On 09/11/14 23:36, Petr Jelinek wrote:
On 09/11/14 23:04, Tom Lane wrote:
I suspect this is actually a bug in the dependency search logic in DROP.
Don't have the energy to chase it right now though.
Yes that's where I started searching also and yes it is. The actual
situation is that the columns of the table that is about to be dropped
are normally not added to the object list that is used for dependency
checks (if the table is going to be dropped who cares about what column
depends on anyway).
But this logic depends on the fact that the columns that belong to that
table are processed after the table was already processed, however as
the new type was added after the table was added, it's processed before
the table and because of the dependency between type and columns, the
columns are also processed before the table and so they are added to the
object list for further dependency checking.
See use and source of object_address_present_add_flags in dependency.c.
So here is what I came up with to fix this. It's quite simple and works
well enough, we don't really have any regression test that would hit
this though.
I wonder if the object_address_present_add_flags should be renamed since
it does bit more than what name suggests at this point.
And I think this should be backpatched to all the versions with
extension support.
--
Petr Jelinek http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index 256486c..e7ec7e2 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -2142,6 +2142,31 @@ object_address_present_add_flags(const ObjectAddress *object,
*/
return true;
}
+ if (object->objectSubId == 0)
+ {
+ /*
+ * If we got here, it means that we are dropping table whose
+ * columns are already in the object list, since we assume
+ * later on that there are no subobjects of object present
+ * in the list, we should remove those.
+ *
+ * Note that this is very rare occasion that normally happens
+ * only when dropping extension which had some of its table
+ * columns ALTERed after CREATE with custom types or
+ * collations.
+ */
+ if (i < addrs->numrefs - 1)
+ {
+ ObjectAddressExtra *thisextra = addrs->extras + i;
+
+ memmove(thisobj, thisobj + 1,
+ (addrs->numrefs - 1 - i) * sizeof(ObjectAddress));
+ memmove(thisextra, thisextra + 1,
+ (addrs->numrefs - 1 - i) * sizeof(ObjectAddressExtra));
+ }
+ addrs->numrefs--;
+ continue;
+ }
}
}
--
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