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postgresql/src/include/access/clog.h

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Replace implementation of pg_log as a relation accessed through the buffer manager with 'pg_clog', a specialized access method modeled on pg_xlog. This simplifies startup (don't need to play games to open pg_log; among other things, OverrideTransactionSystem goes away), should improve performance a little, and opens the door to recycling commit log space by removing no-longer-needed segments of the commit log. Actual recycling is not there yet, but I felt I should commit this part separately since it'd still be useful if we chose not to do transaction ID wraparound.
2001-08-25 20:52:43 +02:00
/*
* clog.h
*
* PostgreSQL transaction-commit-log manager
*
Stamp copyrights for year 2011.
2011-01-01 19:18:15 +01:00
* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
Replace implementation of pg_log as a relation accessed through the buffer manager with 'pg_clog', a specialized access method modeled on pg_xlog. This simplifies startup (don't need to play games to open pg_log; among other things, OverrideTransactionSystem goes away), should improve performance a little, and opens the door to recycling commit log space by removing no-longer-needed segments of the commit log. Actual recycling is not there yet, but I felt I should commit this part separately since it'd still be useful if we chose not to do transaction ID wraparound.
2001-08-25 20:52:43 +02:00
* Portions Copyright (c) 1994, Regents of the University of California
*
Remove cvs keywords from all files.
2010-09-20 22:08:53 +02:00
* src/include/access/clog.h
Replace implementation of pg_log as a relation accessed through the buffer manager with 'pg_clog', a specialized access method modeled on pg_xlog. This simplifies startup (don't need to play games to open pg_log; among other things, OverrideTransactionSystem goes away), should improve performance a little, and opens the door to recycling commit log space by removing no-longer-needed segments of the commit log. Actual recycling is not there yet, but I felt I should commit this part separately since it'd still be useful if we chose not to do transaction ID wraparound.
2001-08-25 20:52:43 +02:00
*/
#ifndef CLOG_H
#define CLOG_H
#include "access/xlog.h"
/*
* Possible transaction statuses --- note that all-zeroes is the initial
* state.
Nested transactions. There is still much left to do, especially on the performance front, but with feature freeze upon us I think it's time to drive a stake in the ground and say that this will be in 7.5. Alvaro Herrera, with some help from Tom Lane.
2004-07-01 02:52:04 +02:00
*
* A "subcommitted" transaction is a committed subtransaction whose parent
* hasn't committed or aborted yet.
Replace implementation of pg_log as a relation accessed through the buffer manager with 'pg_clog', a specialized access method modeled on pg_xlog. This simplifies startup (don't need to play games to open pg_log; among other things, OverrideTransactionSystem goes away), should improve performance a little, and opens the door to recycling commit log space by removing no-longer-needed segments of the commit log. Actual recycling is not there yet, but I felt I should commit this part separately since it'd still be useful if we chose not to do transaction ID wraparound.
2001-08-25 20:52:43 +02:00
*/
typedef int XidStatus;
#define TRANSACTION_STATUS_IN_PROGRESS 0x00
#define TRANSACTION_STATUS_COMMITTED 0x01
#define TRANSACTION_STATUS_ABORTED 0x02
Nested transactions. There is still much left to do, especially on the performance front, but with feature freeze upon us I think it's time to drive a stake in the ground and say that this will be in 7.5. Alvaro Herrera, with some help from Tom Lane.
2004-07-01 02:52:04 +02:00
#define TRANSACTION_STATUS_SUB_COMMITTED 0x03
Replace implementation of pg_log as a relation accessed through the buffer manager with 'pg_clog', a specialized access method modeled on pg_xlog. This simplifies startup (don't need to play games to open pg_log; among other things, OverrideTransactionSystem goes away), should improve performance a little, and opens the door to recycling commit log space by removing no-longer-needed segments of the commit log. Actual recycling is not there yet, but I felt I should commit this part separately since it'd still be useful if we chose not to do transaction ID wraparound.
2001-08-25 20:52:43 +02:00
Get rid of slru.c's hardwired insistence on a fixed number of slots per SLRU area. The number of slots is still a compile-time constant (someday we might want to change that), but at least it's a different constant for each SLRU area. Increase number of subtrans buffers to 32 based on experimentation with a heavily subtrans-bashing test case, and increase number of multixact member buffers to 16, since it's obviously silly for it not to be at least twice the number of multixact offset buffers.
2005-12-07 00:08:34 +01:00
/* Number of SLRU buffers to use for clog */
#define NUM_CLOG_BUFFERS 8
8.4 pgindent run, with new combined Linux/FreeBSD/MinGW typedef list provided by Andrew.
2009-06-11 16:49:15 +02:00
extern void TransactionIdSetTreeStatus(TransactionId xid, int nsubxids,
TransactionId *subxids, XidStatus status, XLogRecPtr lsn);
Support an optional asynchronous commit mode, in which we don't flush WAL before reporting a transaction committed. Data consistency is still guaranteed (unlike setting fsync = off), but a crash may lose the effects of the last few transactions. Patch by Simon, some editorialization by Tom.
2007-08-02 00:45:09 +02:00
extern XidStatus TransactionIdGetStatus(TransactionId xid, XLogRecPtr *lsn);
Replace implementation of pg_log as a relation accessed through the buffer manager with 'pg_clog', a specialized access method modeled on pg_xlog. This simplifies startup (don't need to play games to open pg_log; among other things, OverrideTransactionSystem goes away), should improve performance a little, and opens the door to recycling commit log space by removing no-longer-needed segments of the commit log. Actual recycling is not there yet, but I felt I should commit this part separately since it'd still be useful if we chose not to do transaction ID wraparound.
2001-08-25 20:52:43 +02:00
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 CLOGShmemSize(void);
Replace implementation of pg_log as a relation accessed through the buffer manager with 'pg_clog', a specialized access method modeled on pg_xlog. This simplifies startup (don't need to play games to open pg_log; among other things, OverrideTransactionSystem goes away), should improve performance a little, and opens the door to recycling commit log space by removing no-longer-needed segments of the commit log. Actual recycling is not there yet, but I felt I should commit this part separately since it'd still be useful if we chose not to do transaction ID wraparound.
2001-08-25 20:52:43 +02:00
extern void CLOGShmemInit(void);
extern void BootStrapCLOG(void);
extern void StartupCLOG(void);
extern void ShutdownCLOG(void);
extern void CheckPointCLOG(void);
extern void ExtendCLOG(TransactionId newestXact);
extern void TruncateCLOG(TransactionId oldestXact);
Rearrange pg_subtrans handling as per recent discussion. pg_subtrans updates are no longer WAL-logged nor even fsync'd; we do not need to, since after a crash no old pg_subtrans data is needed again. We truncate pg_subtrans to RecentGlobalXmin at each checkpoint. slru.c's API is refactored a little bit to separate out the necessary decisions.
2004-08-24 01:22:45 +02:00
/* XLOG stuff */
#define CLOG_ZEROPAGE 0x00
Fix recently-understood problems with handling of XID freezing, particularly in PITR scenarios. We now WAL-log the replacement of old XIDs with FrozenTransactionId, so that such replacement is guaranteed to propagate to PITR slave databases. Also, rather than relying on hint-bit updates to be preserved, pg_clog is not truncated until all instances of an XID are known to have been replaced by FrozenTransactionId. Add new GUC variables and pg_autovacuum columns to allow management of the freezing policy, so that users can trade off the size of pg_clog against the amount of freezing work done. Revise the already-existing code that forces autovacuum of tables approaching the wraparound point to make it more bulletproof; also, revise the autovacuum logic so that anti-wraparound vacuuming is done per-table rather than per-database. initdb forced because of changes in pg_class, pg_database, and pg_autovacuum catalogs. Heikki Linnakangas, Simon Riggs, and Tom Lane.
2006-11-05 23:42:10 +01:00
#define CLOG_TRUNCATE 0x10
Rearrange pg_subtrans handling as per recent discussion. pg_subtrans updates are no longer WAL-logged nor even fsync'd; we do not need to, since after a crash no old pg_subtrans data is needed again. We truncate pg_subtrans to RecentGlobalXmin at each checkpoint. slru.c's API is refactored a little bit to separate out the necessary decisions.
2004-08-24 01:22:45 +02:00
extern void clog_redo(XLogRecPtr lsn, XLogRecord *record);
Arrange to emit a description of the current XLOG record as error context when an error occurs during xlog replay. Also, replace the former risky 'write into a fixed-size buffer with no overflow detection' API for XLOG record description routines; use an expansible StringInfo instead. (The latter accounts for most of the patch bulk.) Qingqing Zhou
2006-03-24 05:32:13 +01:00
extern void clog_desc(StringInfo buf, uint8 xl_info, char *rec);
Another pgindent run. Fixes enum indenting, and improves #endif spacing. Also adds space for one-line comments.
2001-10-28 07:26:15 +01:00
New pgindent run with fixes suggested by Tom. Patch manually reviewed, initdb/regression tests pass.
2001-11-05 18:46:40 +01:00
#endif /* CLOG_H */