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| -rw-r--r-- | doc/src/sgml/indices.sgml | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/doc/src/sgml/indices.sgml b/doc/src/sgml/indices.sgml index 23bbec6eb71..5f72e7d0735 100644 --- a/doc/src/sgml/indices.sgml +++ b/doc/src/sgml/indices.sgml @@ -395,7 +395,8 @@ CREATE INDEX test2_mm_idx ON test2 (major, minor); </para> <para> - Currently, only the B-tree, GiST and GIN index types support multicolumn + Currently, only the B-tree, GiST, GIN, and BRIN + index types support multicolumn indexes. Up to 32 columns can be specified. (This limit can be altered when building <productname>PostgreSQL</productname>; see the file <filename>pg_config_manual.h</filename>.) @@ -441,6 +442,15 @@ CREATE INDEX test2_mm_idx ON test2 (major, minor); </para> <para> + A multicolumn BRIN index can be used with query conditions that + involve any subset of the index's columns. Like GIN and unlike B-tree or + GiST, index search effectiveness is the same regardless of which index + column(s) the query conditions use. The only reason to have multiple BRIN + indexes instead of one multicolumn BRIN index on a single table is to have + a different <literal>pages_per_range</literal> storage parameter. + </para> + + <para> Of course, each column must be used with operators appropriate to the index type; clauses that involve other operators will not be considered. </para> |