From 0d90dc16f87bd991d7eb9f536ca46acef7586d95 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Mon, 14 Feb 2011 23:17:35 -0500 Subject: Avoid a few more SET DATA TYPE table rewrites. When the new type is an unconstrained domain over the old type, we don't need to rewrite the table. Noah Misch and Robert Haas --- doc/src/sgml/ref/alter_table.sgml | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'doc/src') diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml index 7e6e72f008e..b8c4c507a2c 100644 --- a/doc/src/sgml/ref/alter_table.sgml +++ b/doc/src/sgml/ref/alter_table.sgml @@ -766,13 +766,14 @@ ALTER TABLE name Adding a column with a non-null default or changing the type of an existing column will require the entire table and indexes to be rewritten. - As an exception, if the old type type is binary coercible to the new - type and the USING clause does not change the column contents, - a table rewrite is not needed, but any indexes on the affected columns - must still be rebuilt. Adding or removing a system oid column - also requires rewriting the entire table. Table and/or index rebuilds may - take a significant amount of time for a large table; and will temporarily - require as much as double the disk space. + As an exception, if the USING clause does not change the column + contents and the old type is either binary coercible to the new type or + an unconstrained domain over the new type, a table rewrite is not needed, + but any indexes on the affected columns must still be rebuilt. Adding or + removing a system oid column also requires rewriting the entire + table. Table and/or index rebuilds may take a significant amount of time + for a large table; and will temporarily require as much as double the disk + space. -- cgit v1.2.3