On Thu, Aug 18, 2016 at 5:15 AM, Amit Langote
<langote_amit...@lab.ntt.co.jp> wrote:
> On 2016/07/25 17:18, Amit Langote wrote:
>> The comment seems to have been copied from ATExecAddColumn, which says:
>>
>> /*
>> * If we are told not to recurse, there had better not be any
>> - * child tables; else the addition would put them out of step.
>>
>> For ATExecValidateConstraint, it should say something like:
>>
>> + * child tables; else validating the constraint would put them
>> + * out of step.
>>
>> Attached patch fixes it.
>
> I noticed that the ALTER TABLE documentation doesn't mention that VALIDATE
> CONSTRAINT will fail if ONLY is specified and there are descendant tables.
> It only mentions that a constraint cannot be renamed unless also renamed
> in the descendant tables.
>
> Attached patch fixes that.
I did some wordsmithing on the two patches you posted to this thread.
I suggest the attached version. What do you think?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 6f51cbc..a070041 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -1028,11 +1028,15 @@ ALTER TABLE ALL IN TABLESPACE <replaceable class="PARAMETER">name</replaceable>
<para>
If a table has any descendant tables, it is not permitted to add,
- rename, or change the type of a column, or rename an inherited constraint
- in the parent table without doing
- the same to the descendants. That is, <command>ALTER TABLE ONLY</command>
- will be rejected. This ensures that the descendants always have
- columns matching the parent.
+ rename, or change the type of a column constraint in the parent table
+ without doing same to the descendants. This ensures that the descendants
+ always have columns matching the parent. Similarly, a constraint cannot be
+ renamed in the parent without also renaming it in all descendents, so that
+ constraints also match between the parent and its descendents.
+ Also, because selecting from the parent also selects from its descendents,
+ a constraint on the parent cannot be marked valid unless it is also marked
+ valid for those descendents. In all of these cases, <command>ALTER TABLE
+ ONLY</command> will be rejected.
</para>
<para>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 86e9814..d312762 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -6908,7 +6908,8 @@ ATExecValidateConstraint(Relation rel, char *constrName, bool recurse,
/*
* If we are told not to recurse, there had better not be any
- * child tables; else the addition would put them out of step.
+ * child tables, because we can't mark the constraint on the
+ * parent valid unless it is valid for all child tables.
*/
if (!recurse)
ereport(ERROR,
--
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