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14.5.3. BDB Startup Options

The following options to mysqld can be used to change the behavior of the BDB storage engine. For more information, see Section 5.2.1, “mysqld Command Options”.

  • --bdb-data-direct

    Turn off system buffering of BDB database files to avoid double caching. This option was added in MySQL 5.1.4.

  • --bdb-home=path

    The base directory for BDB tables. This should be the same directory that you use for --datadir.

  • --bdb-lock-detect=method

    The BDB lock detection method. The option value should be DEFAULT, OLDEST, RANDOM, YOUNGEST, MAXLOCKS, MINLOCKS, MAXWRITE, or MINWRITE.

  • --bdb-log-direct

    Turn off system buffering of BDB log files to avoid double caching. This option was added in MySQL 5.1.4.

  • --bdb-logdir=file_name

    The BDB log file directory.

  • --bdb-no-recover

    Do not start Berkeley DB in recover mode.

  • --bdb-no-sync

    Don't synchronously flush the BDB logs. This option is deprecated; use --skip-sync-bdb-logs instead (see the description for --sync-bdb-logs).

  • --bdb-shared-data

    Start Berkeley DB in multi-process mode. (Do not use DB_PRIVATE when initializing Berkeley DB.)

  • --bdb-tmpdir=path

    The BDB temporary file directory.

  • --skip-bdb

    Disable the BDB storage engine.

  • --sync-bdb-logs

    Synchronously flush the BDB logs. This option is enabled by default. Use --skip-sync-bdb-logs to disable it.

If you use the --skip-bdb option, MySQL does not initialize the Berkeley DB library and this saves a lot of memory. However, if you use this option, you cannot use BDB tables. If you try to create a BDB table, MySQL uses the default storage engine instead.

Normally, you should start mysqld without the --bdb-no-recover option if you intend to use BDB tables. However, this may cause problems when you try to start mysqld if the BDB log files are corrupted. See Section 2.9.2.3, “Starting and Troubleshooting the MySQL Server”.

With the bdb_max_lock variable, you can specify the maximum number of locks that can be active on a BDB table. The default is 10,000. You should increase this if errors such as the following occur when you perform long transactions or when mysqld has to examine many rows to execute a query:

bdb: Lock table is out of available locks
Got error 12 from ...

You may also want to change the binlog_cache_size and max_binlog_cache_size variables if you are using large multiple-statement transactions. See Section 5.11.4, “The Binary Log”.

See also Section 5.2.2, “Server System Variables”.


 
 
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