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All MySQL clients that communicate with the server using the
mysqlclient library use the following environment variables:
| Name | Description |
MYSQL_UNIX_PORT | The default socket; used for connections to localhost
|
MYSQL_TCP_PORT | The default TCP/IP port |
MYSQL_PWD | The default password |
MYSQL_DEBUG | Debug-trace options when debugging |
TMPDIR | The directory where temporary tables/files are created |
Use of MYSQL_PWD is insecure.
See section 6.5 Connecting to the MySQL server.
The `mysql' client uses the file named in the MYSQL_HISTFILE
environment variable to save the command line history. The default value for
the history file is `$HOME/.mysql_history', where $HOME is the
value of the HOME environment variable. See section A Environment variables.
All MySQL programs take many different options. However, every
MySQL program provides a --help option that you can use
to get a full description of the program's different options. For example, try
mysql --help.
You can override default options for all standard client programs with an option file. section 4.15.5 Option files.
The list below briefly describes the MySQL programs:
myisamchk
myisamchk has many functions, it is described in its own
chapter. See section 15 Maintaining a MySQL installation.
make_binary_release
ftp.tcx.se for the
convenience of other MySQL users.
msql2mysql
mSQL programs to MySQL. It doesn't
handle all cases, but it gives a good start when converting.
mysqlaccess
mysqladmin
mysqladmin can also be used to retrieve version,
process and status information from the server.
See section 14.3 Administering a MySQL server.
mysqlbug
mysqld
mysqldump
mysqlimport
LOAD DATA
INFILE. See section 14.5 Importing data from text files.
mysqlshow
mysql_install_db
replace
msql2mysql, but that has more
general applicability as well. replace changes strings in place in
files or on the standard input. Uses a finite state machine to match longer
strings first. Can be used to swap strings. For example, this command
swaps a and b in the given files:
shell> replace a b b a -- file1 file2 ...
safe_mysqld
mysqld daemon with some safety features, such
as restarting the server when an error occurs and logging runtime information
to a log file.
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 (e.g., as a filter), the result is presented in
tab-separated format. (The output format can be changed using command-line
options.) You can run scripts simply like this:
shell> mysql database < script.sql > output.tab
If you have problems due to insufficient memory in the client, use the
--quick option! This forces mysql to use
mysql_use_result() rather than mysql_store_result() to
retrieve the result set.
Using mysql is very easy; Just start it as follows
mysql database or mysql --user=user_name --password=your_password database. Type a SQL statement, end it with `;', `g' or `G'
and press return/enter.
mysql supports the following options:
-?, --help
-A, --no-auto-rehash
-B, --batch
-C, --compress
-#, --debug[=...]
-D, --database=..
my.cnf file.
-e, --execute=...
-E, --vertical
G.
-f, --force
-i, --ignore-space
-h, --host=...
-H, --html
-L, --skip-line-numbers
-n, --unbuffered
-N, --skip-column-names
-O, --set-variable var=option
--help lists variables.
-o, --one-database
-p[password], --password[=...]
-p you can't have a space between the option and the
password.
-P --port=...
-q, --quick
-r, --raw
--batch
-s, --silent
-S --socket=...
-t --table
-T, --exit-info
-u, --user=#
-U, --safe-updates[=#], --i-am-a-dummy[=#]
UPDATE and DELETE that uses keys. See below for
more information about this option. You can reset this option if you have
it in your my.cnf file by using --safe-updates=0.
-v, --verbose
-V, --version
-w, --wait
If you type 'help' on the command line, mysql will print out the
commands that it supports:
mysql> help MySQL commands: help (h) Display this text ? (h) Synonym for `help' clear (c) Clear command connect (r) Reconnect to the server. Optional arguments are db and host edit (e) Edit command with $EDITOR exit (q) Exit mysql. Same as quit go (g) Send command to mysql server ego (G) Send command to mysql server; Display result vertically print (p) Print current command quit (q) Quit mysql rehash (#) Rebuild completion hash source (.) Execute a SQL script file. Takes a file name as an argument status (s) Get status information from the server use (u) Use another database. Takes database name as argument
The status command gives you some information about the
connection and the server you are using. If you are running in the
--safe-updates mode, status will also print the values for
the mysql variables that affects your queries.
A useful startup option for beginners (introduced in MySQL 3.23.11) is
--safe-mode (or --i-am-a-dummy for users that has at some
time done a DELETE FROM table_name but forgot the WHERE
clause. When using this option, mysql sends the following
command to the MySQL server when opening the connection:
SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=#select_limit#,
SQL_MAX_JOIN_SIZE=#max_join_size#"
where #select_limit# and #max_join_size# are variables that
can be set from the mysql command line. See section 7.28 SET syntax.
The effect of the above is:
UPDATE or DELETE statements
if you don't have a key constraint in the WHERE part. One can
however force an UPDATE/DELETE by using LIMIT:
UPDATE table_name SET not_key_column=# WHERE not_key_column=# LIMIT 1;
#select_limit# rows.
SELECT's that will probably need to examine more than
#max_join_size row combinations will be aborted.
Utility for performing administrative operations. The syntax is:
shell> mysqladmin [OPTIONS] command [command-option] command ...
You can get a list of the options your version of mysqladmin supports
by executing mysqladmin --help.
The current mysqladmin supports the following commands:
| create databasename | Create a new database. |
| drop databasename | Delete a database and all its tables. |
| extended-status | Gives an extended status message from the server. |
| flush-hosts | Flush all cached hosts. |
| flush-logs | Flush all logs. |
| flush-tables | Flush all tables. |
| flush-privileges | Reload grant tables (same as reload). |
| kill id,id,... | Kill mysql threads. |
| password | new-password Change old password to new-password. |
| ping | Check if mysqld is alive. |
| processlist | Show list of active threads in server. |
| reload | Reload grant tables. |
| refresh | Flush all tables and close and open logfiles. |
| shutdown | Take server down. |
| slave-start | Start slave replication thread. |
| slave-stop | Stop slave replication thread. |
| status | Gives a short status message from the server. |
| variables | Prints variables available. |
| version | Get version info from server. |
All commands can be shortened to their unique prefix. For example:
shell> mysqladmin proc stat +----+-------+-----------+----+-------------+------+-------+------+ | Id | User | Host | db | Command | Time | State | Info | +----+-------+-----------+----+-------------+------+-------+------+ | 6 | monty | localhost | | Processlist | 0 | | | +----+-------+-----------+----+-------------+------+-------+------+ Uptime: 10077 Threads: 1 Questions: 9 Slow queries: 0 Opens: 6 Flush tables: 1 Open tables: 2 Memory in use: 1092K Max memory used: 1116K
The mysqladmin status command result has the following columns:
| Uptime | Number of seconds the MySQL server has been up. |
| Threads | Number of active threads (clients). |
| Questions | Number of questions from clients since mysqld was started.
|
| Slow queries | Queries that have taken more than long_query_time seconds.
|
| Opens | How many tables mysqld has opened.
|
| Flush tables | Number of flush ..., refresh and reload commands.
|
| Open tables | Number of tables that are open now. |
| Memory in use | Memory allocated directly by the mysqld code (only available when MySQL is compiled with --with-debug). |
| Max memory used | Maximum memory allocated directly by the mysqld code (only available when MySQL is compiled with --with-debug). |
If you do myslqadmin shutdown on a socket (in other words, on a
the computer where mysqld is running), mysqladmin will
wait until the MySQL pid-file is removed to ensure that
the mysqld server has stopped properly.
Utility to dump a database or a collection of database for backup or for transferring the data to another SQL server. The dump will contain SQL statements to create the table and/or populate the table.
shell> mysqldump [OPTIONS] database [tables] OR mysqldump [OPTIONS] --databases [OPTIONS] DB1 [DB2 DB3...] OR mysqldump [OPTIONS] --all-databases [OPTIONS]
If you don't give any tables or use the --databases or
--all-databases, the whole database(s) will be dumped.
You can get a list of the options your version of mysqldump supports
by executing mysqldump --help.
Note that if you run mysqldump without --quick or
--opt, mysqldump will load the whole result set into
memory before dumping the result. This will probably be a problem if
you are dumping a big database.
mysqldump supports the following options:
--add-locks
LOCK TABLES before and UNLOCK TABLE after each table dump.
(To get faster inserts into MySQL).
--add-drop-table
drop table before each create statement.
-A, --all-databases
--databases with all
databases selected.
-a, --all
--allow-keywords
-c, --complete-insert
-C, --compress
-B, --databases
USE db_name; will be included in the output before each new database.
--delayed
INSERT DELAYED command.
-e, --extended-insert
INSERT syntax. (Gives more compact and
faster inserts statements.)
-#, --debug[=option_string]
--help
--fields-terminated-by=...
--fields-enclosed-by=...
--fields-optionally-enclosed-by=...
--fields-escaped-by=...
--lines-terminated-by=...
-T option and have the same
meaning as the corresponding clauses for LOAD DATA INFILE.
See section 7.18 LOAD DATA INFILE syntax.
-F, --flush-logs
-f, --force,
-h, --host=..
localhost.
-l, --lock-tables.
READ LOCAL to allow concurrent inserts in the case of MyISAM
tables.
-n, --no-create-db
-t, --no-create-info
CREATE TABLE statement.)
-d, --no-data
--opt
--quick --add-drop-table --add-locks --extended-insert
--lock-tables. Should give you the fastest possible dump for reading
into a MySQL server.
-pyour_pass, --password[=your_pass]
mysqldump you will be prompted for a password.
-P port_num, --port=port_num
localhost, for which Unix sockets are
used.)
-q, --quick
mysql_use_result()
to do this.
-S /path/to/socket, --socket=/path/to/socket
localhost (which is the
default host).
--tables
-T, --tab=path-to-some-directory
table_name.sql file, that contains the SQL CREATE commands,
and a table_name.txt file, that contains the data, for each give table.
NOTE: This only works if mysqldump is run on the same
machine as the mysqld daemon. The format of the .txt file
is made according to the --fields-xxx and --lines--xxx options.
-u user_name, --user=user_name
-O var=option, --set-variable var=option
-v, --verbose
-V, --version
-w, --where='where-condition'
"--where=user='jimf'" "-wuserid>1" "-wuserid<1"
-O net_buffer_length=#, where # < 24M
--extended-insert or --opt), mysqldump will create
rows up to net_buffer_length length. If you increase this
variable, you should also ensure that the max_allowed_packet
variable in the MySQL server is bigger than the
net_buffer_length.
The most normal use of mysqldump is probably for making a backup of
whole databases. See section 21.2 Database backups.
mysqldump --opt database > backup-file.sql
However, it's also very useful to populate another MySQL server with information from a database:
mysqldump --opt database | mysql --host=remote-host -C database
It is possible to dump several databases with one command:
mysqldump --databases database1 [database2 database3...] > my_databases.sql
If all the databases are wanted, one can use:
mysqldump --all-databases > all_databases.sql
mysqlimport provides a command line interface to the LOAD DATA
INFILE SQL statement. Most options to mysqlimport correspond
directly to the same options to LOAD DATA INFILE.
See section 7.18 LOAD DATA INFILE syntax.
mysqlimport is invoked like this:
shell> mysqlimport [options] database textfile1 [textfile2....]
For each text file named on the command line,
mysqlimport strips any extension from the filename and uses the result
to determine which table to import the file's contents into. For example,
files named `patient.txt', `patient.text' and `patient' would
all be imported into a table named patient.
mysqlimport supports the following options:
-c, --columns=...
LOAD DATA INFILE. See section 7.18 LOAD DATA INFILE syntax.
-C, --compress
-#, --debug[=option_string]
-d, --delete
--fields-terminated-by=...
--fields-enclosed-by=...
--fields-optionally-enclosed-by=...
--fields-escaped-by=...
--lines-terminated-by=...
LOAD DATA INFILE. See section 7.18 LOAD DATA INFILE syntax.
-f, --force
--force,
mysqlimport exits if a table doesn't exist.
--help
-h host_name, --host=host_name
localhost.
-i, --ignore
--replace option.
-l, --lock-tables
-L, --local
localhost (which is the default host).
-pyour_pass, --password[=your_pass]
mysqlimport you will be prompted for a password.
-P port_num, --port=port_num
localhost, for which Unix sockets are
used.)
-r, --replace
--replace and --ignore options control handling of input
records that duplicate existing records 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 don't specify either option, an
error occurs when a duplicate key value is found, and the rest of the text
file is ignored.
-s, --silent
-S /path/to/socket, --socket=/path/to/socket
localhost (which is the
default host).
-u user_name, --user=user_name
-v, --verbose
-V, --version
Here follows a sample run of using mysqlimport:
$ mysql --version mysql Ver 9.33 Distrib 3.22.25, for pc-linux-gnu (i686) $ uname -a Linux xxx.com 2.2.5-15 #1 Mon Apr 19 22:21:09 EDT 1999 i586 unknown $ mysql -e 'CREATE TABLE imptest(id INT, n VARCHAR(30))' test $ ed a 100 Max Sydow 101 Count Dracula . w imptest.txt 32 q $ 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 $ mysqlimport --local test imptest.txt test.imptest: Records: 2 Deleted: 0 Skipped: 0 Warnings: 0 $ mysql -e 'SELECT * FROM imptest' test +------+---------------+ | id | n | +------+---------------+ | 100 | Max Sydow | | 101 | Count Dracula | +------+---------------+
mysqlshow can be used to quickly look at which databases exist,
their tables, and the table's columns.
With the mysql program you can get the same information with the
SHOW commands. See section 7.23 SHOW syntax (Get information about tables, columns,...).
mysqlshow is invoked like this:
shell> mysqlshow [OPTIONS] [database [table [column]]]
Note that in newer MySQL versions you only see those database/tables/columns for which you have some privileges.
If the last argument contains a shell or SQL wildcard (*, ?,
% or _) then only what's matched by the wildcard is shown.
This may cause some confusion when you try to display the columns for a
table with a _ as in this case mysqlshow only shows you
the table names that matches the pattern. This is easily fixed by
adding an extra % last on the command line (as a separate
argument).
myisampack is used to compress MyISAM tables and pack_isam
is used to compress ISAM tables. Because ISAM tables are deprecated, we
will only discuss myisampack here, but everything said about
myisampack should also be true for pack_isam.
myisampack works by compressing each column in the table separately.
The information needed to decompress columns is read into memory when the
table is opened. This results in much better performance when accessing
individual records, because you only have to uncompress exactly one record, not
a much larger disk block like when using Stacker on MS-DOS.
Usually, myisampack packs the data file 40%-70%.
MySQL uses memory mapping (mmap()) on compressed tables and
falls back to normal read/write file usage if mmap() doesn't work.
There are currently two limitations with myisampack:
myisampack can also pack BLOB or TEXT columns. The
older pack_isam could not do this.
Fixing these limitations is on our TODO list but with low priority.
myisampack is invoked like this:
shell> myisampack [options] filename ...
Each filename 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.
myisampack supports the following options:
-b, --backup
tbl_name.OLD.
-#, --debug=debug_options
debug_options string often is
'd:t:o,filename'.
-f, --force
myisampack creates a temporary file named `tbl_name.TMD'
while it compresses the table. If you kill myisampack, the `.TMD'
file may not be deleted. Normally, myisampack exits with an error if
it finds that `tbl_name.TMD' exists. With --force,
myisampack packs the table anyway.
-?, --help
-j big_tbl_name, --join=big_tbl_name
big_tbl_name. All tables that are to be combined
MUST be identical (same column names and types, same indexes, etc.).
-p #, --packlength=#
myisampack stores all rows with length pointers of 1, 2 or 3
bytes. In most normal cases, myisampack can determine the right 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 will print a note that the next time you pack the same file,
you could use a shorter record length.)
-s, --silent
-t, --test
-T dir_name, --tmp_dir=dir_name
-v, --verbose
-V, --version
-w, --wait
mysqld server was
invoked with the --skip-locking option, it is not a good idea to
invoke myisampack if the table might be updated during the
packing process.
The sequence of commands shown below 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% 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 Datafilepointer (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
The information printed by myisampack is described below:
normal
empty-space
empty-zero
empty-fill
INTEGER
column may be changed to MEDIUMINT).
pre-space
end-space
table-lookup
ENUM before Huffman compression.
zero
Original trees
After join
After a table has been compressed, myisamchk -dvv prints additional
information about each field:
Type
constant
no endspace
no endspace, not_always
no endspace, no empty
table-lookup
ENUM.
zerofill(n)
n bytes in the value are always 0 and are not
stored.
no zeros
always zero
Huff tree
Bits
After you have run pack_isam/myisampack you must run
isamchk/myisamchk to recreate the index. At this time you
can also sort the index blocks and create statistics that is needed for
the MySQL optimizer to work more efficiently.
myisamchk -rq --analyze --sort-index table_name.MYI isamchk -rq --analyze --sort-index table_name.ISM
After you have installed the packed table into the MySQL database
directory you should do mysqladmin flush-tables to force mysqld
to start using the new table.
Go to the first, previous, next, last section, table of contents.
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