START TRANSACTION — start a transaction block
START TRANSACTION [transaction_mode[, ...] ] wheretransaction_modeis one of: ISOLATION LEVEL { SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED } READ WRITE | READ ONLY [ NOT ] DEFERRABLE
This command begins a new transaction block. If the isolation level,
read/write mode, or deferrable mode is specified, the new transaction has those
characteristics, as if SET TRANSACTION was executed. This is the same
as the BEGIN command.
Refer to SET TRANSACTION for information on the meaning of the parameters to this statement.
In the standard, it is not necessary to issue START TRANSACTION
to start a transaction block: any SQL command implicitly begins a block.
PostgreSQL's behavior can be seen as implicitly
issuing a COMMIT after each command that does not
follow START TRANSACTION (or BEGIN),
and it is therefore often called “autocommit”.
Other relational database systems might offer an autocommit feature
as a convenience.
The DEFERRABLE
transaction_mode
is a PostgreSQL language extension.
The SQL standard requires commas between successive transaction_modes, but for historical
reasons PostgreSQL allows the commas to be
omitted.
See also the compatibility section of SET TRANSACTION.