Tom Lane wrote:
> Bruce Momjian <[email protected]> writes:
> > Tom Lane wrote:
> >> The approach I originally suggested was to create the enum type with
> >> *no* members, and then add the values one at a time.
>
> > Well, I was hesitant to modify the grammar, unless we want the ability
> > to create enums with zero values. Doing enum with only one value will
> > not be too complex for me and I don't think binary upgrade should affect
> > the grammar unless there are other reasons we want to change.
>
> The reason I don't want to do it that way is that then you need two
> ugly kluges in the backend, not just one. With the zero-and-add-one
> approach there is no need to have a "next enum oid" variable at all.
Uh, I still need that variable because that is how we are going to set
the oid in EnumValuesCreate(), unless we want to add dummy oid-value
arguments to that function for use only by the binary upgrade
server-side function. I have actually coded the variable case already
so you can see how it looks; attached. Most of the patch is just
indenting of the existing oid assignment block.
> > We do allow tables with no columns, but we allow the addition of columns
> > to a table, so it makes more sense there.
>
> Well, we might eventually allow addition of values to enums too; the
> fact that it's not implemented outside pg_migrator right now doesn't
> mean we won't ever think of a solution. In any case I'm not persuaded
> that a zero-element enum is totally without value. Think of it like a
> domain with a "must be null" constraint.
OK, but that is going to expand the my patch. I will probably implement
zero-element enums first and then go ahead and do the binary upgrade
part. Zero-element enums will simplify the pg_dump code.
--
Bruce Momjian <[email protected]> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Index: src/backend/catalog/pg_enum.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/catalog/pg_enum.c,v
retrieving revision 1.11
diff -c -c -r1.11 pg_enum.c
*** src/backend/catalog/pg_enum.c 24 Dec 2009 22:17:58 -0000 1.11
--- src/backend/catalog/pg_enum.c 24 Dec 2009 22:29:17 -0000
***************
*** 25,30 ****
--- 25,32 ----
static int oid_cmp(const void *p1, const void *p2);
+ Oid binary_upgrade_next_pg_enum_oid = InvalidOid;
+
/*
* EnumValuesCreate
***************
*** 58,82 ****
tupDesc = pg_enum->rd_att;
/*
! * Allocate oids. While this method does not absolutely guarantee that we
! * generate no duplicate oids (since we haven't entered each oid into the
! * table before allocating the next), trouble could only occur if the oid
! * counter wraps all the way around before we finish. Which seems
! * unlikely.
*/
oids = (Oid *) palloc(num_elems * sizeof(Oid));
! for (elemno = 0; elemno < num_elems; elemno++)
{
/*
! * The pg_enum.oid is stored in user tables. This oid must be
! * preserved by binary upgrades.
*/
! oids[elemno] = GetNewOid(pg_enum);
}
- /* sort them, just in case counter wrapped from high to low */
- qsort(oids, num_elems, sizeof(Oid), oid_cmp);
-
/* and make the entries */
memset(nulls, false, sizeof(nulls));
--- 60,94 ----
tupDesc = pg_enum->rd_att;
/*
! * Allocate oids
*/
oids = (Oid *) palloc(num_elems * sizeof(Oid));
! if (num_elems == 1 && OidIsValid(binary_upgrade_next_pg_enum_oid))
! {
! oids[0] = binary_upgrade_next_pg_enum_oid;
! binary_upgrade_next_pg_enum_oid = InvalidOid;
! }
! else
{
/*
! * While this method does not absolutely guarantee that we generate
! * no duplicate oids (since we haven't entered each oid into the
! * table before allocating the next), trouble could only occur if
! * the oid counter wraps all the way around before we finish. Which
! * seems unlikely.
*/
! for (elemno = 0; elemno < num_elems; elemno++)
! {
! /*
! * The pg_enum.oid is stored in user tables. This oid must be
! * preserved by binary upgrades.
! */
! oids[elemno] = GetNewOid(pg_enum);
! }
! /* sort them, just in case counter wrapped from high to low */
! qsort(oids, num_elems, sizeof(Oid), oid_cmp);
}
/* and make the entries */
memset(nulls, false, sizeof(nulls));
--
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