From 5b4b07fa9ac34b2567d7e3ef67bfc17ab9aafbc4 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Wed, 22 Jan 2020 09:49:28 +0900 Subject: [PATCH] Fix concurrent indexing operations with temporary tables MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Attempting to use CREATE INDEX, DROP INDEX or REINDEX with CONCURRENTLY on a temporary relation with ON COMMIT actions triggered unexpected errors because those operations use multiple transactions internally to complete their work. Here is for example one confusing error when using ON COMMIT DELETE ROWS: ERROR: index "foo" already contains data Issues related to temporary relations and concurrent indexing are fixed in this commit by enforcing the non-concurrent path to be taken for temporary relations even if using CONCURRENTLY, transparently to the user. Using a non-concurrent path does not matter in practice as locks cannot be taken on a temporary relation by a session different than the one owning the relation, and the non-concurrent operation is more effective. The problem exists with REINDEX since v12 with the introduction of CONCURRENTLY, and with CREATE/DROP INDEX since CONCURRENTLY exists for those commands. In all supported versions, this caused only confusing error messages to be generated. Note that with REINDEX, it was also possible to issue a REINDEX CONCURRENTLY for a temporary relation owned by a different session, leading to a server crash. The idea to enforce transparently the non-concurrent code path for temporary relations comes originally from Andres Freund. Reported-by: Manuel Rigger Author: Michael Paquier, Heikki Linnakangas Reviewed-by: Andres Freund, Álvaro Herrera, Heikki Linnakangas Discussion: https://postgr.es/m/CA+u7OA6gP7YAeCguyseusYcc=uR8+ypjCcgDDCTzjQ+k6S9ksQ@mail.gmail.com Backpatch-through: 9.4 --- doc/src/sgml/ref/create_index.sgml | 5 ++++ doc/src/sgml/ref/drop_index.sgml | 5 ++++ src/backend/catalog/index.c | 9 ++++++ src/backend/commands/indexcmds.c | 33 +++++++++++++++++----- src/backend/commands/tablecmds.c | 18 +++++++++++- src/test/regress/expected/create_index.out | 25 ++++++++++++++++ src/test/regress/sql/create_index.sql | 25 ++++++++++++++++ 7 files changed, 112 insertions(+), 8 deletions(-) diff --git a/doc/src/sgml/ref/create_index.sgml b/doc/src/sgml/ref/create_index.sgml index 3a4e71ca1c..2d34e44fff 100644 --- a/doc/src/sgml/ref/create_index.sgml +++ b/doc/src/sgml/ref/create_index.sgml @@ -129,6 +129,11 @@ CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ [ IF NOT EXISTS ] . + + For temporary tables, CREATE INDEX is always + non-concurrent, as no other session can access them, and + non-concurrent index creation is cheaper. + diff --git a/doc/src/sgml/ref/drop_index.sgml b/doc/src/sgml/ref/drop_index.sgml index 2a8ca5bf68..0aedd71bd6 100644 --- a/doc/src/sgml/ref/drop_index.sgml +++ b/doc/src/sgml/ref/drop_index.sgml @@ -58,6 +58,11 @@ DROP INDEX [ CONCURRENTLY ] [ IF EXISTS ] nameDROP INDEX CONCURRENTLY cannot. + + For temporary tables, DROP INDEX is always + non-concurrent, as no other session can access them, and + non-concurrent index drop is cheaper. + diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index bc20d7c750..bb7d981327 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1493,6 +1493,15 @@ index_drop(Oid indexId, bool concurrent) LOCKTAG heaplocktag; LOCKMODE lockmode; + /* + * A temporary relation uses a non-concurrent DROP. Other backends can't + * access a temporary relation, so there's no harm in grabbing a stronger + * lock (see comments in RemoveRelations), and a non-concurrent DROP is + * more efficient. + */ + Assert(get_rel_persistence(indexId) != RELPERSISTENCE_TEMP || + !concurrent); + /* * To drop an index safely, we must grab exclusive lock on its parent * table. Exclusive lock on the index alone is insufficient because diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c index 1faaaf625d..568a32bb4e 100644 --- a/src/backend/commands/indexcmds.c +++ b/src/backend/commands/indexcmds.c @@ -335,6 +335,7 @@ DefineIndex(Oid relationId, bool skip_build, bool quiet) { + bool concurrent; char *indexRelationName; char *accessMethodName; Oid *typeObjectId; @@ -371,6 +372,18 @@ DefineIndex(Oid relationId, Snapshot snapshot; int i; + /* + * Force non-concurrent build on temporary relations, even if CONCURRENTLY + * was requested. Other backends can't access a temporary relation, so + * there's no harm in grabbing a stronger lock, and a non-concurrent DROP + * is more efficient. Do this before any use of the concurrent option is + * done. + */ + if (stmt->concurrent && get_rel_persistence(relationId) != RELPERSISTENCE_TEMP) + concurrent = true; + else + concurrent = false; + /* * count key attributes in index */ @@ -413,7 +426,7 @@ DefineIndex(Oid relationId, * parallel workers under the control of certain particular ambuild * functions will need to be updated, too. */ - lockmode = stmt->concurrent ? ShareUpdateExclusiveLock : ShareLock; + lockmode = concurrent ? ShareUpdateExclusiveLock : ShareLock; rel = heap_open(relationId, lockmode); relationId = RelationGetRelid(rel); @@ -457,6 +470,12 @@ DefineIndex(Oid relationId, partitioned = rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE; if (partitioned) { + /* + * Note: we check 'stmt->concurrent' rather than 'concurrent', so that + * the error is thrown also for temporary tables. Seems better to be + * consistent, even though we could do it on temporary table because + * we're not actually doing it concurrently. + */ if (stmt->concurrent) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), @@ -645,8 +664,8 @@ DefineIndex(Oid relationId, indexInfo->ii_ExclusionStrats = NULL; indexInfo->ii_Unique = stmt->unique; /* In a concurrent build, mark it not-ready-for-inserts */ - indexInfo->ii_ReadyForInserts = !stmt->concurrent; - indexInfo->ii_Concurrent = stmt->concurrent; + indexInfo->ii_ReadyForInserts = !concurrent; + indexInfo->ii_Concurrent = concurrent; indexInfo->ii_BrokenHotChain = false; indexInfo->ii_ParallelWorkers = 0; indexInfo->ii_Am = accessMethodId; @@ -814,7 +833,7 @@ DefineIndex(Oid relationId, * A valid stmt->oldNode implies that we already have a built form of the * index. The caller should also decline any index build. */ - Assert(!OidIsValid(stmt->oldNode) || (skip_build && !stmt->concurrent)); + Assert(!OidIsValid(stmt->oldNode) || (skip_build && !concurrent)); /* * Make the catalog entries for the index, including constraints. This @@ -825,11 +844,11 @@ DefineIndex(Oid relationId, flags = constr_flags = 0; if (stmt->isconstraint) flags |= INDEX_CREATE_ADD_CONSTRAINT; - if (skip_build || stmt->concurrent || partitioned) + if (skip_build || concurrent || partitioned) flags |= INDEX_CREATE_SKIP_BUILD; if (stmt->if_not_exists) flags |= INDEX_CREATE_IF_NOT_EXISTS; - if (stmt->concurrent) + if (concurrent) flags |= INDEX_CREATE_CONCURRENT; if (partitioned) flags |= INDEX_CREATE_PARTITIONED; @@ -1107,7 +1126,7 @@ DefineIndex(Oid relationId, return address; } - if (!stmt->concurrent) + if (!concurrent) { /* Close the heap and we're done, in the non-concurrent case */ heap_close(rel, NoLock); diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index a120a18f02..38386fb9cf 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -1106,7 +1106,11 @@ RemoveRelations(DropStmt *drop) /* DROP CONCURRENTLY uses a weaker lock, and has some restrictions */ if (drop->concurrent) { - flags |= PERFORM_DELETION_CONCURRENTLY; + /* + * Note that for temporary relations this lock may get upgraded + * later on, but as no other session can access a temporary + * relation, this is actually fine. + */ lockmode = ShareUpdateExclusiveLock; Assert(drop->removeType == OBJECT_INDEX); if (list_length(drop->objects) != 1) @@ -1197,6 +1201,18 @@ RemoveRelations(DropStmt *drop) continue; } + /* + * Decide if concurrent mode needs to be used here or not. The + * relation persistence cannot be known without its OID. + */ + if (drop->concurrent && + get_rel_persistence(relOid) != RELPERSISTENCE_TEMP) + { + Assert(list_length(drop->objects) == 1 && + drop->removeType == OBJECT_INDEX); + flags |= PERFORM_DELETION_CONCURRENTLY; + } + /* OK, we're ready to delete this one */ obj.classId = RelationRelationId; obj.objectId = relOid; diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out index e7d7c7aee6..c3deccca57 100644 --- a/src/test/regress/expected/create_index.out +++ b/src/test/regress/expected/create_index.out @@ -2571,6 +2571,31 @@ Indexes: "concur_index5" btree (f2) WHERE f1 = 'x'::text "std_index" btree (f2) +-- Temporary tables with concurrent builds and on-commit actions +-- CONCURRENTLY used with CREATE INDEX and DROP INDEX is ignored. +-- PRESERVE ROWS, the default. +CREATE TEMP TABLE concur_temp (f1 int, f2 text) + ON COMMIT PRESERVE ROWS; +INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar'); +CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1); +DROP INDEX CONCURRENTLY concur_temp_ind; +DROP TABLE concur_temp; +-- ON COMMIT DROP +BEGIN; +CREATE TEMP TABLE concur_temp (f1 int, f2 text) + ON COMMIT DROP; +INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar'); +-- Fails when running in a transaction. +CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1); +ERROR: CREATE INDEX CONCURRENTLY cannot run inside a transaction block +COMMIT; +-- ON COMMIT DELETE ROWS +CREATE TEMP TABLE concur_temp (f1 int, f2 text) + ON COMMIT DELETE ROWS; +INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar'); +CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1); +DROP INDEX CONCURRENTLY concur_temp_ind; +DROP TABLE concur_temp; -- -- Try some concurrent index drops -- diff --git a/src/test/regress/sql/create_index.sql b/src/test/regress/sql/create_index.sql index 283c4e6c18..668076e215 100644 --- a/src/test/regress/sql/create_index.sql +++ b/src/test/regress/sql/create_index.sql @@ -825,6 +825,31 @@ VACUUM FULL concur_heap; REINDEX TABLE concur_heap; \d concur_heap +-- Temporary tables with concurrent builds and on-commit actions +-- CONCURRENTLY used with CREATE INDEX and DROP INDEX is ignored. +-- PRESERVE ROWS, the default. +CREATE TEMP TABLE concur_temp (f1 int, f2 text) + ON COMMIT PRESERVE ROWS; +INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar'); +CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1); +DROP INDEX CONCURRENTLY concur_temp_ind; +DROP TABLE concur_temp; +-- ON COMMIT DROP +BEGIN; +CREATE TEMP TABLE concur_temp (f1 int, f2 text) + ON COMMIT DROP; +INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar'); +-- Fails when running in a transaction. +CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1); +COMMIT; +-- ON COMMIT DELETE ROWS +CREATE TEMP TABLE concur_temp (f1 int, f2 text) + ON COMMIT DELETE ROWS; +INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar'); +CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1); +DROP INDEX CONCURRENTLY concur_temp_ind; +DROP TABLE concur_temp; + -- -- Try some concurrent index drops --