diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ref/alter_table.sgml | 15 |
1 files changed, 8 insertions, 7 deletions
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 <replaceable class="PARAMETER">name</replaceable> <para> 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 <literal>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 <literal>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 <literal>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 <literal>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. </para> <para> |