7.6.7 Restrictions on BDB Tables

Here follows the restrictions you have when using BDB tables:

• BDB tables store in the `.db' file the path to the file as it was created. (This was done to be able to detect locks in a multi-user environment that supports symlinks). The effect of this is that BDB tables are not movable between directories!
• When taking backups of BDB tables, you have to either use mysqldump or take a backup of all table_name.db files and the BDB log files. The BDB log files are the files in the base data directory named log.XXXXXXXXXX (ten digits); The BDB storage engine stores unfinished transactions in the log files and requires these logs to be present when mysqld starts.

User Comments

Unique keys do not support multiple nulls for
secondary keys on BDB tables.
create table test (
id int unsigned not null primary key,
id2 int unsigned unique)
type=BDB;
insert into test set id=1;
insert into test set id=2;
"Duplicate entry 'Null' for key 2"

InnoDB and MyISAM tables will accept the second
insert.

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