diff options
| author | Alexander Korotkov | 2020-06-20 10:34:54 +0000 |
|---|---|---|
| committer | Alexander Korotkov | 2020-06-20 10:34:54 +0000 |
| commit | 15cb2bd27009f73a84a35c2ba60fdd105b4bf263 (patch) | |
| tree | 366bd6095f871106f3c0476420721303663296f9 /doc/src/sgml/btree.sgml | |
| parent | d28ab91e7155353d4377abad5a7d5b0f07450867 (diff) | |
Add documentation for opclass options
911e7020770 added opclass options and adjusted documentation for each
particular affected opclass. However, documentation for extendability was
not adjusted. This commit adjusts documentation for interfaces of index AMs
and opclasses.
Discussion: https://postgr.es/m/CAH2-WzmQnW6%2Bz5F9AW%2BSz%2BzEcEvXofTwh_A9J3%3D_WA-FBP0wYg%40mail.gmail.com
Author: Alexander Korotkov
Reported-by: Peter Geoghegan
Reviewed-by: Peter Geoghegan
Diffstat (limited to 'doc/src/sgml/btree.sgml')
| -rw-r--r-- | doc/src/sgml/btree.sgml | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/doc/src/sgml/btree.sgml b/doc/src/sgml/btree.sgml index 73947db55cb..2c4dd48ea35 100644 --- a/doc/src/sgml/btree.sgml +++ b/doc/src/sgml/btree.sgml @@ -550,6 +550,39 @@ equalimage(<replaceable>opcintype</replaceable> <type>oid</type>) returns bool </para> </listitem> </varlistentry> + <varlistentry> + <term><function>options</function></term> + <listitem> + <para> + Optionally, a B-tree operator family may provide + <function>options</function> (<quote>operator class specific + options</quote>) support functions, registered under support + function number 5. These functions define set of user-visible + parameters that control operator class behavior. + </para> + <para> + An <function>options</function> support function must have the + signature +<synopsis> +options(<replaceable>relopts</replaceable> <type>local_relopts *</type>) returns void +</synopsis> + The function has given pointer to <replaceable>local_relopts</replaceable> + struct, which needs to be filled with a set of operator class + specific options. The options can be accessed from other support + functions using <literal>PG_HAS_OPCLASS_OPTIONS()</literal> and + <literal>PG_GET_OPCLASS_OPTIONS()</literal> macros. + </para> + <para> + Currently, no B-Tree operator class has <function>options</function> + support function. B-tree doesn't allow flexible representation of keys + like GiST, SP-GiST, GIN and BRIN do. So, <function>options</function> + probably doesn't have much usage in current shape of B-tree index + access method. Nevertheless, this support function was added to B-tree + for uniformity, and probably it will found its usage during further + evolution of B-tree in <productname>PostgreSQL</productname>. + </para> + </listitem> + </varlistentry> </variablelist> </sect1> |