diff options
| -rw-r--r-- | doc/src/sgml/indices.sgml | 6 | ||||
| -rw-r--r-- | doc/src/sgml/ref/create_index.sgml | 12 |
2 files changed, 16 insertions, 2 deletions
diff --git a/doc/src/sgml/indices.sgml b/doc/src/sgml/indices.sgml index 2dedb153c06..c7c3211f1f1 100644 --- a/doc/src/sgml/indices.sgml +++ b/doc/src/sgml/indices.sgml @@ -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> diff --git a/doc/src/sgml/ref/create_index.sgml b/doc/src/sgml/ref/create_index.sgml index 5d0ea4372fc..8f266ed6d00 100644 --- a/doc/src/sgml/ref/create_index.sgml +++ b/doc/src/sgml/ref/create_index.sgml @@ -451,6 +451,18 @@ 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. |