doc: clarify PERIOD and WITHOUT OVERLAPS in CREATE TABLE

Discussion: https://postgr.es/m/04938501-fc8f-46f3-97a4-9a81a3f24530@illuminatedcomputing.com

Author: Paul Jungwirth

Backpatch-through: master

diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index 02f31d2d6fd72799cc53f2165f6ff6dba18e65a0..75f06bc49cc35482ca24d73d5edec573e1cb5f69 100644 (file)
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -1184,11 +1184,13 @@ WITH ( MODULUS numeric_literal, REM
       referent for its entire duration.  This column must be a range or
       multirange type.  In addition, the referenced table must have a primary
       key or unique constraint declared with WITHOUT
-      OVERLAPS.  Finally, if one side of the foreign key uses
-      PERIOD, the other side must too.  If the 
-      class="parameter">refcolumn list is omitted, the
-      WITHOUT OVERLAPS part of the primary key is treated
-      as if marked with PERIOD.
+      OVERLAPS. Finally, if the foreign key has a PERIOD
+      column_name specification
+      the corresponding refcolumn,
+      if present, must also be marked PERIOD.  If the
+      refcolumn clause is omitted,
+      and thus the reftable's primary key constraint chosen, the primary key
+      must have its final column marked WITHOUT OVERLAPS.