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Truncating or dropping a table is treated like deletion of all tuples, and check for conflicts accordingly. If a table is clustered or rewritten by ALTER TABLE, all predicate locks on the heap are promoted to relation-level locks, because the tuple or page ids of any existing tuples will change and won't be valid after rewriting the table. Arguably ALTER TABLE should be treated like a mass-UPDATE of every row, but if you e.g change the datatype of a column, you could also argue that it's just a change to the physical layout, not a logical change. Reindexing promotes all locks on the index to relation-level lock on the heap. Kevin Grittner, with a lot of cosmetic changes by me.
70 lines
2.5 KiB
C
70 lines
2.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* predicate.h
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* POSTGRES public predicate locking definitions.
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*
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*
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* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/storage/predicate.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PREDICATE_H
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#define PREDICATE_H
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#include "utils/relcache.h"
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#include "utils/snapshot.h"
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/*
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* GUC variables
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*/
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extern int max_predicate_locks_per_xact;
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/* Number of SLRU buffers to use for predicate locking */
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#define NUM_OLDSERXID_BUFFERS 16
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/*
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* function prototypes
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*/
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/* housekeeping for shared memory predicate lock structures */
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extern void InitPredicateLocks(void);
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extern Size PredicateLockShmemSize(void);
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extern void CheckPointPredicate(void);
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/* predicate lock reporting */
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extern bool PageIsPredicateLocked(const Relation relation, const BlockNumber blkno);
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/* predicate lock maintenance */
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extern Snapshot RegisterSerializableTransaction(Snapshot snapshot);
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extern void RegisterPredicateLockingXid(const TransactionId xid);
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extern void PredicateLockRelation(const Relation relation);
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extern void PredicateLockPage(const Relation relation, const BlockNumber blkno);
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extern void PredicateLockTuple(const Relation relation, const HeapTuple tuple);
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extern void PredicateLockPageSplit(const Relation relation, const BlockNumber oldblkno, const BlockNumber newblkno);
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extern void PredicateLockPageCombine(const Relation relation, const BlockNumber oldblkno, const BlockNumber newblkno);
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extern void TransferPredicateLocksToHeapRelation(const Relation relation);
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extern void ReleasePredicateLocks(const bool isCommit);
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/* conflict detection (may also trigger rollback) */
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extern void CheckForSerializableConflictOut(const bool valid, const Relation relation, const HeapTuple tuple, const Buffer buffer);
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extern void CheckForSerializableConflictIn(const Relation relation, const HeapTuple tuple, const Buffer buffer);
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extern void CheckTableForSerializableConflictIn(const Relation relation);
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/* final rollback checking */
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extern void PreCommit_CheckForSerializationFailure(void);
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/* two-phase commit support */
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extern void AtPrepare_PredicateLocks(void);
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extern void PostPrepare_PredicateLocks(TransactionId xid);
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extern void PredicateLockTwoPhaseFinish(TransactionId xid, bool isCommit);
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extern void predicatelock_twophase_recover(TransactionId xid, uint16 info,
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void *recdata, uint32 len);
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#endif /* PREDICATE_H */
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