</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>.)

the query conditions use.

</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.