## Name

START TRANSACTION — start a transaction block

## Synopsis

    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

## Description

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.

## Parameters

Refer to SET TRANSACTION for information on the meaning of the parameters to this statement.

## Compatibility

In the standard, it is not necessary to issue `START TRANSACTION` to start a transaction block: any SQL command implicitly begins a block. Postgres Pro'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 Postgres Pro language extension.

The SQL standard requires commas between successive `transaction_modes`, but for historical reasons Postgres Pro allows the commas to be omitted.

See also the compatibility section of SET TRANSACTION.

## See Also

BEGIN, COMMIT, ROLLBACK, SAVEPOINT, SET TRANSACTION