On 2015/04/28 15:17, Amit Langote wrote:
The code at the beginning of ATSimpleRecursion() looks like -
/*
* Propagate to children if desired. Non-table relations never have
* children, so no need to search in that case.
*/
if (recurse && rel->rd_rel->relkind == RELKIND_RELATION)
Not sure if it's great idea, but now that foreign tables can also have
children, should above be changed to take that into account?
Yeah, I think we should now allow the recursion for inheritance parents
that are foreign tables as well. Attached is a patch for that.
so even foreign inheritance parents expand for
various ALTER TABLE actions like adding a column though that is not a
meaningful operation on foreign tables anyway.
An example,
postgres=# alter foreign table fparent alter a type char;
ALTER FOREIGN TABLE
postgres=# select * from fparent;
ERROR: attribute "a" of relation "fchild1" does not match parent's type
Above error, AIUI, is hit much before it is determined that fparent is a
foreign table, whereas the following is FDW-specific (waiting to happen) error,
postgres=# alter foreign table fparent add b char;
ALTER FOREIGN TABLE
postgres=# SELECT * FROM fparent;
ERROR: column "b" does not exist
CONTEXT: Remote SQL command: SELECT a, b FROM public.parent
Not sure if the first case could be considered s a bug as foreign tables are
pretty lax in these regards anyway.
I think the first case would be a bug caused by ATSimpleRecursion() that
doesn't allow the recursion. But I don't think the second case is a
bug. As described in the notes in the reference page on ALTER FOREIGN
TABLE, I think it should be the user's responsibility to ensure that the
foreign table definition matches the reality.
Best regards,
Etsuro Fujita
*** a/src/backend/commands/tablecmds.c
--- b/src/backend/commands/tablecmds.c
***************
*** 4367,4376 **** ATSimpleRecursion(List **wqueue, Relation rel,
AlterTableCmd *cmd, bool recurse, LOCKMODE lockmode)
{
/*
! * Propagate to children if desired. Non-table relations never have
! * children, so no need to search in that case.
*/
! if (recurse && rel->rd_rel->relkind == RELKIND_RELATION)
{
Oid relid = RelationGetRelid(rel);
ListCell *child;
--- 4367,4379 ----
AlterTableCmd *cmd, bool recurse, LOCKMODE lockmode)
{
/*
! * Propagate to children if desired. Relations other than plain tables
! * and foreign tables never have children, so no need to search in that
! * case.
*/
! if (recurse &&
! (rel->rd_rel->relkind == RELKIND_RELATION ||
! rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE))
{
Oid relid = RelationGetRelid(rel);
ListCell *child;
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