mariadb Command-Line Client

You are viewing an old version of this article. View the current version here.

mariadb is a simple SQL shell (with GNU readline capabilities).

MariaDB starting with 10.4.6

From MariaDB 10.4.6, mariadb is a symlink to mysql, the command-line client.

MariaDB starting with 10.5.2

From MariaDB 10.5.2, mariadb is the name of the command-line client, with mysql a symlink .

Contents

  1. About the mariadb Command-Line Client
  2. Using mariadb
    1. Options
      1. -?, --help
      2. -I, --help
      3. --abort-source-on-error
      4. --auto-rehash
      5. -A, --no-auto-rehash
      6. --auto-vertical-output
      7. -B, --batch
      8. --binary-mode
      9. --character-sets-dir=name
      10. --column-names
      11. --column-type-info
      12. -c, --comments
      13. -C, --compress
      14. --connect-expired-password
      15. --connect-timeout=num
      16. -D, --database=name
      17. -# [options], --debug[=options]
      18. --debug-check
      19. -T, --debug-info
      20. --default-auth=plugin
      21. --default-character-set=name
      22. --defaults-extra-file=file
      23. --defaults-file=file
      24. --defaults-group-suffix=suffix
      25. --delimiter=name
      26. --enable-cleartext-plugin
      27. -e, --execute=name
      28. -f, --force
      29. -h, --host=name
      30. -H, --html
      31. -U, --i-am-a-dummy
      32. -i, --ignore-spaces
      33. --init-command=str
      34. --line-numbers
      35. --local-infile
      36. --max-allowed-packet=num
      37. --max-join-size=num
      38. -G, --named-commands
      39. --net-buffer-length=num
      40. -b, --no-beep
      41. --no-defaults
      42. -o, --one-database
      43. --pager[=name]
      44. -p, --password[=name]
      45. --plugin-dir=name
      46. -P, --port=num
      47. --print-defaults
      48. --progress-reports
      49. --prompt=name
      50. --protocol=name
      51. -q, --quick
      52. -r, --raw
      53. --reconnect
      54. -U, --safe-updates
      55. --secure-auth
      56. --select-limit=num
      57. --server-arg=name
      58. --shared-memory-base-name=name
      59. --show-warnings
      60. --sigint-ignore
      61. -s, --silent
      62. --skip-auto-rehash
      63. -N, --skip-column-names
      64. --skip-comments
      65. -L, --skip-line-numbers
      66. --skip-progress-reports
      67. --skip-reconnect
      68. -S, --socket=name
      69. --ssl
      70. --ssl-ca=name
      71. --ssl-capath=name
      72. --ssl-cert=name
      73. --ssl-cipher=name
      74. --ssl-crl=name
      75. --ssl-crlpath=name
      76. --ssl-key=name
      77. --ssl-verify-server-cert
      78. -t, --table
      79. --tee=name
      80. --tls-version=name
      81. --tls-fp=name
      82. --tls-fplist=name
      83. -n, --unbuffered
      84. -u, --user=name
      85. -v, --verbose
      86. -V, --version
      87. -E, --vertical
      88. -w, --wait
      89. -X, --xml
    2. Option Files
      1. Option Groups
  3. How to Specify Which Protocol to Use When Connecting to the Server
    1. Linux/Unix
    2. Windows
  4. How to Test Which Protocol is Used
  5. mariadb Commands
  6. The mysql_history File
  7. prompt Command
  8. mariadb Tips
    1. Displaying Query Results Vertically
    2. Using the --safe-updates Option
    3. Disabling mariadb Auto-Reconnect
  9. See Also

About the mariadb Command-Line Client

mariadb 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 mariadb 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 mariadb is very easy. Invoke it from the prompt of your command interpreter as follows:

mariadb db_name

Or:

mariadb --user=user_name --password=your_password db_name

Then type an SQL statement, end it with “;”, \g, or \G and press Enter.

Typing Control-C causes mariadb to attempt to kill the current statement. If this cannot be done, or Control-C is typed again before the statement is killed, mariadb exits.

You can execute SQL statements in a script file (batch file) like this:

mariadb db_name < script.sql > output.tab

Using mariadb

The command to use mariadb and the general syntax is:

mariadb <options>

Options

mariadb supports the following options:

-?, --help

Display help and exit.

-I, --help

Synonym for -?

--abort-source-on-error

Abort 'source filename' operations in case of errors.

--auto-rehash

Enable automatic rehashing. This option is on by default, which enables database, table, and column name completion. Use --disable-auto-rehash, --no-auto-rehash or skip-auto-rehash to disable rehashing. That causes mariadb to start faster, but you must issue the rehash command if you want to use name completion. To complete a name, enter the first part and press Tab. If the name is unambiguous, mariadb completes it. Otherwise, you can press Tab again to see the possible names that begin with what you have typed so far. Completion does not occur if there is no default database.

-A, --no-auto-rehash

No automatic rehashing. One has to use 'rehash' to get table and field completion. This gives a quicker start of mariadb and disables rehashing on reconnect.

--auto-vertical-output

Automatically switch to vertical output mode if the result is wider than the terminal width.

-B, --batch

Print results using tab as the column separator, with each row on a new line. With this option, mariadb does not use the history file. Batch mode results in nontabular output format and escaping of special characters. Escaping may be disabled by using raw mode; see the description for the --raw option. (Enables --silent.)

--binary-mode

By default, ASCII '\0' is disallowed and '\r\n' is translated to '\n'. This switch turns off both features, and also turns off parsing of all client commands except \C and DELIMITER, in non-interactive mode (for input piped to mariadb or loaded using the 'source' command). This is necessary when processing output from mariadb-binlog that may contain blobs.

--character-sets-dir=name

Directory for character set files.

--column-names

Write column names in results. (Defaults to on; use --skip-column-names to disable.)

--column-type-info

Display column type information.

-c, --comments

Preserve comments. Send comments to the server. The default is --skip-comments (discard comments), enable with --comments.

-C, --compress

Compress all information sent between the client and the server if both support compression.

--connect-expired-password

Notify the server that this client is prepared to handle expired password sandbox mode even if --batch was specified. From MariaDB 10.4.3.

--connect-timeout=num

Number of seconds before connection timeout. Defaults to zero.

-D, --database=name

Database to use.

-# [options], --debug[=options]

On debugging builds, write a debugging log. A typical debug_options string is d:t:o,file_name. The default is d:t:o,/tmp/mysql.trace.

--debug-check

Check memory and open file usage at exit.

-T, --debug-info

Print some debug info at exit.

--default-auth=plugin

Default authentication client-side plugin to use.

--default-character-set=name

Set the default character set. A common issue that can occur when the operating system uses utf8 or another multibyte character set is that output from the mariadb client is formatted incorrectly, due to the fact that the MariaDB client uses the latin1 character set by default. You can usually fix such issues by using this option to force the client to use the system character set instead. If set to auto the character set is taken from the client environment (LC_CTYPE on Unix).

--defaults-extra-file=file

Read this file after the global files are read. Must be given as the first option.

--defaults-file=file

Only read default options from the given file. Must be given as the first option.

--defaults-group-suffix=suffix

In addition to the given groups, also read groups with this suffix.

--delimiter=name

Delimiter to be used. The default is the semicolon character (“;”).

--enable-cleartext-plugin

Obsolete option. Exists only for MySQL compatibility. From MariaDB 10.3.36.

-e, --execute=name

Execute statement and quit. Disables --force and history file. The default output format is like that produced with --batch.

-f, --force

Continue even if we get an SQL error. Sets --abort-source-on-error to 0.

-h, --host=name

Connect to host.

-H, --html

Produce HTML output.

-U, --i-am-a-dummy

Synonym for option --safe-updates, -U.

-i, --ignore-spaces

Ignore space after function names. Allows one to have spaces (including tab characters and new line characters) between function name and '('. The drawback is that this causes built in functions to become reserved words.

--init-command=str

SQL Command to execute when connecting to the MariaDB server. Will automatically be re-executed when reconnecting.

--line-numbers

Write line numbers for errors. (Defaults to on; use --skip-line-numbers to disable.)

--local-infile

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.

--max-allowed-packet=num

The maximum packet length to send to or receive from server. The default is 16MB, the maximum 1GB.

--max-join-size=num

Automatic limit for rows in a join when using --safe-updates. Default is 1000000.

-G, --named-commands

Enable named commands. Named commands mean mariadb's internal commands (see below) . When enabled, the named commands can be used from any line of the query, otherwise only from the first line, before an enter. Long-format commands are allowed, not just short-format commands. For example, quit and \q are both recognized. Disable with --disable-named-commands. This option is disabled by default.

--net-buffer-length=num

The buffer size for TCP/IP and socket communication. Default is 16KB.

-b, --no-beep

Turn off beep on error.

--no-defaults

Don't read default options from any option file. Must be given as the first option.

-o, --one-database

Ignore statements except those those that occur while the default database is the one named on the command line. This filtering is limited, and based only on USE statements. This is useful for skipping updates to other databases in the binary log.

--pager[=name]

Pager to use to display results (Unix only). If you don't supply an option, the default pager is taken from your ENV variable PAGER. Valid pagers are less, more, cat [> filename], etc. See interactive help (\h) also. This option does not work in batch mode. Disable with --disable-pager. This option is disabled by default.

-p, --password[=name]

Password to use when connecting to 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, mariadb prompts for one. Specifying a password on the command line should be considered insecure. You can use an option file to avoid giving the password on the command line.

--plugin-dir=name

Directory for client-side plugins.

-P, --port=num

Port number to use for connection or 0 for default to, in order of preference, my.cnf, $MYSQL_TCP_PORT, /etc/services, built-in default (3306).

--print-defaults

Print the program argument list and exit. Must be given as the first option.

--progress-reports

Get progress reports for long running commands (such as ALTER TABLE). (Defaults to on; use --skip-progress-reports to disable.)

--prompt=name

Set the mariadb prompt to this value. See prompt command for options.

--protocol=name

The protocol to use for connection (tcp, socket, pipe, memory).

-q, --quick

Don't cache result, print it row by row. This may slow down the server if the output is suspended. Doesn't use history file.

-r, --raw

For tabular output, the “boxing” around columns enables one column value to be distinguished from another. For nontabular output (such as is produced in batch mode or when the --batch or --silent option is given), special characters are escaped in the output so they can be identified easily. Newline, tab, NUL, and backslash are written as \n, \t, \0, and
. The --raw option disables this character escaping.

--reconnect

Reconnect if the connection is lost. This option is enabled by default. Disable with --disable-reconnect or skip-reconnect.

-U, --safe-updates

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 using the --safe-updates option for more.

--secure-auth

Refuse client connecting to server if it uses old (pre-MySQL4.1.1) protocol. Defaults to false.

--select-limit=num

Automatic limit for SELECT when using --safe-updates. Default 1000.

--server-arg=name

Send embedded server this as a parameter.

--shared-memory-base-name=name

Shared-memory name to use for Windows connections using shared memory to a local server (started with the --shared-memory option). Case-sensitive.

--show-warnings

Show warnings after every statement. Applies to interactive and batch mode.

--sigint-ignore

Ignore SIGINT signals (usually CTRL-C).

-s, --silent

Be more silent. This option can be given multiple times to produce less and less output. This option results in nontabular output format and escaping of special characters. Escaping may be disabled by using raw mode; see the description for the --raw option.

--skip-auto-rehash

Disable automatic rehashing. See --auto-rehash.

-N, --skip-column-names

Don't write column names in results. See --column-names.

--skip-comments

Discard comments. Set by default, see --comments to enable.

-L, --skip-line-numbers

Don't write line number for errors. See --line-numbers.

--skip-progress-reports

Disables getting progress reports for long running commands. See --progress-reports.

--skip-reconnect

Don't reconnect if the connection is lost. See --reconnect.

-S, --socket=name

For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.

--ssl

Enables TLS. TLS is also enabled even without setting this option when certain other TLS options are set. The --ssl option does not enable verifying the server certificate by default. In order to verify the server certificate, the user must specify the --ssl-verify-server-cert option. Set by default from MariaDB 10.10.

--ssl-ca=name

Defines a path to a PEM file that should contain one or more X509 certificates for trusted Certificate Authorities (CAs) to use for TLS. This option requires that you use the absolute path, not a relative path. See Secure Connections Overview: Certificate Authorities (CAs) for more information. This option implies the --ssl option.

--ssl-capath=name

Defines a path to a directory that contains one or more PEM files that should each contain one X509 certificate for a trusted Certificate Authority (CA) to use for TLS. This option requires that you use the absolute path, not a relative path. The directory specified by this option needs to be run through the openssl rehash command. See Secure Connections Overview: Certificate Authorities (CAs) for more information. This option is only supported if the client was built with OpenSSL or yaSSL. If the client was built with GnuTLS or Schannel, then this option is not supported. See TLS and Cryptography Libraries Used by MariaDB for more information about which libraries are used on which platforms. This option implies the --ssl option.

--ssl-cert=name

Defines a path to the X509 certificate file to use for TLS. This option requires that you use the absolute path, not a relative path. This option implies the --ssl option.

--ssl-cipher=name

List of permitted ciphers or cipher suites to use for TLS. This option implies the --ssl option.

--ssl-crl=name

Defines a path to a PEM file that should contain one or more revoked X509 certificates to use for TLS. This option requires that you use the absolute path, not a relative path. See Secure Connections Overview: Certificate Revocation Lists (CRLs) for more information. This option is only supported if the client was built with OpenSSL or Schannel. If the client was built with yaSSL or GnuTLS, then this option is not supported. See TLS and Cryptography Libraries Used by MariaDB for more information about which libraries are used on which platforms.

--ssl-crlpath=name

Defines a path to a directory that contains one or more PEM files that should each contain one revoked X509 certificate to use for TLS. This option requires that you use the absolute path, not a relative path. The directory specified by this option needs to be run through the openssl rehash command. See Secure Connections Overview: Certificate Revocation Lists (CRLs) for more information. This option is only supported if the client was built with OpenSSL. If the client was built with yaSSL, GnuTLS, or Schannel, then this option is not supported. See TLS and Cryptography Libraries Used by MariaDB for more information about which libraries are used on which platforms.

--ssl-key=name

Defines a path to a private key file to use for TLS. This option requires that you use the absolute path, not a relative path. This option implies the --ssl option.

--ssl-verify-server-cert

Enables server certificate verification. Prior to MariaDB 11.3, this option is disabled by default, otherwise enabled. Use --disable-ssl or --disable-ssl-verify-server-cert to revert to the pre-11.3 behavior.

-t, --table

Display output in table format. This is the default for interactive use, but can be used to produce table output in batch mode.

--tee=name

Append everything into outfile. See interactive help (\h) also. Does not work in batch mode. Disable with --disable-tee. This option is disabled by default.

--tls-version=name

This option accepts a comma-separated list of TLS protocol versions. A TLS protocol version will only be enabled if it is present in this list. All other TLS protocol versions will not be permitted. See Secure Connections Overview: TLS Protocol Versions for more information. This option was added in MariaDB 10.4.6.

--tls-fp=name

Server certificate fingerprint (implies --ssl). Added in MariaDB 11.3.0.

--tls-fplist=name

File with accepted server certificate fingerprints, one per line (implies --ssl). Added in MariaDB 11.3.0.

-n, --unbuffered

Flush buffer after each query.

-u, --user=name

User for login if not current user.

-v, --verbose

Write more. (-v -v -v gives the table output format).

-V, --version

Output version information and exit.

-E, --vertical

Print the output of a query (rows) vertically. Use the \G delimiter to apply to a particular statement if this option is not enabled.

-w, --wait

If the connection cannot be established, wait and retry instead of aborting.

-X, --xml

Produce XML output. See the mariadb-dump --xml option for more.

Option Files

In addition to reading options from the command-line, mariadb can also read options from option files. If an unknown option is provided to mariadb in an option file, then it is ignored.

The following options relate to how MariaDB command-line tools handles option files. They must be given as the first argument on the command-line:

OptionDescription
--print-defaultsPrint the program argument list and exit.
--no-defaultsDon't read default options from any option file.
--defaults-file=# Only read default options from the given file #.
--defaults-extra-file=# Read this file after the global files are read.
--defaults-group-suffix=# In addition to the default option groups, also read option groups with this suffix.

mariadb is linked with MariaDB Connector/C. However, MariaDB Connector/C does not yet handle the parsing of option files for this client. That is still performed by the server option file parsing code. See MDEV-19035 for more information.

Option Groups

mariadb reads options from the following option groups from option files:

GroupDescription
[mysql] Options read by mysql, which includes both MariaDB Server and MySQL Server.
[mariadb-client]Options read by mariadb. Available starting with MariaDB 10.4.6.
[client] Options read by all MariaDB and MySQL client programs, which includes both MariaDB and MySQL clients. For example, mysqldump.
[client-server]Options read by all MariaDB client programs and the MariaDB Server. This is useful for options like socket and port, which is common between the server and the clients.
[client-mariadb]Options read by all MariaDB client programs.

How to Specify Which Protocol to Use When Connecting to the Server

You can force which protocol to be used to connect to the mariadbd server by giving the protocol option one of the following values: tcp, socket, pipe or memory.

If protocol is not specified, before MariaDB 10.6.1, command line connection properties that do not force protocol are ignored.

From MariaDB 10.6.1, a connection property specified via the command line (e.g. --port=3306) will force its type. The protocol that matches the respective connection property is used, e.g. a TCP/IP connection is created when --port is specified.

If multiple or no connection properties are specified via the command-line, then the following happens:

Linux/Unix

  • If hostname is not specified or hostname is localhost, then Unix sockets are used.
  • In other cases (hostname is given and it's not localhost) then a TCP/IP connection through the port option is used.

Note that localhost is a special value. Using 127.0.0.1 is not the same thing. The latter will connect to the mariadbd server through TCP/IP.

Windows

  • If shared-memory-base-name is specified and hostname is not specified or hostname is localhost, then the connection will happen through shared memory.
  • If shared-memory-base-name is not specified and hostname is not specified or hostname is localhost, then the connection will happen through windows named pipes.
  • Named pipes will also be used if the libmysql / libmariadb client library detects that the client doesn't support TCP/IP.
  • In other cases then a TCP/IP connection through the port option is used.

How to Test Which Protocol is Used

The status command shows you information about which protocol is used:

shell> mariadb test

Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 10
Server version: 10.2.2-MariaDB-valgrind-max-debug Source distribution

Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [test]> status;
--------------
mysql  Ver 15.1 Distrib 10.0.25-MariaDB, for Linux (x86_64) using readline 5.2

Connection id:          10
Current database:       test
Current user:           monty@localhost
...
Connection:             Localhost via UNIX socket
...
UNIX socket:            /tmp/mysql-dbug.sock

mariadb Commands

There are also a number of commands that can be run inside the client. Note that all text commands must be first on line and end with ';'

CommandDescription
?, \?Synonym for `help'.
clear, \cClear the current input statement.
connect, \rReconnect to the server. Optional arguments are db and host.
delimiter, \dSet statement delimiter.
edit, \eEdit command with $EDITOR.
ego, \GSend command to mariadb server, display result vertically.
exit, \qExit mariadb. Same as quit.
go, \gSend command to mariadb server.
help, \hDisplay this help.
nopager, \nDisable pager, print to stdout.
notee, \tDon't write into outfile.
pager, \PSet PAGER [to_pager]. Print the query results via PAGER.
print, \pPrint current command.
prompt, \RChange your mariadb prompt. See prompt command for options.
quit, \qQuit mariadb.
rehash, \# Rebuild completion hash.
source, \.Execute an SQL script file. Takes a file name as an argument.
status, \sGet status information from the server.
system, \!Execute a system shell command. Only works in Unix-like systems.
tee, \TSet outfile [to_outfile]. Append everything into given outfile.
use, \uUse another database. Takes database name as argument.
charset, \CSwitch to another charset. Might be needed for processing binlog with multi-byte charsets.
warnings, \WShow warnings after every statement.
nowarning, \wDon't show warnings after every statement.

The mysql_history File

On Unix, the mariadb client writes a record of executed statements to a history file. By default, this 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.

The .mysql_history file should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords.

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.

prompt Command

The prompt command reconfigures the default prompt \N [\d]>. The string for defining the prompt can contain the following special sequences.

OptionDescription
\cA counter that increments for each statement you issue.
\DThe full current date.
\dThe default database.
\hThe server host.
\lThe current delimiter.
\mMinutes of the current time.
\nA newline character.
\OThe current month in three-letter format (Jan, Feb, ...).
\oThe current month in numeric format.
\Pam/pm.
\pThe current TCP/IP port or socket file.
\RThe current time, in 24-hour military time (0–23).
\rThe current time, standard 12-hour time (1–12).
\SSemicolon.
\sSeconds of the current time.
\tA tab character.
\UYour full user_name@host_name account name.
\uYour user name.
\vThe server version.
\wThe current day of the week in three-letter format (Mon, Tue, ...).
\YThe current year, four digits.
\yThe current year, two digits.
\_A space.
\A space (a space follows the backslash).
\'Single quote.
\"Double quote.
\ \A literal “\” backslash character.
\xx, for any “x” not listed above.

mariadb Tips

This section describes some techniques that can help you use mariadb more effectively.

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:

mariadb> 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)

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, mariadb issues the following statement when it connects to the MariaDB server:

SET sql_safe_updates=1, sql_select_limit=1000, sql_max_join_size=1000000;

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 largeSELECT 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:

mariadb --safe-updates --select_limit=500 --max_join_size=10000

Disabling mariadb Auto-Reconnect

If the mariadb client loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even if mariadb 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 between the first and second statements without you knowing it:

mariadb> SET @a=1;
Query OK, 0 rows affected (0.05 sec)
mariadb> 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)
mariadb> SELECT * FROM t;
+------+
| a    |
+------+
| NULL |
+------+

The @a user variable has been lost with the connection, and after the reconnection it is undefined. If it is important to have mariadb terminate with an error if the connection has been lost, you can start the mariadb client with the --skip-reconnect option.

See Also

Comments

Comments loading...
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.