From fe2ef429a19b25903438b882ce16617a6e700d0f Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 17 Dec 2012 20:15:39 -0500 Subject: [PATCH] Fix failure to ignore leftover temp tables after a server crash. During crash recovery, we remove disk files belonging to temporary tables, but the system catalog entries for such tables are intentionally not cleaned up right away. Instead, the first backend that uses a temp schema is expected to clean out any leftover objects therein. This approach requires that we be careful to ignore leftover temp tables (since any actual access attempt would fail), *even if their BackendId matches our session*, if we have not yet established use of the session's corresponding temp schema. That worked fine in the past, but was broken by commit debcec7dc31a992703911a9953e299c8d730c778 which incorrectly removed the rd_islocaltemp relcache flag. Put it back, and undo various changes that substituted tests like "rel->rd_backend == MyBackendId" for use of a state-aware flag. Per trouble report from Heikki Linnakangas. Back-patch to 9.1 where the erroneous change was made. In the back branches, be careful to add rd_islocaltemp in a spot in the struct that was alignment padding before, so as not to break existing add-on code. --- src/backend/catalog/toasting.c | 2 +- src/backend/commands/copy.c | 2 +- src/backend/commands/sequence.c | 4 ++-- src/backend/commands/tablecmds.c | 33 ++++++++++++++++++++++++++---- src/backend/utils/adt/dbsize.c | 5 ++++- src/backend/utils/cache/relcache.c | 25 ++++++++++++++++++---- src/include/utils/rel.h | 17 ++++++--------- 7 files changed, 64 insertions(+), 24 deletions(-) diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c index 707ba7e283..0013c3f627 100644 --- a/src/backend/catalog/toasting.c +++ b/src/backend/catalog/toasting.c @@ -198,7 +198,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid, Datum reloptio * Toast tables for regular relations go in pg_toast; those for temp * relations go into the per-backend temp-toast-table namespace. */ - if (RelationUsesTempNamespace(rel)) + if (isTempOrToastNamespace(rel->rd_rel->relnamespace)) namespaceid = GetTempToastNamespace(); else namespaceid = PG_TOAST_NAMESPACE; diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c index 98bcb2fcf3..cd6b13c09f 100644 --- a/src/backend/commands/copy.c +++ b/src/backend/commands/copy.c @@ -800,7 +800,7 @@ DoCopy(const CopyStmt *stmt, const char *queryString) Assert(rel); /* check read-only transaction */ - if (XactReadOnly && rel->rd_backend != MyBackendId) + if (XactReadOnly && !rel->rd_islocaltemp) PreventCommandIfReadOnly("COPY FROM"); cstate = BeginCopyFrom(rel, stmt->filename, diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c index fbb6489915..c6cf44a8a8 100644 --- a/src/backend/commands/sequence.c +++ b/src/backend/commands/sequence.c @@ -552,7 +552,7 @@ nextval_internal(Oid relid) RelationGetRelationName(seqrel)))); /* read-only transactions may only modify temp sequences */ - if (seqrel->rd_backend != MyBackendId) + if (!seqrel->rd_islocaltemp) PreventCommandIfReadOnly("nextval()"); if (elm->last != elm->cached) /* some numbers were cached */ @@ -845,7 +845,7 @@ do_setval(Oid relid, int64 next, bool iscalled) RelationGetRelationName(seqrel)))); /* read-only transactions may only modify temp sequences */ - if (seqrel->rd_backend != MyBackendId) + if (!seqrel->rd_islocaltemp) PreventCommandIfReadOnly("setval()"); /* lock page' buffer and read tuple */ diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index ab5ab940ad..5d64461cda 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -1450,13 +1450,20 @@ MergeAttributes(List *schema, List *supers, char relpersistence, errmsg("inherited relation \"%s\" is not a table", parent->relname))); /* Permanent rels cannot inherit from temporary ones */ - if (relpersistence != RELPERSISTENCE_TEMP - && RelationUsesTempNamespace(relation)) + if (relpersistence != RELPERSISTENCE_TEMP && + relation->rd_rel->relpersistence == RELPERSISTENCE_TEMP) ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), errmsg("cannot inherit from temporary relation \"%s\"", parent->relname))); + /* If existing rel is temp, it must belong to this session */ + if (relation->rd_rel->relpersistence == RELPERSISTENCE_TEMP && + !relation->rd_islocaltemp) + ereport(ERROR, + (errcode(ERRCODE_WRONG_OBJECT_TYPE), + errmsg("cannot inherit from temporary relation of another session"))); + /* * We should have an UNDER permission flag for this, but for now, * demand that creator of a child table own the parent. @@ -5767,6 +5774,10 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel, ereport(ERROR, (errcode(ERRCODE_INVALID_TABLE_DEFINITION), errmsg("constraints on temporary tables may reference only temporary tables"))); + if (!pkrel->rd_islocaltemp || !rel->rd_islocaltemp) + ereport(ERROR, + (errcode(ERRCODE_INVALID_TABLE_DEFINITION), + errmsg("constraints on temporary tables must involve temporary tables of this session"))); break; } @@ -8905,13 +8916,27 @@ ATExecAddInherit(Relation child_rel, RangeVar *parent, LOCKMODE lockmode) ATSimplePermissions(parent_rel, ATT_TABLE); /* Permanent rels cannot inherit from temporary ones */ - if (RelationUsesTempNamespace(parent_rel) - && !RelationUsesTempNamespace(child_rel)) + if (parent_rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP && + child_rel->rd_rel->relpersistence != RELPERSISTENCE_TEMP) ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), errmsg("cannot inherit from temporary relation \"%s\"", RelationGetRelationName(parent_rel)))); + /* If parent rel is temp, it must belong to this session */ + if (parent_rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP && + !parent_rel->rd_islocaltemp) + ereport(ERROR, + (errcode(ERRCODE_WRONG_OBJECT_TYPE), + errmsg("cannot inherit from temporary relation of another session"))); + + /* Ditto for the child */ + if (child_rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP && + !child_rel->rd_islocaltemp) + ereport(ERROR, + (errcode(ERRCODE_WRONG_OBJECT_TYPE), + errmsg("cannot inherit to temporary relation of another session"))); + /* * Check for duplicates in the list of parents, and determine the highest * inhseqno already present; we'll use the next one for the new parent. diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c index 2ccdc0cee6..03975fcea4 100644 --- a/src/backend/utils/adt/dbsize.c +++ b/src/backend/utils/adt/dbsize.c @@ -259,6 +259,9 @@ pg_tablespace_size_name(PG_FUNCTION_ARGS) /* * calculate size of (one fork of) a relation + * + * Note: we can safely apply this to temp tables of other sessions, so there + * is no check here or at the call sites for that. */ static int64 calculate_relation_size(RelFileNode *rfn, BackendId backend, ForkNumber forknum) @@ -313,7 +316,7 @@ pg_relation_size(PG_FUNCTION_ARGS) * that makes queries like "SELECT pg_relation_size(oid) FROM pg_class" * less robust, because while we scan pg_class with an MVCC snapshot, * someone else might drop the table. It's better to return NULL for - * alread-dropped tables than throw an error and abort the whole query. + * already-dropped tables than throw an error and abort the whole query. */ if (rel == NULL) PG_RETURN_NULL(); diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a64d739ceb..bd7f567f1e 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -852,20 +852,33 @@ RelationBuildDesc(Oid targetRelId, bool insertIt) case RELPERSISTENCE_UNLOGGED: case RELPERSISTENCE_PERMANENT: relation->rd_backend = InvalidBackendId; + relation->rd_islocaltemp = false; break; case RELPERSISTENCE_TEMP: if (isTempOrToastNamespace(relation->rd_rel->relnamespace)) + { relation->rd_backend = MyBackendId; + relation->rd_islocaltemp = true; + } else { /* - * If it's a local temp table, but not one of ours, we have to - * use the slow, grotty method to figure out the owning - * backend. + * If it's a temp table, but not one of ours, we have to use + * the slow, grotty method to figure out the owning backend. + * + * Note: it's possible that rd_backend gets set to MyBackendId + * here, in case we are looking at a pg_class entry left over + * from a crashed backend that coincidentally had the same + * BackendId we're using. We should *not* consider such a + * table to be "ours"; this is why we need the separate + * rd_islocaltemp flag. The pg_class entry will get flushed + * if/when we clean out the corresponding temp table namespace + * in preparation for using it. */ relation->rd_backend = GetTempNamespaceBackendId(relation->rd_rel->relnamespace); Assert(relation->rd_backend != InvalidBackendId); + relation->rd_islocaltemp = false; } break; default: @@ -1386,6 +1399,7 @@ formrdesc(const char *relationName, Oid relationReltype, relation->rd_createSubid = InvalidSubTransactionId; relation->rd_newRelfilenodeSubid = InvalidSubTransactionId; relation->rd_backend = InvalidBackendId; + relation->rd_islocaltemp = false; /* * initialize relation tuple form @@ -2535,16 +2549,19 @@ RelationBuildLocalRelation(const char *relname, /* needed when bootstrapping: */ rel->rd_rel->relowner = BOOTSTRAP_SUPERUSERID; - /* set up persistence; rd_backend is a function of persistence type */ + /* set up persistence and relcache fields dependent on it */ rel->rd_rel->relpersistence = relpersistence; switch (relpersistence) { case RELPERSISTENCE_UNLOGGED: case RELPERSISTENCE_PERMANENT: rel->rd_backend = InvalidBackendId; + rel->rd_islocaltemp = false; break; case RELPERSISTENCE_TEMP: + Assert(isTempOrToastNamespace(relnamespace)); rel->rd_backend = MyBackendId; + rel->rd_islocaltemp = true; break; default: elog(ERROR, "invalid relpersistence: %c", relpersistence); diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h index 4669d8a67e..3bf90d28f9 100644 --- a/src/include/utils/rel.h +++ b/src/include/utils/rel.h @@ -85,6 +85,7 @@ typedef struct RelationData bool rd_isvalid; /* relcache entry is valid */ char rd_indexvalid; /* state of rd_indexlist: 0 = not valid, 1 = * valid, 2 = temporarily forced */ + bool rd_islocaltemp; /* rel is a temp rel of this session */ /* * rd_createSubid is the ID of the highest subtransaction the rel has @@ -362,22 +363,16 @@ typedef struct StdRdOptions #define RelationUsesLocalBuffers(relation) \ ((relation)->rd_rel->relpersistence == RELPERSISTENCE_TEMP) -/* - * RelationUsesTempNamespace - * True if relation's catalog entries live in a private namespace. - */ -#define RelationUsesTempNamespace(relation) \ - ((relation)->rd_rel->relpersistence == RELPERSISTENCE_TEMP) - /* * RELATION_IS_LOCAL * If a rel is either temp or newly created in the current transaction, - * it can be assumed to be visible only to the current backend. + * it can be assumed to be accessible only to the current backend. + * This is typically used to decide that we can skip acquiring locks. * * Beware of multiple eval of argument */ #define RELATION_IS_LOCAL(relation) \ - ((relation)->rd_backend == MyBackendId || \ + ((relation)->rd_islocaltemp || \ (relation)->rd_createSubid != InvalidSubTransactionId) /* @@ -387,8 +382,8 @@ typedef struct StdRdOptions * Beware of multiple eval of argument */ #define RELATION_IS_OTHER_TEMP(relation) \ - ((relation)->rd_rel->relpersistence == RELPERSISTENCE_TEMP \ - && (relation)->rd_backend != MyBackendId) + ((relation)->rd_rel->relpersistence == RELPERSISTENCE_TEMP && \ + !(relation)->rd_islocaltemp) /* routines in utils/cache/relcache.c */ extern void RelationIncrementReferenceCount(Relation rel); -- 2.40.0