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Diffstat (limited to 'docs/ref/databases.txt')
| -rw-r--r-- | docs/ref/databases.txt | 34 |
1 files changed, 9 insertions, 25 deletions
diff --git a/docs/ref/databases.txt b/docs/ref/databases.txt index 821d6e8d1b..e7d474a81d 100644 --- a/docs/ref/databases.txt +++ b/docs/ref/databases.txt @@ -276,7 +276,7 @@ MySQL notes Version support --------------- -Django supports MySQL 5.5 and higher. +Django supports MySQL 5.6 and higher. Django's ``inspectdb`` feature uses the ``information_schema`` database, which contains detailed data on all database schemas. @@ -294,36 +294,20 @@ Storage engines MySQL has several `storage engines`_. You can change the default storage engine in the server configuration. -Until MySQL 5.5.4, the default engine was MyISAM_ [#]_. The main drawbacks of -MyISAM are that it doesn't support transactions or enforce foreign-key -constraints. On the plus side, it was the only engine that supported full-text -indexing and searching until MySQL 5.6.4. +MySQL's default storage engine is InnoDB_. This engine is fully transactional +and supports foreign key references. It's the recommended choice. However, the +InnoDB autoincrement counter is lost on a MySQL restart because it does not +remember the ``AUTO_INCREMENT`` value, instead recreating it as "max(id)+1". +This may result in an inadvertent reuse of :class:`~django.db.models.AutoField` +values. -Since MySQL 5.5.5, the default storage engine is InnoDB_. This engine is fully -transactional and supports foreign key references. It's probably the best -choice at this point. However, note that the InnoDB autoincrement counter -is lost on a MySQL restart because it does not remember the -``AUTO_INCREMENT`` value, instead recreating it as "max(id)+1". This may -result in an inadvertent reuse of :class:`~django.db.models.AutoField` values. - -If you upgrade an existing project to MySQL 5.5.5 and subsequently add some -tables, ensure that your tables are using the same storage engine (i.e. MyISAM -vs. InnoDB). Specifically, if tables that have a ``ForeignKey`` between them -use different storage engines, you may see an error like the following when -running ``migrate``:: - - _mysql_exceptions.OperationalError: ( - 1005, "Can't create table '\\db_name\\.#sql-4a8_ab' (errno: 150)" - ) +The main drawbacks of MyISAM_ are that it doesn't support transactions or +enforce foreign-key constraints. .. _storage engines: https://dev.mysql.com/doc/refman/en/storage-engines.html .. _MyISAM: https://dev.mysql.com/doc/refman/en/myisam-storage-engine.html .. _InnoDB: https://dev.mysql.com/doc/refman/en/innodb-storage-engine.html -.. [#] Unless this was changed by the packager of your MySQL package. We've - had reports that the Windows Community Server installer sets up InnoDB as - the default storage engine, for example. - .. _mysql-db-api-drivers: MySQL DB API Drivers |