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Using transactions
=================
.. toctree::
:maxdepth: 2
start_transaction
commit
rollback
savepoints
Drizzle is a transactional database by default and by design. It collects operations that form tasks and stores them as a single operation, or if that operation is not possible it removes all changes attempted. Transactions are controlled via START TRANSACTION, ROLLBACK, and COMMIT. Savepoints are implemented to allow for a low leverl of granulairty.
A COMMIT statement ends a transaction within Drizzle and makes all changes visible to other users. The order of events is typically to issue a START TRANSACTION statement, execute one or more SQL statements, and then issue a COMMIT statement. Alternatively, a ROLLBACK statement can be issued, which undoes all the work performed since START TRANSACTION was issued. A COMMIT statement will also release any existing savepoints that may be in use.
Drizzle can operate in an autocommit mode, where each statement is committed, via:
SET AUTOCOMMIT= 1
Currently DDL operations are performed as a single transaction, this limitation will be lifted in the future.
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