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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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8
src/backend/utils/cache/inval.c vendored
View File

@ -1040,15 +1040,15 @@ CacheInvalidateHeapTuple(Relation relation,
/*
* We only need to worry about invalidation for tuples that are in system
* relations; user-relation tuples are never in catcaches and can't affect
* catalogs; user-relation tuples are never in catcaches and can't affect
* the relcache either.
*/
if (!IsSystemRelation(relation))
if (!IsCatalogRelation(relation))
return;
/*
* TOAST tuples can likewise be ignored here. Note that TOAST tables are
* considered system relations so they are not filtered by the above test.
* IsCatalogRelation() will return true for TOAST tables of system
* catalogs, but we don't care about those, either.
*/
if (IsToastRelation(relation))
return;