rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
postgresql/src/include/access/multixact.h

69 lines
2.2 KiB
C
Raw Normal View History

Implement sharable row-level locks, and use them for foreign key references to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.
2005-04-28 23:47:18 +02:00
/*
* multixact.h
*
* PostgreSQL multi-transaction-log manager
*
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
Standard pgindent run for 8.1.
2005-10-15 04:49:52 +02:00
* $PostgreSQL: pgsql/src/include/access/multixact.h,v 1.7 2005/10/15 02:49:42 momjian Exp $
Implement sharable row-level locks, and use them for foreign key references to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.
2005-04-28 23:47:18 +02:00
*/
#ifndef MULTIXACT_H
#define MULTIXACT_H
Change WAL-logging scheme for multixacts to be more like regular transaction IDs, rather than like subtrans; in particular, the information now survives a database restart. Per previous discussion, this is essential for PITR log shipping and for 2PC.
2005-06-08 17:50:28 +02:00
#include "access/xlog.h"
Implement sharable row-level locks, and use them for foreign key references to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.
2005-04-28 23:47:18 +02:00
#define InvalidMultiXactId ((MultiXactId) 0)
#define FirstMultiXactId ((MultiXactId) 1)
#define MultiXactIdIsValid(multi) ((multi) != InvalidMultiXactId)
Change WAL-logging scheme for multixacts to be more like regular transaction IDs, rather than like subtrans; in particular, the information now survives a database restart. Per previous discussion, this is essential for PITR log shipping and for 2PC.
2005-06-08 17:50:28 +02:00
/* ----------------
* multixact-related XLOG entries
* ----------------
*/
#define XLOG_MULTIXACT_ZERO_OFF_PAGE 0x00
#define XLOG_MULTIXACT_ZERO_MEM_PAGE 0x10
#define XLOG_MULTIXACT_CREATE_ID 0x20
typedef struct xl_multixact_create
{
Standard pgindent run for 8.1.
2005-10-15 04:49:52 +02:00
MultiXactId mid; /* new MultiXact's ID */
MultiXactOffset moff; /* its starting offset in members file */
int32 nxids; /* number of member XIDs */
TransactionId xids[1]; /* VARIABLE LENGTH ARRAY */
Change WAL-logging scheme for multixacts to be more like regular transaction IDs, rather than like subtrans; in particular, the information now survives a database restart. Per previous discussion, this is essential for PITR log shipping and for 2PC.
2005-06-08 17:50:28 +02:00
} xl_multixact_create;
#define MinSizeOfMultiXactCreate offsetof(xl_multixact_create, xids)
Clean up MultiXactIdExpand's API by separating out the case where we are creating a new MultiXactId from two regular XIDs. The original coding was unnecessarily complicated and didn't save any code anyway.
2005-05-03 21:42:41 +02:00
extern MultiXactId MultiXactIdCreate(TransactionId xid1, TransactionId xid2);
extern MultiXactId MultiXactIdExpand(MultiXactId multi, TransactionId xid);
Implement sharable row-level locks, and use them for foreign key references to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.
2005-04-28 23:47:18 +02:00
extern bool MultiXactIdIsRunning(MultiXactId multi);
Clean up MultiXactIdExpand's API by separating out the case where we are creating a new MultiXactId from two regular XIDs. The original coding was unnecessarily complicated and didn't save any code anyway.
2005-05-03 21:42:41 +02:00
extern void MultiXactIdWait(MultiXactId multi);
Add NOWAIT option to SELECT FOR UPDATE/SHARE. Original patch by Hans-Juergen Schoenig, revisions by Karel Zak and Tom Lane.
2005-08-01 22:31:16 +02:00
extern bool ConditionalMultiXactIdWait(MultiXactId multi);
Implement sharable row-level locks, and use them for foreign key references to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.
2005-04-28 23:47:18 +02:00
extern void MultiXactIdSetOldestMember(void);
Standard pgindent run for 8.1.
2005-10-15 04:49:52 +02:00
extern int GetMultiXactIdMembers(MultiXactId multi, TransactionId **xids);
Implement sharable row-level locks, and use them for foreign key references to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.
2005-04-28 23:47:18 +02:00
extern void AtEOXact_MultiXact(void);
Convert the arithmetic for shared memory size calculation from 'int' to 'Size' (that is, size_t), and install overflow detection checks in it. This allows us to remove the former arbitrary restrictions on NBuffers etc. It won't make any difference in a 32-bit machine, but in a 64-bit machine you could theoretically have terabytes of shared buffers. (How efficiently we could manage 'em remains to be seen.) Similarly, num_temp_buffers, work_mem, and maintenance_work_mem can be set above 2Gb on a 64-bit machine. Original patch from Koichi Suzuki, additional work by moi.
2005-08-21 01:26:37 +02:00
extern Size MultiXactShmemSize(void);
Implement sharable row-level locks, and use them for foreign key references to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.
2005-04-28 23:47:18 +02:00
extern void MultiXactShmemInit(void);
extern void BootStrapMultiXact(void);
extern void StartupMultiXact(void);
extern void ShutdownMultiXact(void);
Change WAL-logging scheme for multixacts to be more like regular transaction IDs, rather than like subtrans; in particular, the information now survives a database restart. Per previous discussion, this is essential for PITR log shipping and for 2PC.
2005-06-08 17:50:28 +02:00
extern void MultiXactGetCheckptMulti(bool is_shutdown,
Standard pgindent run for 8.1.
2005-10-15 04:49:52 +02:00
MultiXactId *nextMulti,
MultiXactOffset *nextMultiOffset);
Implement sharable row-level locks, and use them for foreign key references to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.
2005-04-28 23:47:18 +02:00
extern void CheckPointMultiXact(void);
Change WAL-logging scheme for multixacts to be more like regular transaction IDs, rather than like subtrans; in particular, the information now survives a database restart. Per previous discussion, this is essential for PITR log shipping and for 2PC.
2005-06-08 17:50:28 +02:00
extern void MultiXactSetNextMXact(MultiXactId nextMulti,
Standard pgindent run for 8.1.
2005-10-15 04:49:52 +02:00
MultiXactOffset nextMultiOffset);
Change WAL-logging scheme for multixacts to be more like regular transaction IDs, rather than like subtrans; in particular, the information now survives a database restart. Per previous discussion, this is essential for PITR log shipping and for 2PC.
2005-06-08 17:50:28 +02:00
extern void MultiXactAdvanceNextMXact(MultiXactId minMulti,
Standard pgindent run for 8.1.
2005-10-15 04:49:52 +02:00
MultiXactOffset minMultiOffset);
Change WAL-logging scheme for multixacts to be more like regular transaction IDs, rather than like subtrans; in particular, the information now survives a database restart. Per previous discussion, this is essential for PITR log shipping and for 2PC.
2005-06-08 17:50:28 +02:00
extern void multixact_redo(XLogRecPtr lsn, XLogRecord *record);
extern void multixact_desc(char *buf, uint8 xl_info, char *rec);
Implement sharable row-level locks, and use them for foreign key references to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.
2005-04-28 23:47:18 +02:00
#endif /* MULTIXACT_H */