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lockdefs.h
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1/*-------------------------------------------------------------------------
2 *
3 * lockdefs.h
4 * Frontend exposed parts of postgres' low level lock mechanism
5 *
6 * The split between lockdefs.h and lock.h is not very principled. This file
7 * contains definition that have to (indirectly) be available when included by
8 * FRONTEND code.
9 *
10 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
11 * Portions Copyright (c) 1994, Regents of the University of California
12 *
13 * src/include/storage/lockdefs.h
14 *
15 *-------------------------------------------------------------------------
16 */
17#ifndef LOCKDEFS_H_
18#define LOCKDEFS_H_
19
20/*
21 * LOCKMODE is an integer (1..N) indicating a lock type. LOCKMASK is a bit
22 * mask indicating a set of held or requested lock types (the bit 1<<mode
23 * corresponds to a particular lock mode).
24 */
25typedef int LOCKMASK;
26typedef int LOCKMODE;
27
28/*
29 * These are the valid values of type LOCKMODE for all the standard lock
30 * methods (both DEFAULT and USER).
31 */
32
33/* NoLock is not a lock mode, but a flag value meaning "don't get a lock" */
34#define NoLock 0
35
36#define AccessShareLock 1 /* SELECT */
37#define RowShareLock 2 /* SELECT FOR UPDATE/FOR SHARE */
38#define RowExclusiveLock 3 /* INSERT, UPDATE, DELETE */
39#define ShareUpdateExclusiveLock 4 /* VACUUM (non-FULL), ANALYZE, CREATE
40 * INDEX CONCURRENTLY */
41#define ShareLock 5 /* CREATE INDEX (WITHOUT CONCURRENTLY) */
42#define ShareRowExclusiveLock 6 /* like EXCLUSIVE MODE, but allows ROW
43 * SHARE */
44#define ExclusiveLock 7 /* blocks ROW SHARE/SELECT...FOR UPDATE */
45#define AccessExclusiveLock 8 /* ALTER TABLE, DROP TABLE, VACUUM FULL,
46 * and unqualified LOCK TABLE */
47
48#define MaxLockMode 8 /* highest standard lock mode */
49
50/* See README.tuplock section "Locking to write inplace-updated tables" */
51#define InplaceUpdateTupleLock ExclusiveLock
52
53/* WAL representation of an AccessExclusiveLock on a table */
54typedef struct xl_standby_lock
56 TransactionId xid; /* xid of holder of AccessExclusiveLock */
57 Oid dbOid; /* DB containing table */
58 Oid relOid; /* OID of table */
60
61#endif /* LOCKDEFS_H_ */
uint32 TransactionId
Definition: c.h:623
int LOCKMODE
Definition: lockdefs.h:26
int LOCKMASK
Definition: lockdefs.h:25
struct xl_standby_lock xl_standby_lock
unsigned int Oid
Definition: postgres_ext.h:32
TransactionId xid
Definition: lockdefs.h:53