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Add hash index caution to CREATE INDEX docs

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Simon Riggs 2012-10-17 08:35:39 +01:00
parent 6d934e4aae
commit 8ae503a5be
1 changed files with 12 additions and 0 deletions
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doc/src/sgml/ref/create_index.sgml
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@ -428,6 +428,18 @@ Indexes:
they can be useful.
</para>
<caution>
<para>
Hash index operations are not presently WAL-logged,
so hash indexes might need to be rebuilt with <command>REINDEX</>
after a database crash if there were unwritten changes.
Also, changes to hash indexes are not replicated over warm standby
replication after the initial base backup, so they
give wrong anwers to queries that subsequently use them.
For these reasons, hash index use is presently discouraged.
</para>
</caution>
<para>
Currently, only the B-tree, GiST and GIN index methods support
multicolumn indexes. Up to 32 fields can be specified by default.