463 MVCC and transaction id

   463 MVCC and transaction id

   464 =======================

   464 =======================

   465 

   465 

   466 As being MVCC Postgres doesn't delete or update existing rows. Row visibility is controled by

   466 As being MVCC Postgres doesn't delete or update existing rows. Row visibility is controled by

   467 transaction id (monotonous incremented number): ``xmin`` - first transaction that can see row,

   467 transaction id (monotonous incremented number): ``xmin`` - first transaction that can see row,

   469 

   469 

   470   SELECT xmin, xmax, * FROM foo WHERE id < 5 ORDER BY id;

   470   SELECT xmin, xmax, * FROM foo WHERE id < 5 ORDER BY id;

   471 

   471 

   472 Vacuum

   472 Vacuum

   473 ======

   473 ======