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Refine our definition of what constitutes a system relation.

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Although user-defined relations can't be directly created in
pg_catalog, it's possible for them to end up there, because you can
create them in some other schema and then use ALTER TABLE .. SET SCHEMA
to move them there.  Previously, such relations couldn't afterwards
be manipulated, because IsSystemRelation()/IsSystemClass() rejected
all attempts to modify objects in the pg_catalog schema, regardless
of their origin.  With this patch, they now reject only those
objects in pg_catalog which were created at initdb-time, allowing
most operations on user-created tables in pg_catalog to proceed
normally.

This patch also adds new functions IsCatalogRelation() and
IsCatalogClass(), which is similar to IsSystemRelation() and
IsSystemClass() but with a slightly narrower definition: only TOAST
tables of system catalogs are included, rather than *all* TOAST tables.
This is currently used only for making decisions about when
invalidation messages need to be sent, but upcoming logical decoding
patches will find other uses for this information.

Andres Freund, with some modifications by me.
This commit is contained in:
Robert Haas
2013-11-28 20:57:20 -05:00
parent 2fe69cacff
commit 8e18d04d4d
15 changed files with 149 additions and 31 deletions
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28
src/test/regress/sql/alter_table.sql
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@ -1567,3 +1567,31 @@ FROM (
FROM pg_class
WHERE relkind IN ('r', 'i', 'S', 't', 'm')
) mapped;
-- Checks on creating and manipulation of user defined relations in
-- pg_catalog.
--
-- XXX: It would be useful to add checks around trying to manipulate
-- catalog tables, but that might have ugly consequences when run
-- against an existing server with allow_system_table_mods = on.
SHOW allow_system_table_mods;
-- disallowed because of search_path issues with pg_dump
CREATE TABLE pg_catalog.new_system_table();
-- instead create in public first, move to catalog
CREATE TABLE new_system_table(id serial primary key, othercol text);
ALTER TABLE new_system_table SET SCHEMA pg_catalog;
-- XXX: it's currently impossible to move relations out of pg_catalog
ALTER TABLE new_system_table SET SCHEMA public;
-- move back, will currently error out, already there
ALTER TABLE new_system_table SET SCHEMA pg_catalog;
ALTER TABLE new_system_table RENAME TO old_system_table;
CREATE INDEX old_system_table__othercol ON old_system_table (othercol);
INSERT INTO old_system_table(othercol) VALUES ('somedata'), ('otherdata');
UPDATE old_system_table SET id = -id;
DELETE FROM old_system_table WHERE othercol = 'somedata';
TRUNCATE old_system_table;
ALTER TABLE old_system_table DROP CONSTRAINT new_system_table_pkey;
ALTER TABLE old_system_table DROP COLUMN othercol;
DROP TABLE old_system_table;