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START TRANSACTION(7) PostgreSQL 12.1 Documentation START TRANSACTION(7)

START_TRANSACTION - start a transaction block

START TRANSACTION [ transaction_mode [, ...] ]
where transaction_mode is 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 (SET_TRANSACTION(7)) was executed. This is the same as the BEGIN(7) command.

Refer to SET TRANSACTION (SET_TRANSACTION(7)) 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 (SET_TRANSACTION(7)).

BEGIN(7), COMMIT(7), ROLLBACK(7), SAVEPOINT(7), SET TRANSACTION (SET_TRANSACTION(7))
2019 PostgreSQL 12.1