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Diffstat (limited to 'doc/src/sgml/ddl.sgml')
| -rw-r--r-- | doc/src/sgml/ddl.sgml | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml index 51e90228b22..f8f449ce4bd 100644 --- a/doc/src/sgml/ddl.sgml +++ b/doc/src/sgml/ddl.sgml @@ -3963,6 +3963,11 @@ ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02 </para> <para> + The <command>ATTACH PARTITION</command> command requires taking a + <literal>SHARE UPDATE EXCLUSIVE</literal> lock on the partitioned table. + </para> + + <para> Before running the <command>ATTACH PARTITION</command> command, it is recommended to create a <literal>CHECK</literal> constraint on the table to be attached that matches the expected partition constraint, as @@ -3970,10 +3975,27 @@ ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02 which is otherwise needed to validate the implicit partition constraint. Without the <literal>CHECK</literal> constraint, the table will be scanned to validate the partition constraint while - holding both an <literal>ACCESS EXCLUSIVE</literal> lock on that partition - and a <literal>SHARE UPDATE EXCLUSIVE</literal> lock on the parent table. + holding an <literal>ACCESS EXCLUSIVE</literal> lock on that partition. It is recommended to drop the now-redundant <literal>CHECK</literal> - constraint after <command>ATTACH PARTITION</command> is finished. + constraint after the <command>ATTACH PARTITION</command> is complete. If + the table being attached is itself a partitioned table then each of its + sub-partitions will be recursively locked and scanned until either a + suitable <literal>CHECK</literal> constraint is encountered or the leaf + partitions are reached. + </para> + + <para> + Similarly, if the partitioned table has a <literal>DEFAULT</literal> + partition, it is recommended to create a <literal>CHECK</literal> + constraint which excludes the to-be-attached partition's constraint. If + this is not done then the <literal>DEFAULT</literal> partition will be + scanned to verify that it contains no records which should be located in + the partition being attached. This operation will be performed whilst + holding an <literal>ACCESS EXCLUSIVE</literal> lock on the <literal> + DEFAULT</literal> partition. If the <literal>DEFAULT</literal> partition + is itself a partitioned table then each of its partitions will be + recursively checked in the same way as the table being attached, as + mentioned above. </para> <para> |