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authorSimon Riggs2012-10-17 07:35:39 +0000
committerSimon Riggs2012-10-17 07:35:39 +0000
commit8ae503a5bee27959bcb063785d3dd25cb4966eca (patch)
tree012282972663a2d18c32a67da839231fb328f0ea
parent6d934e4aaec1e7712e088a48d9fc02acc5be4d25 (diff)
Add hash index caution to CREATE INDEX docs
-rw-r--r--doc/src/sgml/ref/create_index.sgml12
1 files changed, 12 insertions, 0 deletions
diff --git a/doc/src/sgml/ref/create_index.sgml b/doc/src/sgml/ref/create_index.sgml
index 5104a656e9e..400450460de 100644
--- a/doc/src/sgml/ref/create_index.sgml
+++ b/doc/src/sgml/ref/create_index.sgml
@@ -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.