From 46a0cd4cefb4d9b462d8cc4df5e7ecdd190bea92 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut
Date: Wed, 24 Jan 2024 15:43:41 +0100
Subject: Add temporal PRIMARY KEY and UNIQUE constraints

Add WITHOUT OVERLAPS clause to PRIMARY KEY and UNIQUE constraints.
These are backed by GiST indexes instead of B-tree indexes, since they
are essentially exclusion constraints with = for the scalar parts of
the key and && for the temporal part.

Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg@mail.gmail.com
---
 doc/src/sgml/gist.sgml | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

(limited to 'doc/src/sgml/gist.sgml')

diff --git a/doc/src/sgml/gist.sgml b/doc/src/sgml/gist.sgml
index 7c20f8467b4..8a19f156d83 100644
--- a/doc/src/sgml/gist.sgml
+++ b/doc/src/sgml/gist.sgml
@@ -298,7 +298,8 @@ CREATE INDEX ON my_table USING GIST (my_inet_column inet_ops);
    The optional twelfth method <function>stratnum</function> is used to
    translate well-known <literal>RT*StrategyNumber</literal>s (from
    <filename>src/include/access/stratnum.h</filename>) into strategy numbers
-   used by the operator class.
+   used by the operator class.  This lets the core code look up operators for
+   temporal constraint indexes.
  </para>
 
  <variablelist>
@@ -1185,6 +1186,17 @@ my_sortsupport(PG_FUNCTION_ARGS)
        operator class has no matching strategy.
       </para>
 
+      <para>
+       This is used for temporal index constraints (i.e., <literal>PRIMARY
+       KEY</literal> and <literal>UNIQUE</literal>).  If the operator class
+       provides this function and it returns results for
+       <literal>RTEqualStrategyNumber</literal>, it can be used in the
+       non-<literal>WITHOUT OVERLAPS</literal> part(s) of an index constraint.
+       If it returns results for <literal>RTOverlapStrategyNumber</literal>,
+       the operator class can be used in the <literal>WITHOUT
+       OVERLAPS</literal> part of an index constraint.
+      </para>
+
       <para>
        The <acronym>SQL</acronym> declaration of the function must look like
        this:
-- 
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