From 97d89101045fac8cb36f4ef6c08526ea0841a596 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Fri, 30 Jun 2023 07:49:01 +0900 Subject: [PATCH] Fix pg_depend entry to AMs after ALTER TABLE .. SET ACCESS METHOD ALTER TABLE .. SET ACCESS METHOD was not registering a dependency to the new access method with the relation altered in its rewrite phase, making possible the drop of an access method even if there are relations that depend on it. During the rewrite, a temporary relation is created to build the new relation files before swapping the new and old files, and, while the temporary relation was registering a correct dependency to the new AM, the old relation did not do that. A dependency on the access method is added when the relation files are swapped, which is the point where pg_class is updated. Materialized views and tables use the same code path, hence both were impacted. Backpatch down to 15, where this command has been introduced. Reported-by: Alexander Lakhin Reviewed-by: Nathan Bossart, Andres Freund Discussion: https://postgr.es/m/18000-9145c25b1af475ca@postgresql.org Backpatch-through: 15 --- src/backend/commands/cluster.c | 29 +++++++++++++++++++++++++ src/test/regress/expected/create_am.out | 29 +++++++++++++++++++++++++ src/test/regress/sql/create_am.sql | 18 +++++++++++++++ 3 files changed, 76 insertions(+) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3bfabb6d10..03b24ab90f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1070,6 +1070,8 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, relfilenumber2; RelFileNumber swaptemp; char swptmpchr; + Oid relam1, + relam2; /* We need writable copies of both pg_class tuples. */ relRelation = table_open(RelationRelationId, RowExclusiveLock); @@ -1086,6 +1088,8 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, relfilenumber1 = relform1->relfilenode; relfilenumber2 = relform2->relfilenode; + relam1 = relform1->relam; + relam2 = relform2->relam; if (RelFileNumberIsValid(relfilenumber1) && RelFileNumberIsValid(relfilenumber2)) @@ -1257,6 +1261,31 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, CacheInvalidateRelcacheByTuple(reltup2); } + /* + * Now that pg_class has been updated with its relevant information for + * the swap, update the dependency of the relations to point to their new + * table AM, if it has changed. + */ + if (relam1 != relam2) + { + if (changeDependencyFor(RelationRelationId, + r1, + AccessMethodRelationId, + relam1, + relam2) != 1) + elog(ERROR, "failed to change access method dependency for relation \"%s.%s\"", + get_namespace_name(get_rel_namespace(r1)), + get_rel_name(r1)); + if (changeDependencyFor(RelationRelationId, + r2, + AccessMethodRelationId, + relam2, + relam1) != 1) + elog(ERROR, "failed to change access method dependency for relation \"%s.%s\"", + get_namespace_name(get_rel_namespace(r2)), + get_rel_name(r2)); + } + /* * Post alter hook for modified relations. The change to r2 is always * internal, but r1 depends on the invocation context. diff --git a/src/test/regress/expected/create_am.out b/src/test/regress/expected/create_am.out index e9a9283d7a..b50293d514 100644 --- a/src/test/regress/expected/create_am.out +++ b/src/test/regress/expected/create_am.out @@ -240,6 +240,35 @@ SELECT amname FROM pg_class c, pg_am am heap (1 row) +-- Switching to heap2 adds new dependency entry to the AM. +ALTER TABLE heaptable SET ACCESS METHOD heap2; +SELECT pg_describe_object(classid, objid, objsubid) as obj, + pg_describe_object(refclassid, refobjid, refobjsubid) as objref, + deptype + FROM pg_depend + WHERE classid = 'pg_class'::regclass AND + objid = 'heaptable'::regclass + ORDER BY 1, 2; + obj | objref | deptype +-----------------+---------------------+--------- + table heaptable | access method heap2 | n + table heaptable | schema public | n +(2 rows) + +-- Switching to heap should not have a dependency entry to the AM. +ALTER TABLE heaptable SET ACCESS METHOD heap; +SELECT pg_describe_object(classid, objid, objsubid) as obj, + pg_describe_object(refclassid, refobjid, refobjsubid) as objref, + deptype + FROM pg_depend + WHERE classid = 'pg_class'::regclass AND + objid = 'heaptable'::regclass + ORDER BY 1, 2; + obj | objref | deptype +-----------------+---------------+--------- + table heaptable | schema public | n +(1 row) + ALTER TABLE heaptable SET ACCESS METHOD heap2; SELECT amname FROM pg_class c, pg_am am WHERE c.relam = am.oid AND c.oid = 'heaptable'::regclass; diff --git a/src/test/regress/sql/create_am.sql b/src/test/regress/sql/create_am.sql index 256884c959..2785ffd8bb 100644 --- a/src/test/regress/sql/create_am.sql +++ b/src/test/regress/sql/create_am.sql @@ -166,6 +166,24 @@ CREATE TABLE heaptable USING heap AS SELECT a, repeat(a::text, 100) FROM generate_series(1,9) AS a; SELECT amname FROM pg_class c, pg_am am WHERE c.relam = am.oid AND c.oid = 'heaptable'::regclass; +-- Switching to heap2 adds new dependency entry to the AM. +ALTER TABLE heaptable SET ACCESS METHOD heap2; +SELECT pg_describe_object(classid, objid, objsubid) as obj, + pg_describe_object(refclassid, refobjid, refobjsubid) as objref, + deptype + FROM pg_depend + WHERE classid = 'pg_class'::regclass AND + objid = 'heaptable'::regclass + ORDER BY 1, 2; +-- Switching to heap should not have a dependency entry to the AM. +ALTER TABLE heaptable SET ACCESS METHOD heap; +SELECT pg_describe_object(classid, objid, objsubid) as obj, + pg_describe_object(refclassid, refobjid, refobjsubid) as objref, + deptype + FROM pg_depend + WHERE classid = 'pg_class'::regclass AND + objid = 'heaptable'::regclass + ORDER BY 1, 2; ALTER TABLE heaptable SET ACCESS METHOD heap2; SELECT amname FROM pg_class c, pg_am am WHERE c.relam = am.oid AND c.oid = 'heaptable'::regclass;