mirror/postgresql
2
0
Fork 0
mirror of https://git.postgresql.org/git/postgresql.git synced 2024-12-27 08:39:28 +08:00
Code Issues Packages Projects Releases Wiki Activity

Clarify hash index caution and copy to CREATE INDEX docs

Browse Source
This commit is contained in:
Simon Riggs 2012-10-17 08:14:29 +01:00
parent 22cc3b35f4
commit 9f9695a0cd
2 changed files with 16 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
doc/src/sgml/indices.sgml
View File

@ -196,8 +196,10 @@ CREATE INDEX <replaceable>name</replaceable> ON <replaceable>table</replaceable>
<para>
Hash index operations are not presently WAL-logged,
so hash indexes might need to be rebuilt with <command>REINDEX</>
after a database crash. They are also not replicated over streaming or
file-based replication.
after a database crash if there were unwritten changes.
Also, changes to hash indexes are not replicated over streaming or
file-based 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>

12
doc/src/sgml/ref/create_index.sgml
View File

@ -466,6 +466,18 @@ 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 streaming or
file-based 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.