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BEGIN(5)
NAME
  BEGIN - start a transaction block

SYNOPSIS
  BEGIN [ WORK | TRANSACTION ]

DESCRIPTION
  BEGIN initiates a transaction block, that is, all statements after BEGIN
  command will be executed in a single transaction until an explicit COMMIT
  [commit(5)] or ROLLBACK [rollback(l)] is given.  By default (without
  BEGIN), PostgreSQL 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.

PARAMETERS
  WORK

  TRANSACTION
       Optional key words. They have no effect.

NOTES
  START TRANSACTION [start_transaction(5)] has the same functionality as
  BEGIN.

  Use COMMIT [commit(5)] or ROLLBACK [rollback(5)] 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.

EXAMPLES
  To begin a transaction block:

  BEGIN;

COMPATIBILITY
  BEGIN is a PostgreSQL language extension. There is no explicit BEGIN
  command in the SQL standard; transaction initiation is always implicit and
  it terminates either with a COMMIT or ROLLBACK statement.

  Other relational database systems may offer an autocommit feature as a
  convenience.

  Incidentally, the BEGIN key word is used for a different purpose in
  embedded SQL. You are advised to be careful about the transaction semantics
  when porting database applications.

SEE ALSO
  COMMIT [commit(5)], ROLLBACK [rollback(l)]

Index for Section 5

Alphabetical listing for B

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