Synopsis
BEGIN [ WORK | TRANSACTION ] [ transaction_mode [, ...] ]
where transaction_mode is one of:
ISOLATION LEVEL { SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED }
READ WRITE | READ ONLY
Description
BEGIN initiates a transaction block, that is,
all statements after a BEGIN command will be
executed in a single transaction until an explicit COMMIT or ROLLBACK is given.
By default (without BEGIN),
EnterpriseDB executes
transactions in "autocommit" mode, that is, each
statement is executed in its own transaction and a commit is
implicitly performed at the end of the statement (if execution was
successful, otherwise a rollback is done).
Statements are executed more quickly in a transaction block, because
transaction start/commit requires significant CPU and disk
activity. Execution of multiple statements inside a transaction is
also useful to ensure consistency when making several related changes:
other sessions will be unable to see the intermediate states
wherein not all the related updates have been done.
If the isolation level or read/write mode is specified, the new
transaction has those characteristics, as if
SET TRANSACTION
was executed.
Notes
START TRANSACTION has the same functionality
as BEGIN.
Use COMMIT or
ROLLBACK
to terminate a transaction block.
Issuing BEGIN when already inside a transaction block will
provoke a warning message. The state of the transaction is not affected.
To nest transactions within a transaction block, use savepoints
(see SAVEPOINT).
For reasons of backwards compatibility, the commas between successive
transaction_modes may be
omitted.