MySQL Manual
7 MySQL Table Types
7.6.3 BDB startup options
If you are running with AUTOCOMMIT=0 then your changes in BDB
tables will not be updated until you execute COMMIT. Instead of commit
you can execute ROLLBACK to forget your changes. See section 6.7.1 START TRANSACTION, COMMIT, and ROLLBACK Syntax.
If you are running with AUTOCOMMIT=1 (the default), your changes
will be committed immediately. You can start an extended transaction with
the BEGIN WORK SQL command, after which your changes will not be
committed until you execute COMMIT (or decide to ROLLBACK
the changes).
The following options to mysqld can be used to change the behaviour of
BDB tables:
| Option | Description |
--bdb-home=directory | Base directory for BDB tables. This should be the same directory you use for --datadir.
|
--bdb-lock-detect=# | Berkeley lock detect. One of (DEFAULT, OLDEST, RANDOM, or YOUNGEST).
|
--bdb-logdir=directory | Berkeley DB log file directory. |
--bdb-no-sync | Don't synchronously flush logs. |
--bdb-no-recover | Don't start Berkeley DB in recover mode. |
--bdb-shared-data | Start Berkeley DB in multi-process mode (Don't use DB_PRIVATE when initialising Berkeley DB)
|
--bdb-tmpdir=directory | Berkeley DB temporary file directory. |
--skip-bdb | Disable usage of BDB tables.
|
-O bdb_max_lock=1000 | Set the maximum number of locks possible. See section 4.5.7.4 SHOW VARIABLES.
|
If you use --skip-bdb, MySQL will not initialise the
Berkeley DB library and this will save a lot of memory. Of course,
you cannot use BDB tables if you are using this option. If you try
to create a BDB table, MySQL will instead create a MyISAM table.
Normally you should start mysqld without --bdb-no-recover if you
intend to use BDB tables. This may, however, give you problems when you
try to start mysqld if the BDB log files are corrupted. See section 2.4.2 Problems Starting the MySQL Server.
With bdb_max_lock you can specify the maximum number of locks
(10000 by default) you can have active on a BDB table. You should
increase this if you get errors of type bdb: Lock table is out of
available locks or Got error 12 from ... when you have do long
transactions or when mysqld has to examine a lot of rows to
calculate the query.
You may also want to change binlog_cache_size and
max_binlog_cache_size if you are using big multi-line transactions.
See section 6.7.1 START TRANSACTION, COMMIT, and ROLLBACK Syntax.
