name < text_file
If you place a USE
db_name statement as the
first statement in the file, it is unnecessary to specify the
database name on the command line:
shell> mysql < text_file
If you are already running mysql, you can
execute an SQL script file using the source
or \. command:
mysql> source file_name
mysql> \. file_name
Sometimes you may want your script to display progress
information to the user. For this you can insert statements
like this:
SELECT '<info_to_display>' AS ' ';
The statement shown outputs
<info_to_display>.
For more information about batch mode, see
Section 3.5, “Using mysql in Batch Mode”.
This section describes some techniques that can help you use
mysql more effectively.
8.5.4.1. Displaying Query Results Vertically
Some query results are much more readable when displayed
vertically, instead of in the usual horizontal table format.
Queries can be displayed vertically by terminating the query
with \G instead of a semicolon. For example, longer text
values that include newlines often are much easier to read
with vertical output:
mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G
*************************** 1. row ***************************
msg_nro: 3068
date: 2000-03-01 23:29:50
time_zone: +0200
mail_from: Monty
reply: monty@no.spam.com
mail_to: "Thimble Smith" <tim@no.spam.com>
sbj: UTF-8
txt: >>>>> "Thimble" == Thimble Smith writes:
Thimble> Hi. I think this is a good idea. Is anyone familiar
Thimble> with UTF-8 or Unicode? Otherwise, I'll put this on my
Thimble> TODO list and see what happens.
Yes, please do that.
Regards,
Monty
file: inbox-jani-1
hash: 190402944
1 row in set (0.09 sec)
8.5.4.2. Using the --safe-updates Option
For beginners, a useful startup option is
--safe-updates (or
--i-am-a-dummy, which has the same effect).
It is helpful for cases when you might have issued a
DELETE FROM
tbl_name statement but
forgotten the WHERE clause. Normally,
such a statement deletes all rows from the table. With
--safe-updates, you can delete rows only by
specifying the key values that identify them. This helps
prevent accidents.
When you use the --safe-updates option,
mysql issues the following statement when
it connects to the MySQL server:
SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=1000, SQL_MAX_JOIN_SIZE=1000000;
See Section 13.5.3, “SET Syntax”.
The SET statement has the following
effects:
You are not allowed to execute an
UPDATE or DELETE
statement unless you specify a key constraint in the
WHERE clause or provide a
LIMIT clause (or both). For example:
UPDATE tbl_name SET not_key_column=val WHERE key_column=val;
UPDATE tbl_name SET not_key_column=val LIMIT 1;
The server limits all large SELECT
results to 1,000 rows unless the statement includes a
LIMIT clause.
The server aborts multiple-table
SELECT statements that probably need
to examine more than 1,000,000 row combinations.
To specify limits different from 1,000 and 1,000,000, you
can override the defaults by using the
--select_limit and
--max_join_size options:
shell> mysql --safe-updates --select_limit=500 --max_join_size=10000
8.5.4.3. Disabling mysql Auto-Reconnect
If the mysql client loses its connection
to the server while sending a query, it immediately and
automatically tries to reconnect once to the server and send
the query again. However, even if mysql
succeeds in reconnecting, your first connection has ended
and all your previous session objects and settings are lost:
temporary tables, the autocommit mode, and user-defined and
session variables. Also, any current transaction rolls back.
This behavior may be dangerous for you, as in the following
example where the server was shut down and restarted without
you knowing it:
mysql> SET @a=1;
Query OK, 0 rows affected (0.05 sec)
mysql> INSERT INTO t VALUES(@a);
ERROR 2006: MySQL server has gone away
No connection. Trying to reconnect...
Connection id: 1
Current database: test
Query OK, 1 row affected (1.30 sec)
mysql> SELECT * FROM t;
+------+
| a |
+------+
| NULL |
+------+
1 row in set (0.05 sec)
The @a user variable has been lost with
the connection, and after the reconnection it is undefined.
If it is important to have mysql
terminate with an error if the connection has been lost, you
can start the mysql client with the
--skip-reconnect option.
8.6. mysqlaccess — Client for Checking Access Privileges
mysqlaccess is a diagnostic tool that Yves
Carlier has provided for the MySQL distribution. It checks the
access privileges for a hostname, username, and database
combination. Note that mysqlaccess checks
access using only the user,
db, and host tables. It
does not check table, column, or routine privileges specified
in the tables_priv,
columns_priv, or
procs_priv tables.
Invoke mysqlaccess like this:
shell> mysqlaccess [host_name [user_name [db_name]]] [options]
mysqlaccess understands the following
options:
--help, -?
Display a help message and exit.
--brief, -b
Generate reports in single-line tabular format.
--commit
Copy the new access privileges from the temporary tables
to the original grant tables. The grant tables must be
flushed for the new privileges to take effect. (For
example, execute a mysqladmin reload
command.)
--copy
Reload the temporary grant tables from original ones.
--db=db_name,
-d db_name
Specify the database name.
--debug=N
Specify the debug level. N can
be an integer from 0 to 3.
--host=host_name,
-h host_name
The hostname to use in the access privileges.
--howto
Display some examples that show how to use
mysqlaccess.
--old_server
Assume that the server is an old MySQL server (before
MySQL 3.21) that does not yet know how to handle full
WHERE clauses.
--password[=password],
-p[password]
The password to use when connecting to the server. If you
omit the password value
following the --password or
-p option on the command line, you are
prompted for one.
Specifying a password on the command line should be
considered insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
--plan
Display suggestions and ideas for future releases.
--preview
Show the privilege differences after making changes to the
temporary grant tables.
--relnotes
Display the release notes.
--rhost=host_name,
-H host_name
Connect to the MySQL server on the given host.
--rollback
Undo the most recent changes to the temporary grant
tables.
--spassword[=password],
-P[password]
The password to use when connecting to the server as the
superuser. If you omit the
password value following the
--password or -p option
on the command line, you are prompted for one.
Specifying a password on the command line should be
considered insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
--superuser=user_name,
-U user_name
Specify the username for connecting as the superuser.
--table, -t
Generate reports in table format.
--user=user_name,
-u user_name
The username to use in the access privileges.
--version, -v
Display version information and exit.
If your MySQL distribution is installed in some non-standard
location, you must change the location where
mysqlaccess expects to find the
mysql client. Edit the
mysqlaccess script at approximately line
18. Search for a line that looks like this:
$MYSQL = '/usr/local/bin/mysql'; # path to mysql executable
Change the path to reflect the location where
mysql actually is stored on your system. If
you do not do this, a Broken pipe error
will occur when you run mysqlaccess.
8.7. mysqladmin — Client for Administering a MySQL Server
mysqladmin is a client for performing
administrative operations. You can use it to check the
server's configuration and current status, to create and drop
databases, and more.
Invoke mysqladmin like this:
shell> mysqladmin [options] command [command-arg] [command [command-arg]] ...
mysqladmin supports the commands described
in the following list. Some of the commands take an argument
following the command name.
create
db_name
Create a new database named
db_name.
debug
Tell the server to write debug information to the error
log.
drop db_name
Delete the database named
db_name and all its tables.
extended-status
Display the server status variables and their values.
flush-hosts
Flush all information in the host cache.
flush-logs
Flush all logs.
flush-privileges
Reload the grant tables (same as
reload).
flush-status
Clear status variables.
flush-tables
Flush all tables.
flush-threads
Flush the thread cache.
kill
id,id,...
Kill server threads. If multiple thread ID values are
given, there must be no spaces in the list.
old-password
new-password
This is like the password command but
stores the password using the old (pre-4.1)
password-hashing format. (See
Section 5.8.9, “Password Hashing as of MySQL 4.1”.)
password
new-password
Set a new password. This changes the password to
new-password for the account
that you use with mysqladmin for
connecting to the server. Thus, the next time you invoke
mysqladmin (or any other client
program) using the same account, you will need to specify
the new password.
If the new-password value
contains spaces or other characters that are special to
your command interpreter, you need to enclose it within
quotes. On Windows, be sure to use double quotes rather
than single quotes; single quotes are not stripped from
the password, but rather are interpreted as part of the
password. For example:
shell> mysqladmin password "my new password"
ping
Check whether the server is alive. The return status from
mysqladmin is 0 if the server is
running, 1 if it is not. This is 0 even in case of an
error such as Access denied, because
this means that the server is running but refused the
connection, which is different from the server not
running.
processlist
Show a list of active server threads. This is like the
output of the SHOW PROCESSLIST
statement. If the --verbose option is
given, the output is like that of SHOW FULL
PROCESSLIST. (See
Section 13.5.4.19, “SHOW PROCESSLIST Syntax”.)
reload
Reload the grant tables.
refresh
Flush all tables and close and open log files.
shutdown
Stop the server.
start-slave
Start replication on a slave server.
status
Display a short server status message.
stop-slave
Stop replication on a slave server.
variables
Display the server system variables and their values.
version
Display version information from the server.
All commands can be shortened to any unique prefix. For
example:
shell> mysqladmin proc stat
+----+-------+-----------+----+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+-------+-----------+----+---------+------+-------+------------------+
| 51 | monty | localhost | | Query | 0 | | show processlist |
+----+-------+-----------+----+---------+------+-------+------------------+
Uptime: 1473624 Threads: 1 Questions: 39487
Slow queries: 0 Opens: 541 Flush tables: 1
Open tables: 19 Queries per second avg: 0.0268
The mysqladmin status command result
displays the following values:
Uptime
The number of seconds the MySQL server has been running.
Threads
The number of active threads (clients).
Questions
The number of questions (queries) from clients since the
server was started.
Slow queries
The number of queries that have taken more than
long_query_time seconds. See
Section 5.12.4, “The Slow Query Log”.
Opens
The number of tables the server has opened.
Flush tables
The number of flush-*,
refresh, and reload
commands the server has executed.
Open tables
The number of tables that currently are open.
Memory in use
The amount of memory allocated directly by
mysqld. This value is displayed only
when MySQL has been compiled with
--with-debug=full.
Maximum memory used
The maximum amount of memory allocated directly by
mysqld. This value is displayed only
when MySQL has been compiled with
--with-debug=full.
If you execute mysqladmin shutdown when
connecting to a local server using a Unix socket file,
mysqladmin waits until the server's process
ID file has been removed, to ensure that the server has
stopped properly.
mysqladmin supports the following options:
--help, -?
Display a help message and exit.
--character-sets-dir=path
The directory where character sets are installed. See
Section 5.11.1, “The Character Set Used for Data and Sorting”.
--compress, -C
Compress all information sent between the client and the
server if both support compression.
--count=N,
-c N
The number of iterations to make for repeated command
execution. This works only with the
--sleep option.
--debug[=debug_options],
-#
[debug_options]
Write a debugging log. The
debug_options string often is
'd:t:o,file_name'.
The default is
'd:t:o,/tmp/mysqladmin.trace'.
--default-character-set=charset_name
Use charset_name as the default
character set. See Section 5.11.1, “The Character Set Used for Data and Sorting”.
--force, -f
Do not ask for confirmation for the drop
db_name command. With
multiple commands, continue even if an error occurs.
--host=host_name,
-h host_name
Connect to the MySQL server on the given host.
--password[=password],
-p[password]
The password to use when connecting to the server. If you
use the short option form (-p), you
cannot have a space between the
option and the password. If you omit the
password value following the
--password or -p option
on the command line, you are prompted for one.
Specifying a password on the command line should be
considered insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
--port=port_num,
-P port_num
The TCP/IP port number to use for the connection.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use.
--relative, -r
Show the difference between the current and previous
values when used with the --sleep option.
Currently, this option works only with the
extended-status command.
--silent, -s
Exit silently if a connection to the server cannot be
established.
--sleep=delay,
-i delay
Execute commands repeatedly, sleeping for
delay seconds in between. The
--count option determines the number of
iterations.
--socket=path,
-S path
For connections to localhost, the Unix
socket file to use, or, on Windows, the name of the named
pipe to use.
--user=user_name,
-u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Print more information about what the
program does.
--version, -V
Display version information and exit.
--vertical, -E
Print output vertically. This is similar to
--relative, but prints output vertically.
--wait[=count],
-w[count]
If the connection cannot be established, wait and retry
instead of aborting. If a count
value is given, it indicates the number of times to retry.
The default is one time.
You can also set the following variables by using
--var_name=value
syntax:
It is also possible to set variables by using
--set-variable=var_name=value
or -O
var_name=value
syntax. This syntax is deprecated.
8.8. mysqlbinlog — Utility for Processing Binary Log Files
The binary log files that the server generates are written in
binary format. To examine these files in text format, use the
mysqlbinlog utility.
Invoke mysqlbinlog like this:
shell> mysqlbinlog [options] log_file ...
For example, to display the contents of the binary log file
named binlog.000003, use this command:
shell> mysqlbinlog binlog.0000003
The output includes all events contained in
binlog.000003. Event information includes
the statement executed, the time the statement took, the
thread ID of the client that issued it, the timestamp when it
was executed, and so forth.
The output from mysqlbinlog can be
re-executed (for example, by using it as input to
mysql) to reapply the statements in the
log. This is useful for recovery operations after a server
crash. For other usage examples, see the discussion later in
this section.
Normally, you use mysqlbinlog to read
binary log files directly and apply them to the local MySQL
server. It is also possible to read binary logs from a remote
server by using the --read-from-remote-server
option. When you read remote binary logs, the connection
parameter options can be given to indicate how to connect to
the server. These options are --host,
--password, --port,
--protocol, --socket, and
--user; they are ignored except when you also
use the --read-from-remote-server option.
You can also use mysqlbinlog to read relay
log files written by a slave server in a replication setup.
Relay logs have the same format as binary log files.
Binary logs and relay logs are discussed further in
Section 5.12.3, “The Binary Log”, and
Section 6.3.4, “Replication Relay and Status Files”. further.
mysqlbinlog supports the following options:
--help, -?
Display a help message and exit.
--character-sets-dir=path
The directory where character sets are installed. See
Section 5.11.1, “The Character Set Used for Data and Sorting”.
--database=db_name,
-d db_name
List entries for just this database (local log only).
--debug[=debug_options],
-#
[debug_options]
Write a debugging log. A typical
debug_options string is often
'd:t:o,file_name'.
--disable-log-bin, -D
Disable binary logging. This is useful for avoiding an
endless loop if you use the --to-last-log
option and are sending the output to the same MySQL
server. This option also is useful when restoring after a
crash to avoid duplication of the statements you have
logged.
This option requires that you have the
SUPER privilege. It causes
mysqlbinlog to include a SET
SQL_LOG_BIN=0 statement in its output to disable
binary logging of the remaining output. The
SET statement is ineffective unless you
have the SUPER privilege.
--force-read, -f
With this option, if mysqlbinlog reads
a binary log event that it does not recognize, it prints a
warning, ignores the event, and continues. Without this
option, mysqlbinlog stops if it reads
such an event.
--hexdump, -H
Display a hex dump of the log in comments. This output can
be helpful for replication debugging. Hex dump format is
discussed later in this section. This option was added in
MySQL 5.0.16.
--host=host_name,
-h host_name
Get the binary log from the MySQL server on the given
host.
--local-load=path,
-l path
Prepare local temporary files for LOAD DATA
INFILE in the specified directory.
--offset=N,
-o N
Skip the first N entries in the
log.
--password[=password],
-p[password]
The password to use when connecting to the server. If you
use the short option form (-p), you
cannot have a space between the
option and the password. If you omit the
password value following the
--password or -p option
on the command line, you are prompted for one.
Specifying a password on the command line should be
considered insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
--port=port_num,
-P port_num
The TCP/IP port number to use for connecting to a remote
server.
--position=N,
-j N
Deprecated. Use --start-position instead.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use.
--read-from-remote-server,
-R
Read the binary log from a MySQL server rather than
reading a local log file. Any connection parameter options
are ignored unless this option is given as well. These
options are --host,
--password, --port,
--protocol, --socket,
and --user.
--result-file=name,
-r name
Direct output to the given file.
--short-form, -s
Display only the statements contained in the log, without
any extra information.
--socket=path,
-S path
For connections to localhost, the Unix
socket file to use, or, on Windows, the name of the named
pipe to use.
--start-datetime=datetime
Start reading the binary log at the first event having a
timestamp equal to or later than the
datetime argument. The
datetime value is relative to
the local time zone on the machine where you run
mysqlbinlog. The value should be in a
format accepted for the DATETIME or
TIMESTAMP data types. For example:
shell> mysqlbinlog --start-datetime="2005-12-25 11:25:56" binlog.000003
This option is useful for point-in-time recovery. See
Section 5.10.2, “Example Backup and Recovery Strategy”.
--stop-datetime=datetime
Stop reading the binary log at the first event having a
timestamp equal or posterior to the
datetime argument. This option
is useful for point-in-time recovery. See the description
of the --start-datetime option for
information about the datetime
value.
--start-position=N
Start reading the binary log at the first event having a
position equal to the N
argument.
--stop-position=N
Stop reading the binary log at the first event having a
position equal or greater than the
N argument.
--to-last-log, -t
Do not stop at the end of the requested binary log from a
MySQL server, but rather continue printing until the end
of the last binary log. If you send the output to the same
MySQL server, this may lead to an endless loop. This
option requires
--read-from-remote-server.
--user=user_name,
-u user_name
The MySQL username to use when connecting to a remote
server.
--version, -V
Display version information and exit.
You can also set the following variable by using
--var_name=value
syntax:
It is also possible to set variables by using
--set-variable=var_name=value
or -O
var_name=value
syntax. This syntax is deprecated.
You can pipe the output of mysqlbinlog into
the mysql client to execute the statements
contained in the binary log. This is used to recover from a
crash when you have an old backup (see
Section 5.10.1, “Database Backups”). For example:
shell> mysqlbinlog binlog.000001 | mysql
Or:
shell> mysqlbinlog binlog.[0-9]* | mysql
You can also redirect the output of
mysqlbinlog to a text file instead, if you
need to modify the statement log first (for example, to remove
statements that you do not want to execute for some reason).
After editing the file, execute the statements that it
contains by using it as input to the mysql
program.
mysqlbinlog has the
--start-position option, which prints only
those statements with an offset in the binary log greater than
or equal to a given position (the given position must match
the start of one event). It also has options to stop and start
when it sees an event with a given date and time. This enables
you to perform point-in-time recovery using the
--stop-datetime option (to be able to say,
for example, “roll forward my databases to how they were
today at 10:30 a.m.”).
If you have more than one binary log to execute on the MySQL
server, the safe method is to process them all using a single
connection to the server. Here is an example that demonstrates
what may be unsafe:
shell> mysqlbinlog binlog.000001 | mysql # DANGER!!
shell> mysqlbinlog binlog.000002 | mysql # DANGER!!
Processing binary logs this way using different connections to
the server causes problems if the first log file contains a
CREATE TEMPORARY TABLE statement and the
second log contains a statement that uses the temporary table.
When the first mysql process terminates,
the server drops the temporary table. When the second
mysql process attempts to use the table,
the server reports “unknown table.”
To avoid problems like this, use a single
connection to execute the contents of all binary logs that you
want to process. Here is one way to do so:
shell> mysqlbinlog binlog.000001 binlog.000002 | mysql
Another approach is to write all the logs to a single file and
then process the file:
shell> mysqlbinlog binlog.000001 > /tmp/statements.sql
shell> mysqlbinlog binlog.000002 >> /tmp/statements.sql
shell> mysql -e "source /tmp/statements.sql"
mysqlbinlog can produce output that
reproduces a LOAD DATA INFILE operation
without the original data file. mysqlbinlog
copies the data to a temporary file and writes a LOAD
DATA LOCAL INFILE statement that refers to the file.
The default location of the directory where these files are
written is system-specific. To specify a directory explicitly,
use the --local-load option.
Because mysqlbinlog converts LOAD
DATA INFILE statements to LOAD DATA LOCAL
INFILE statements (that is, it adds
LOCAL), both the client and the server that
you use to process the statements must be configured to allow
LOCAL capability. See
Section 5.7.4, “Security Issues with LOAD DATA LOCAL”.
Warning: The temporary files
created for LOAD DATA LOCAL statements are
not automatically deleted because they
are needed until you actually execute those statements. You
should delete the temporary files yourself after you no longer
need the statement log. The files can be found in the
temporary file directory and have names like
original_file_name-#-#.
The --hexdump option produces a hex dump of
the log contents in comments:
shell> mysqlbinlog --hexdump master-bin.000001
With the preceding command, the output might look like this:
/*!40019 SET @@session.max_insert_delayed_threads=0*/;
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
# at 4
#051024 17:24:13 server id 1 end_log_pos 98
# Position Timestamp Type Master ID Size Master Pos Flags
# 00000004 9d fc 5c 43 0f 01 00 00 00 5e 00 00 00 62 00 00 00 00 00
# 00000017 04 00 35 2e 30 2e 31 35 2d 64 65 62 75 67 2d 6c |..5.0.15.debug.l|
# 00000027 6f 67 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |og..............|
# 00000037 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
# 00000047 00 00 00 00 9d fc 5c 43 13 38 0d 00 08 00 12 00 |.......C.8......|
# 00000057 04 04 04 04 12 00 00 4b 00 04 1a |.......K...|
# Start: binlog v 4, server v 5.0.15-debug-log created 051024 17:24:13
# at startup
ROLLBACK;
Hex dump output currently contains the following elements.
This format might change in the future.
Position: The byte position within the
log file.
Timestamp: The event timestamp. In the
example shown, '9d fc 5c 43' is the
representation of '051024 17:24:13' in
hexadecimal.
Type: The type of the log event. In the
example shown, '0f' means that the
example event is a
FORMAT_DESCRIPTION_EVENT. The following
table lists the possible types.
Master ID: The server id of the master
that created the event.
Size: The size in bytes of the event.
Master Pos: The position of the event
in the original master log file.
Flags: 16 flags. Currently, the
following flags are used. The others are reserved for the
future.
The other flags are reserved for future use.
8.9. mysqlcheck — A Table Maintenance and Repair Program
The mysqlcheck client checks, repairs,
optimizes, and analyzes tables.
mysqlcheck is similar in function to
myisamchk, but works differently. The main
operational difference is that mysqlcheck
must be used when the mysqld server is
running, whereas myisamchk should be used
when it is not. The benefit of using
mysqlcheck is that you do not have to stop
the server to check or repair your tables.
mysqlcheck uses the SQL statements
CHECK TABLE, REPAIR
TABLE, ANALYZE TABLE, and
OPTIMIZE TABLE in a convenient way for the
user. It determines which statements to use for the operation
you want to perform, and then sends the statements to the
server to be executed. For details about which storage engines
each statement works with, see the descriptions for those
statements in Chapter 13, SQL Statement Syntax.
The MyISAM storage engine supports all four
statements, so mysqlcheck can be used to
perform all four operations on MyISAM
tables. Other storage engines do not necessarily support all
operations. In such cases, an error message is displayed. For
example, if test.t is a
MEMORY table, an attempt to check it
produces this result:
shell> mysqlcheck test t
test.t
note : The storage engine for the table doesn't support check
There are three general ways to invoke
mysqlcheck:
shell> mysqlcheck [options] db_name [tables]
shell> mysqlcheck [options] --databases db_name1 [db_name2 db_name3...]
shell> mysqlcheck [options] --all-databases
If you do not name any tables following
db_name or if you use the
--databases or
--all-databases option, entire databases are
checked.
mysqlcheck has a special feature compared
to other client programs. The default behavior of checking
tables (--check) can be changed by renaming
the binary. If you want to have a tool that repairs tables by
default, you should just make a copy of
mysqlcheck named
mysqlrepair, or make a symbolic link to
mysqlcheck named
mysqlrepair. If you invoke
mysqlrepair, it repairs tables on command.
The following names can be used to change
mysqlcheck default behavior:
mysqlcheck supports the following options:
--help, -?
Display a help message and exit.
--all-databases, -A
Check all tables in all databases. This is the same as
using the --databases option and naming
all the databases on the command line.
--all-in-1, -1
Instead of issuing a statement for each table, execute a
single statement for each database that names all the
tables from that database to be processed.
--analyze, -a
Analyze the tables.
--auto-repair
If a checked table is corrupted, automatically fix it. Any
necessary repairs are done after all tables have been
checked.
--character-sets-dir=path
The directory where character sets are installed. See
Section 5.11.1, “The Character Set Used for Data and Sorting”.
--check, -c
Check the tables for errors. This is the default
operation.
--check-only-changed, -C
Check only tables that have changed since the last check
or that have not been closed properly.
--check-upgrade, -g
Invoke CHECK TABLE with the
FOR UPGRADE option to check tables for
incompatibilities with the current version of the server.
This option was added in MySQL 5.0.19.
--compress
Compress all information sent between the client and the
server if both support compression.
--databases, -B
Process all tables in the named databases. Normally,
mysqlcheck treats the first name
argument on the command line as a database name and
following names as table names. With this option, it
treats all name arguments as database names.
--debug[=debug_options],
-#
[debug_options]
Write a debugging log. A typical
debug_options string is often
'd:t:o,file_name'.
--default-character-set=charset_name
Use charset_name as the default
character set. See Section 5.11.1, “The Character Set Used for Data and Sorting”.
--extended, -e
If you are using this option to check tables, it ensures
that they are 100% consistent but takes a long time.
If you are using this option to repair tables, it runs an
extended repair that may not only take a long time to
execute, but may produce a lot of garbage rows also!
--fast, -F
Check only tables that have not been closed properly.
--force, -f
Continue even if an SQL error occurs.
--host=host_name,
-h host_name
Connect to the MySQL server on the given host.
--medium-check, -m
Do a check that is faster than an
--extended operation. This finds only
99.99% of all errors, which should be good enough in most
cases.
--optimize, -o
Optimize the tables.
--password[=password],
-p[password]
The password to use when connecting to the server. If you
use the short option form (-p), you
cannot have a space between the
option and the password. If you omit the
password value following the
--password or -p option
on the command line, you are prompted for one.
Specifying a password on the command line should be
considered insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
--port=port_num,
-P port_num
The TCP/IP port number to use for the connection.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use.
--quick, -q
If you are using this option to check tables, it prevents
the check from scanning the rows to check for incorrect
links. This is the fastest check method.
If you are using this option to repair tables, it tries to
repair only the index tree. This is the fastest repair
method.
--repair, -r
Perform a repair that can fix almost anything except
unique keys that are not unique.
--silent, -s
Silent mode. Print only error messages.
--socket=path,
-S path
For connections to localhost, the Unix
socket file to use, or, on Windows, the name of the named
pipe to use.
--tables
Overrides the --databases or
-B option. All name arguments following
the option are regarded as table names.
--use-frm
For repair operations on MyISAM tables,
get the table structure from the .frm
file so that the table can be repaired even if the
.MYI header is corrupted.
--user=user_name,
-u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Print information about the various stages
of program operation.
--version, -V
Display version information and exit.
8.10. mysqldump — A Database Backup Program
The mysqldump client is a backup program
originally written by Igor Romanenko. It can be used to dump a
database or a collection of databases for backup or for
transferring the data to another SQL server (not necessarily a
MySQL server). The dump contains SQL statements to create the
table or populate it, or both.
If you are doing a backup on the server, and your tables all
are MyISAM tables, consider using the
mysqlhotcopy instead because it can
accomplish faster backups and faster restores. See
Section 8.11, “mysqlhotcopy — A Database Backup Program”.
There are three general ways to invoke
mysqldump:
shell> mysqldump [options] db_name [tables]
shell> mysqldump [options] --databases db_name1 [db_name2 db_name3...]
shell> mysqldump [options] --all-databases
If you do not name any tables following
db_name or if you use the
--databases or
--all-databases option, entire databases are
dumped.
To get a list of the options your version of
mysqldump supports, execute
mysqldump --help.
If you run mysqldump without the
--quick or --opt option,
mysqldump loads the whole result set into
memory before dumping the result. This can be a problem if you
are dumping a big database. The --opt option
is enabled by default, but can be disabled with
--skip-opt.
If you are using a recent copy of the
mysqldump program to generate a dump to be
reloaded into a very old MySQL server, you should not use the
--opt or --extended-insert
option. Use --skip-opt instead.
mysqldump supports the following options:
--help, -?
Display a help message and exit.
--add-drop-database
Add a DROP DATABASE statement before
each CREATE DATABASE statement.
--add-drop-table
Add a DROP TABLE statement before each
CREATE TABLE statement.
--add-locks
Surround each table dump with LOCK
TABLES and UNLOCK TABLES
statements. This results in faster inserts when the dump
file is reloaded. See Section 7.2.16, “Speed of INSERT Statements”.
--all-databases, -A
Dump all tables in all databases. This is the same as
using the --databases option and naming
all the databases on the command line.
--allow-keywords
Allow creation of column names that are keywords. This
works by prefixing each column name with the table name.
--character-sets-dir=path
The directory where character sets are installed. See
Section 5.11.1, “The Character Set Used for Data and Sorting”.
--comments, -i
Write additional information in the dump file such as
program version, server version, and host. . This option
is enabled by default. To suppress additional, use
--skip-comments.
--compact
Produce less verbose output. This option suppresses
comments and enables the
--skip-add-drop-table,
--no-set-names,
--skip-disable-keys, and
--skip-add-locks options.
--compatible=name
Produce output that is more compatible with other database
systems or with older MySQL servers. The value of
name can be ansi,
mysql323, mysql40,
postgresql, oracle,
mssql, db2,
maxdb,
no_key_options,
no_table_options, or
no_field_options. To use several
values, separate them by commas. These values have the
same meaning as the corresponding options for setting the
server SQL mode. See Section 5.2.5, “The Server SQL Mode”.
This option does not guarantee compatibility with other
servers. It only enables those SQL mode values that are
currently available for making dump output more
compatible. For example,
--compatible=oracle does not map data
types to Oracle types or use Oracle comment syntax.
--complete-insert, -c
Use complete INSERT statements that
include column names.
--compress, -C
Compress all information sent between the client and the
server if both support compression.
--create-options
Include all MySQL-specific table options in the
CREATE TABLE statements.
--databases, -B
Dump several databases. Normally,
mysqldump treats the first name
argument on the command line as a database name and
following names as table names. With this option, it
treats all name arguments as database names.
CREATE DATABASE and
USE statements are included in the
output before each new database.
--debug[=debug_options],
-#
[debug_options]
Write a debugging log. The
debug_options string is often
'd:t:o,file_name'.
The default is
'd:t:o,/tmp/mysqldump.trace'.
--default-character-set=charset_name
Use charset_name as the default
character set. See Section 5.11.1, “The Character Set Used for Data and Sorting”. If
not specified, mysqldump uses
utf8.
--delayed-insert
Write INSERT DELAYED statements rather
than INSERT statements.
--delete-master-logs
On a master replication server, delete the binary logs
after performing the dump operation. This option
automatically enables --master-data.
--disable-keys, -K
For each table, surround the INSERT
statements with /*!40000 ALTER TABLE
tbl_name DISABLE KEYS
*/; and /*!40000 ALTER TABLE
tbl_name ENABLE KEYS
*/; statements. This makes loading the dump file
faster because the indexes are created after all rows are
inserted. This option is effective for
MyISAM tables only.
--extended-insert, -e
Use multiple-row INSERT syntax that
include several VALUES lists. This
results in a smaller dump file and speeds up inserts when
the file is reloaded.
--fields-terminated-by=...,
--fields-enclosed-by=...,
--fields-optionally-enclosed-by=...,
--fields-escaped-by=...,
--lines-terminated-by=...
These options are used with the -T option
and have the same meaning as the corresponding clauses for
LOAD DATA INFILE. See
Section 13.2.5, “LOAD DATA INFILE Syntax”.
--first-slave, -x
Deprecated. Now renamed to
--lock-all-tables.
--flush-logs, -F
Flush the MySQL server log files before starting the dump.
This option requires the RELOAD
privilege. Note that if you use this option in combination
with the --all-databases (or
-A) option, the logs are flushed
for each database dumped. The
exception is when using --lock-all-tables
or --master-data: In this case, the logs
are flushed only once, corresponding to the moment that
all tables are locked. If you want your dump and the log
flush to happen at exactly the same moment, you should use
--flush-logs together with either
--lock-all-tables or
--master-data.
--force, -f
Continue even if an SQL error occurs during a table dump.
--host=host_name,
-h host_name
Dump data from the MySQL server on the given host. The
default host is localhost.
--hex-blob
Dump binary columns using hexadecimal notation (for
example, 'abc' becomes
0x616263). The affected data types are
BINARY, VARBINARY,
and BLOB. As of MySQL 5.0.13,
BIT columns are affected as well.
--ignore-table=db_name.tbl_name
Do not dump the given table, which must be specified using
both the database and table names. To ignore multiple
tables, use this option multiple times.
--insert-ignore
Write INSERT statements with the
IGNORE option.
--lock-all-tables, -x
Lock all tables across all databases. This is achieved by
acquiring a global read lock for the duration of the whole
dump. This option automatically turns off
--single-transaction and
--lock-tables.
--lock-tables, -l
Lock all tables before starting the dump. The tables are
locked with READ LOCAL to allow
concurrent inserts in the case of
MyISAM tables. For transactional tables
such as InnoDB and
BDB,
--single-transaction is a much better
option, because it does not need to lock the tables at
all.
Please note that when dumping multiple databases,
--lock-tables locks tables for each
database separately. So, this option does not guarantee
that the tables in the dump file are logically consistent
between databases. Tables in different databases may be
dumped in completely different states.
--master-data[=value]
Write the binary log filename and position to the output.
This option requires the RELOAD
privilege and the binary log must be enabled. If the
option value is equal to 1, the position and filename are
written to the dump output in the form of a
CHANGE MASTER statement that makes a
slave server start from the correct position in the
master's binary logs if you use this SQL dump of the
master to set up a slave. If the option value is equal to
2, the CHANGE MASTER statement is
written as an SQL comment. This is the default action if
value is omitted.
The --master-data option turns on
--lock-all-tables, unless
--single-transaction also is specified
(in which case, a global read lock is only acquired a
short time at the beginning of the dump. See also the
description for --single-transaction. In
all cases, any action on logs happens at the exact moment
of the dump. This option automatically turns off
--lock-tables.
--no-autocommit
Enclose the INSERT statements for each
dumped table within SET AUTOCOMMIT=0
and COMMIT statements.
--no-create-db, -n
This option suppresses the CREATE
DATABASE statements that are otherwise included
in the output if the --databases or
--all-databases option is given.
--no-create-info, -t
Do not write CREATE TABLE statements
that re-create each dumped table.
--no-data, -d
Do not write any row information for the table. This is
very useful if you want to dump only the CREATE
TABLE statement for the table.
--opt
This option is shorthand; it is the same as specifying
--add-drop-table --add-locks --create-options
--disable-keys --extended-insert --lock-tables --quick
--set-charset. It should give you a fast dump
operation and produce a dump file that can be reloaded
into a MySQL server quickly.
This option is enabled by default, but can be
disabled with --skip-opt. To
disable only certain of the options enabled by
--opt, use their --skip
forms; for example, --skip-add-drop-table
or --skip-quick.
--order-by-primary
Sorts each table's rows by its primary key, or its first
unique index, if such an index exists. This is useful when
dumping a MyISAM table to be loaded
into an InnoDB table, but will make the
dump itself take considerably longer.
--password[=password],
-p[password]
The password to use when connecting to the server. If you
use the short option form (-p), you
cannot have a space between the
option and the password. If you omit the
password value following the
--password or -p option
on the command line, you are prompted for one.
Specifying a password on the command line should be
considered insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
--port=port_num,
-P port_num
The TCP/IP port number to use for the connection.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use.
--quick, -q
This option is useful for dumping large tables. It forces
mysqldump to retrieve rows for a table
from the server a row at a time rather than retrieving the
entire row set and buffering it in memory before writing
it out.
--quote-names, -Q
Quote database, table, and column names within
‘`’ characters. If the
ANSI_QUOTES SQL mode is enabled, names
are quoted within ‘"’
characters. This option is enabled by default. It can be
disabled with --skip-quote-names, but
this option should be given after any option such as
--compatible that may enable
--quote-names.
--result-file=file,
-r file
Direct output to a given file. This option should be used
on Windows to prevent newline
‘\n’ characters from being
converted to ‘\r\n’
carriage return/newline sequences.
--routines, -R
Dump stored routines (functions and procedures) from the
dumped databases. The output generated by using
--routines contains CREATE
PROCEDURE and CREATE FUNCTION
statements to re-create the routines. However, these
statements do not include attributes such as the routine
creation and modification timestamps. This means that when
the routines are reloaded, they will be created with the
timestamps equal to the reload time.
If you require routines to be re-created with their
original timestamp attributes, do not use
--routines. Instead, dump and reload the
contents of the mysql.proc table
directly, using a MySQL account that has appropriate
privileges for the mysql database.
This option was added in MySQL 5.0.13. Before that, stored
routines are not dumped. Routine
DEFINER values are not dumped until
MySQL 5.0.20. This means that before 5.0.20, when routines
are reloaded, they will be created with the definer set to
the reloading user. If you require routines to be
re-created with their original definer, dump and load the
contents of the mysql.proc table
directly as described earlier.
--set-charset
Add SET NAMES
default_character_set
to the output. This option is enabled by default. To
suppress the SET NAMES statement, use
--skip-set-charset.
--single-transaction
This option issues a BEGIN SQL
statement before dumping data from the server. It is
useful only with transactional tables such as
InnoDB and BDB,
because then it dumps the consistent state of the database
at the time when BEGIN was issued
without blocking any applications.
When using this option, you should keep in mind that only
InnoDB tables are dumped in a
consistent state. For example, any
MyISAM or HEAP
tables dumped while using this option may still change
state.
The --single-transaction option and the
--lock-tables option are mutually
exclusive, because LOCK TABLES causes
any pending transactions to be committed implicitly.
To dump big tables, you should combine this option with
--quick.
--socket=path,
-S path
For connections to localhost, the Unix
socket file to use, or, on Windows, the name of the named
pipe to use.
--skip-comments
See the description for the --comments
option.
--tab=path,
-T path
Produce tab-separated data files. For each dumped table,
mysqldump creates a
tbl_name.sqlCREATE TABLE
statement that creates the table, and a
tbl_name.txt
By default, the .txt data files are
formatted using tab characters between column values and a
newline at the end of each line. The format can be
specified explicitly using the
--fields-xxx
and
--lines--xxx
options.
Note: This option should
be used only when mysqldump is run on
the same machine as the mysqld server.
You must have the FILE privilege, and
the server must have permission to write files in the
directory that you specify.
--tables
Override the --databases or
-B option. All name arguments following
the option are regarded as table names.
--triggers
Dump triggers for each dumped table. This option is
enabled by default; disable it with
--skip-triggers. This option was added in
MySQL 5.0.11. Before that, triggers are not dumped.
--tz-utc
Add SET TIME_ZONE='+00:00' to the dump
file so that TIMESTAMP columns can be
dumped and reloaded between servers in different time
zones. Without this option, TIMESTAMP
columns are dumped and reloaded in the time zones local to
the source and destination servers, which can cause the
values to change. --tz-utc also protects
against changes due to daylight saving time.
--tz-utc is enabled by default. To
disable it, use --skip-tz-utc. This
option was added in MySQL 5.0.15.
--user=user_name,
-u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Print more information about what the
program does.
--version, -V
Display version information and exit.
--where='where_condition',
-w
'where_condition'
Dump only rows selected by the given
WHERE condition. Note that quotes
around the condition are mandatory if it contains spaces
or other characters that are special to your command
interpreter.
Examples:
--where="user='jimf'"
-w"userid>1"
-w"userid<1"
--xml, -X
Write dump output as well-formed XML.
You can also set the following variables by using
--var_name=value
syntax:
max_allowed_packet
The maximum size of the buffer for client/server
communication. The maximum is 1GB.
net_buffer_length
The initial size of the buffer for client/server
communication. When creating multiple-row-insert
statements (as with option
--extended-insert or
--opt), mysqldump
creates rows up to net_buffer_length
length. If you increase this variable, you should also
ensure that the net_buffer_length
variable in the MySQL server is at least this large.
It is also possible to set variables by using
--set-variable=var_name=value
or -O
var_name=value
syntax. This syntax is deprecated.
The most common use of mysqldump is
probably for making a backup of an entire database:
shell> mysqldump --opt db_name > backup-file.sql
You can read the dump file back into the server like this:
shell> mysql db_name < backup-file.sql
Or like this:
shell> mysql -e "source /path-to-backup/backup-file.sql" db_name
mysqldump is also very useful for
populating databases by copying data from one MySQL server to
another:
shell> mysqldump --opt db_name | mysql --host=remote_host -C db_name
It is possible to dump several databases with one command:
shell> mysqldump --databases db_name1 [db_name2 ...] > my_databases.sql
To dump all databases, use the
--all-databases option:
shell> mysqldump --all-databases > all_databases.sql
For InnoDB tables,
mysqldump provides a way of making an
online backup:
shell> mysqldump --all-databases --single-transaction > all_databases.sql
This backup just needs to acquire a global read lock on all
tables (using FLUSH TABLES WITH READ LOCK)
at the beginning of the dump. As soon as this lock has been
acquired, the binary log coordinates are read and the lock is
released. If and only if one long updating statement is
running when the FLUSH statement is issued,
the MySQL server may get stalled until that long statement
finishes, and then the dump becomes lock-free. If the update
statements that the MySQL server receives are short (in terms
of execution time), the initial lock period should not be
noticeable, even with many updates.
For point-in-time recovery (also known as
“roll-forward,” when you need to restore an old
backup and replay the changes that happened since that
backup), it is often useful to rotate the binary log (see
Section 5.12.3, “The Binary Log”) or at least know the binary log
coordinates to which the dump corresponds:
shell> mysqldump --all-databases --master-data=2 > all_databases.sql
Or:
shell> mysqldump --all-databases --flush-logs --master-data=2
> all_databases.sql
The simultaneous use of --master-data and
--single-transaction provides a convenient
way to make an online backup suitable for point-in-time
recovery if tables are stored in the InnoDB
storage engine.
For more information on making backups, see
Section 5.10.1, “Database Backups”, and
Section 5.10.2, “Example Backup and Recovery Strategy”.
8.11. mysqlhotcopy — A Database Backup Program
mysqlhotcopy is a Perl script that was
originally written and contributed by Tim Bunce. It uses
LOCK TABLES, FLUSH
TABLES, and cp or
scp to make a database backup quickly. It
is the fastest way to make a backup of the database or single
tables, but it can be run only on the same machine where the
database directories are located.
mysqlhotcopy works only for backing up
MyISAM and ARCHIVE
tables. It runs on Unix and NetWare.
shell> mysqlhotcopy db_name [/path/to/new_directory]
shell> mysqlhotcopy db_name_1 ... db_name_n /path/to/new_directory
Back up tables in the given database that match a regular
expression:
shell> mysqlhotcopy db_name./regex/
The regular expression for the table name can be negated by
prefixing it with a tilde
(‘~’):
shell> mysqlhotcopy db_name./~regex/
mysqlhotcopy supports the following
options:
--help, -?
Display a help message and exit.
--addtodest
Do not rename target directory (if it exists); merely add
files to it.
--allowold
Do not abort if a target exists; rename it by adding an
_old suffix.
--checkpoint=db_name.tbl_name
Insert checkpoint entries into the specified database
db_name and table
tbl_name.
--chroot=path
Base directory of the chroot jail in
which mysqld operates. The
path value should match that of
the --chroot option given to
mysqld.
--debug
Enable debug output.
--dryrun, -n
Report actions without performing them.
--flushlog
Flush logs after all tables are locked.
--host=host_name,
-h host_name
The hostname of the local host to use for making a TCP/IP
connection to the local server. By default, the connection
is made to localhost using a Unix
socket file.
--keepold
Do not delete previous (renamed) target when done.
--method=command
The method for copying files (cp or
scp).
--noindices
Do not include full index files in the backup. This makes
the backup smaller and faster. The indexes for reloaded
tables can be reconstructed later with myisamchk
-rq.
--password=password,
-ppassword
The password to use when connecting to the server. Note
that the password value is not optional for this option,
unlike for other MySQL programs. You can use an option
file to avoid giving the password on the command line.
Specifying a password on the command line should be
considered insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
--port=port_num,
-P port_num
The TCP/IP port number to use when connecting to the local
server.
--quiet, -q
Be silent except for errors.
--record_log_pos=db_name.tbl_name
Record master and slave status in the specified database
db_name and table
tbl_name.
--regexp=expr
Copy all databases with names that match the given regular
expression.
--resetmaster
Reset the binary log after locking all the tables.
--resetslave
Reset the master.info file after
locking all the tables.
--socket=path,
-S path
The Unix socket file to use for the connection.
--suffix=str
The suffix for names of copied databases.
--tmpdir=path
The temporary directory. The default is
/tmp.
--user=user_name,
-u user_name
The MySQL username to use when connecting to the server.
mysqlhotcopy reads the
[client] and
[mysqlhotcopy] option groups from option
files.
To execute mysqlhotcopy, you must have
access to the files for the tables that you are backing up,
the SELECT privilege for those tables, and
the RELOAD privilege (to be able to execute
FLUSH TABLES).
Use perldoc for additional
mysqlhotcopy documentation, including
information about the structure of the tables needed for the
--checkpoint and
--record_log_pos options:
shell> perldoc mysqlhotcopy
8.12. mysqlimport — A Data Import Program
The mysqlimport client provides a
command-line interface to the LOAD DATA
INFILE SQL statement. Most options to
mysqlimport correspond directly to clauses
of LOAD DATA INFILE syntax. See
Section 13.2.5, “LOAD DATA INFILE Syntax”.
Invoke mysqlimport like this:
shell> mysqlimport [options] db_name textfile1 [textfile2 ...]
For each text file named on the command line,
mysqlimport strips any extension from the
filename and uses the result to determine the name of the
table into which to import the file's contents. For example,
files named patient.txt,
patient.text, and
patient all would be imported into a
table named patient.
mysqlimport supports the following options:
--help, -?
Display a help message and exit.
--character-sets-dir=path
The directory where character sets are installed. See
Section 5.11.1, “The Character Set Used for Data and Sorting”.
--columns=column_list,
-c column_list
This option takes a comma-separated list of column names
as its value. The order of the column names indicates how
to match data file columns with table columns.
--compress, -C
Compress all information sent between the client and the
server if both support compression.
--debug[=debug_options],
-#
[debug_options]
Write a debugging log. The
debug_options string often is
'd:t:o,file_name'.
--default-character-set=charset_name
Use charset_name as the default
character set. See Section 5.11.1, “The Character Set Used for Data and Sorting”.
--delete, -D
Empty the table before importing the text file.
--fields-terminated-by=...,
--fields-enclosed-by=...,
--fields-optionally-enclosed-by=...,
--fields-escaped-by=...,
--lines-terminated-by=...
These options have the same meaning as the corresponding
clauses for LOAD DATA INFILE. See
Section 13.2.5, “LOAD DATA INFILE Syntax”.
--force, -f
Ignore errors. For example, if a table for a text file
does not exist, continue processing any remaining files.
Without --force,
mysqlimport exits if a table does not
exist.
--host=host_name,
-h host_name
Import data to the MySQL server on the given host. The
default host is localhost.
--ignore, -i
See the description for the --replace
option.
--ignore-lines=N
Ignore the first N lines of the
data file.
--local, -L
Read input files locally from the client host.
--lock-tables, -l
Lock all tables for writing before
processing any text files. This ensures that all tables
are synchronized on the server.
--low-priority
Use LOW_PRIORITY when loading the
table.
--password[=password],
-p[password]
The password to use when connecting to the server. If you
use the short option form (-p), you
cannot have a space between the
option and the password. If you omit the
password value following the
--password or -p option
on the command line, you are prompted for one.
Specifying a password on the command line should be
considered insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
--port=port_num,
-P port_num
The TCP/IP port number to use for the connection.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use.
--replace, -r
The --replace and
--ignore options control handling of
input rows that duplicate existing rows on unique key
values. If you specify --replace, new
rows replace existing rows that have the same unique key
value. If you specify --ignore, input
rows that duplicate an existing row on a unique key value
are skipped. If you do not specify either option, an error
occurs when a duplicate key value is found, and the rest
of the text file is ignored.
--silent, -s
Silent mode. Produce output only when errors occur.
--socket=path,
-S path
For connections to localhost, the Unix
socket file to use, or, on Windows, the name of the named
pipe to use.
--user=user_name,
-u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Print more information about what the
program does.
--version, -V
Display version information and exit.
Here is a sample session that demonstrates use of
mysqlimport:
shell> mysql -e 'CREATE TABLE imptest(id INT, n VARCHAR(30))' test
shell> ed
a
100 Max Sydow
101 Count Dracula
.
w imptest.txt
32
q
shell> od -c imptest.txt
0000000 1 0 0 \t M a x S y d o w \n 1 0
0000020 1 \t C o u n t D r a c u l a \n
0000040
shell> mysqlimport --local test imptest.txt
test.imptest: Records: 2 Deleted: 0 Skipped: 0 Warnings: 0
shell> mysql -e 'SELECT * FROM imptest' test
+------+---------------+
| id | n |
+------+---------------+
| 100 | Max Sydow |
| 101 | Count Dracula |
+------+---------------+
8.13. mysqlshow — Display Database, Table, and Column Information
The mysqlshow client can be used to quickly
see which databases exist, their tables, or a table's columns
or indexes.
mysqlshow provides a command-line interface
to several SQL SHOW statements. See
Section 13.5.4, “SHOW Syntax”. The same information can be obtained
by using those statements directly. For example, you can issue
them from the mysql client program.
Invoke mysqlshow like this:
shell> mysqlshow [options] [db_name [tbl_name [col_name]]]
If no database is given, a list of database names is
shown.
If no table is given, all matching tables in the database
are shown.
If no column is given, all matching columns and column
types in the table are shown.
The output displays only the names of those databases, tables,
or columns for which you have some privileges.
If the last argument contains shell or SQL wildcard characters
(‘*’,
‘?’,
‘%’, or
‘_’), only those names that are
matched by the wildcard are shown. If a database name contains
any underscores, those should be escaped with a backslash
(some Unix shells require two) to get a list of the proper
tables or columns. ‘*’ and
‘?’ characters are converted
into SQL ‘%’ and
‘_’ wildcard characters. This
might cause some confusion when you try to display the columns
for a table with a ‘_’ in the
name, because in this case, mysqlshow shows
you only the table names that match the pattern. This is
easily fixed by adding an extra
‘%’ last on the command line as
a separate argument.
mysqlshow supports the following options:
--help, -?
Display a help message and exit.
--character-sets-dir=path
The directory where character sets are installed. See
Section 5.11.1, “The Character Set Used for Data and Sorting”.
--compress, -C
Compress all information sent between the client and the
server if both support compression.
--count
Show the number of rows per table. This can be slow for
non-MyISAM tables. This option was
added in MySQL 5.0.6.
--debug[=debug_options],
-#
[debug_options]
Write a debugging log. The
debug_options string often is
'd:t:o,file_name'.
--default-character-set=charset_name
Use charset_name as the default
character set. See Section 5.11.1, “The Character Set Used for Data and Sorting”.
--host=host_name,
-h host_name
Connect to the MySQL server on the given host.
--keys, -k
Show table indexes.
--password[=password],
-p[password]
The password to use when connecting to the server. If you
use the short option form (-p), you
cannot have a space between the
option and the password. If you omit the
password value following the
--password or -p option
on the command line, you are prompted for one.
Specifying a password on the command line should be
considered insecure. See
Section 5.9.6, “Keeping Your Password Secure”.
--port=port_num,
-P port_num
The TCP/IP port number to use for the connection.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use.
--show-table-type, -t
Show a column indicating the table type, as in
SHOW FULL TABLES. The type is
BASE TABLE or VIEW.
This option was added in MySQL 5.0.4.
--socket=path,
-S path
For connections to localhost, the Unix
socket file to use, or, on Windows, the name of the named
pipe to use.
--status, -i
Display extra information about each table.
--user=user_name,
-u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Print more information about what the
program does. This option can be used multiple times to
increase the amount of information.
--version, -V
Display version information and exit.
8.14. mysql_zap — Kill Processes That Match a Pattern
mysql_zap kills processes that match a
pattern. It uses the ps command and Unix
signals, so it runs on Unix and Unix-like systems.
Invoke mysql_zap like this:
shell> mysql_zap [-signal] [-?Ift] pattern
A process matches if its output line from the
ps command contains the pattern. By
default, mysql_zap asks for confirmation
for each process. Respond y to kill the
process, or q to exit
mysql_zap. For any other response,
mysql_zap does not attempt to kill the
process.
If the -signal
option is given, it specifies the name or number of the signal
to send to each process. Otherwise,
mysql_zap tries first with
TERM (signal 15) and then with
KILL (signal 9).
mysql_zap understands the following
additional options:
--help, -?,
-I
Display a help message and exit.
-f
Force mode. mysql_zap attempts to kill
each process without confirmation.
-t
Test mode. Display information about each process but do
not kill it.
8.15. perror — Explain Error Codes
For most system errors, MySQL displays, in addition to an
internal text message, the system error code in one of the
following styles:
message ... (errno: #)
message ... (Errcode: #)
You can find out what the error code means by examining the
documentation for your system or by using the
perror utility.
perror prints a description for a system
error code or for a storage engine (table handler) error code.
Invoke perror like this:
shell> perror [options] errorcode ...
Example:
shell> perror 13 64
Error code 13: Permission denied
Error code 64: Machine is not on the network
To obtain the error message for a MySQL Cluster error code,
invoke perror with the
--ndb option:
shell> perror --ndb errorcode
Note that the meaning of system error messages may be
dependent on your operating system. A given error code may
mean different things on different operating systems.
perror supports the following options:
--help, --info,
-I, -?
Display a help message and exit.
--ndb
Print the error message for a MySQL Cluster error code.
--silent, -s
Silent mode. Print only the error message.
--verbose, -v
Verbose mode. Print error code and message. This is the
default behavior.
--version, -V
Display version information and exit.
8.16. replace — A String-Replacement Utility
The replace utility program changes strings
in place in files or on the standard input.
Invoke replace in one of the following
ways:
shell> replace from to [from to] ... -- file [file] ...
shell> replace from to [from to] ... < input
from represents a string to look
for and to represents its
replacement. There can be one or more pairs of strings.
Use the -- option to indicate where the
string-replacement list ends and the filenames begin. In this
case, any file named on the command line is modified in place,
so you may want to make a copy of the original before
converting it. replace prints a
message indicating which of the input files it actually
modifies.
If the -- option is not given
replace reads the standard input and writes
to the standard output.
replace uses a finite state machine to
match longer strings first. It can be used to swap strings.
For example, the following command swaps a
and b in the given files,
file1 and file2:
shell> replace a b b a -- file1 file2 ...
The replace program is used by
msql2mysql. See
Section 22.9.1, “msql2mysql — Convert mSQL Programs for Use with MySQL”.
replace supports the following options:
-?, -I
Display a help message and exit.
-#
debug_options
Write a debugging log. The
debug_options'd:t:o,file_name'.
-s
Silent mode. Print less information what the program does.
-v
Verbose mode. Print more information about what the
program does.
-V
Display version information and exit.
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