diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ref/alter_table.sgml | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml index 5437626c3fe..7ee0aa8ca07 100644 --- a/doc/src/sgml/ref/alter_table.sgml +++ b/doc/src/sgml/ref/alter_table.sgml @@ -324,9 +324,13 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> as <literal>NOT VALID</literal>, by scanning the table to ensure there are no rows for which the constraint is not satisfied. Nothing happens if the constraint is already marked valid. - The value of separating validation from initial creation of the - constraint is that validation requires a lesser lock on the table - than constraint creation does. + </para> + <para> + Validation can be a long process on larger tables and currently requires + an <literal>ACCESS EXCLUSIVE</literal> lock. The value of separating + validation from initial creation is that you can defer validation to less + busy times, or can be used to give additional time to correct pre-existing + errors while preventing new errors. </para> </listitem> </varlistentry> |