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| -rw-r--r-- | doc/src/sgml/ref/create_index.sgml | 12 |
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. |