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Further corrections and improvements to partitioning documentation.

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Amit Langote

Discussion: http://postgr.es/m/80f6b049-e882-f6c3-f82c-f44baa94d369@lab.ntt.co.jp
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Robert Haas 2017-04-03 23:10:16 -04:00
parent c8b5c3cb06
commit 334bf9c77d
1 changed files with 12 additions and 11 deletions
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doc/src/sgml/ddl.sgml
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@ -2932,7 +2932,7 @@ VALUES ('Albany', NULL, NULL, 'NY');
tables and partitions. For example, a partition cannot have any parents tables and partitions. For example, a partition cannot have any parents
other than the partitioned table it is a partition of, nor can a regular other than the partitioned table it is a partition of, nor can a regular
table inherit from a partitioned table making the latter its parent. table inherit from a partitioned table making the latter its parent.
That means partitioned table and partitions do not participate in That means partitioned tables and partitions do not participate in
inheritance with regular tables. Since a partition hierarchy consisting inheritance with regular tables. Since a partition hierarchy consisting
of the partitioned table and its partitions is still an inheritance of the partitioned table and its partitions is still an inheritance
hierarchy, all the normal rules of inheritance apply as described in hierarchy, all the normal rules of inheritance apply as described in
@ -3036,11 +3036,12 @@ CREATE TABLE measurement (
<para> <para>
You may decide to use multiple columns in the partition key for range You may decide to use multiple columns in the partition key for range
partitioning, if desired. Of course, this will often result in a larger partitioning, if desired. Of course, this will often result in a larger
number of partitions, each of which is individually smaller. number of partitions, each of which is individually smaller. On the
criteria. Using fewer columns may lead to coarser-grained other hand, using fewer columns may lead to a coarser-grained
A query accessing the partitioned table will have partitioning criteria with smaller number of partitions. A query
to scan fewer partitions if the conditions involve some or all of these accessing the partitioned table will have to scan fewer partitions if
columns. For example, consider a table range partitioned using columns the conditions involve some or all of these columns.
For example, consider a table range partitioned using columns
<structfield>lastname</> and <structfield>firstname</> (in that order) <structfield>lastname</> and <structfield>firstname</> (in that order)
as the partition key. as the partition key.
</para> </para>
@ -3167,8 +3168,8 @@ CREATE INDEX ON measurement_y2008m01 (logdate);
</para> </para>
<para> <para>
The simplest option for removing old data is simply to drop the partition The simplest option for removing old data is to drop the partition that
that is no longer necessary: is no longer necessary:
<programlisting> <programlisting>
DROP TABLE measurement_y2006m02; DROP TABLE measurement_y2006m02;
</programlisting> </programlisting>
@ -3595,8 +3596,8 @@ DO INSTEAD
<sect3 id="ddl-partitioning-inheritance-maintenance"> <sect3 id="ddl-partitioning-inheritance-maintenance">
<title>Partition Maintenance</title> <title>Partition Maintenance</title>
<para> <para>
To remove old data quickly, simply to drop the partition that is no To remove old data quickly, simply drop the partition that is no longer
longer necessary: necessary:
<programlisting> <programlisting>
DROP TABLE measurement_y2006m02; DROP TABLE measurement_y2006m02;
</programlisting> </programlisting>
@ -3692,7 +3693,7 @@ ANALYZE measurement;
Triggers or rules will be needed to route rows to the desired Triggers or rules will be needed to route rows to the desired
partition, unless the application is explicitly aware of the partition, unless the application is explicitly aware of the
partitioning scheme. Triggers may be complicated to write, and will partitioning scheme. Triggers may be complicated to write, and will
be much slower than the tuple routing performed interally by be much slower than the tuple routing performed internally by
declarative partitioning. declarative partitioning.
</para> </para>
</listitem> </listitem>