diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml index f53e3c6bec1071d46065dbcd9ee7f631cde263eb..39382e99c753ebef5ec077483383fce19735b246 100644 --- a/doc/src/sgml/ddl.sgml +++ b/doc/src/sgml/ddl.sgml @@ -3331,6 +3331,44 @@ ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02 One may then drop the constraint after <command>ATTACH PARTITION</command> is finished, because it is no longer necessary. </para> + + <para> + As explained above, it is possible to create indexes on partitioned tables + and they are applied automatically to the entire hierarchy. This is very + convenient, as not only the existing partitions will become indexed, but + also any partitions that are created in the future will. One limitation is + that it's not possible to use the <literal>CONCURRENTLY</literal> + qualifier when creating such a partitioned index. To overcome long lock + times, it is possible to use <command>CREATE INDEX ON ONLY</command> + the partitioned table; such an index is marked invalid, and the partitions + do not get the index applied automatically. The indexes on partitions can + be created separately using <literal>CONCURRENTLY</literal>, and later + <firstterm>attached</firstterm> to the index on the parent using + <command>ALTER INDEX .. ATTACH PARTITION</command>. Once indexes for all + partitions are attached to the parent index, the parent index is marked + valid automatically. Example: +<programlisting> +CREATE INDEX measurement_usls_idx ON ONLY measurement (unitsales); + +CREATE INDEX measurement_usls_200602_idx + ON measurement_y2006m02 (unitsales); +ALTER INDEX measurement_usls_idx + ATTACH PARTITION measurement_usls_200602_idx; +... +</programlisting> + + This technique can be used with <literal>UNIQUE</literal> and + <literal>PRIMARY KEY</literal> constraints too; the indexes are created + implicitly when the constraint is created. Example: +<programlisting> +ALTER TABLE ONLY measurement ADD UNIQUE (city_id, logdate); + +ALTER TABLE measurement_y2006m02 ADD UNIQUE (city_id, logdate); +ALTER INDEX measurement_city_id_logdate_key + ATTACH PARTITION measurement_y2006m02_city_id_logdate_key; +... +</programlisting> + </para> </sect3> <sect3 id="ddl-partitioning-declarative-limitations">