2001-08-25 20:52:43 +02:00
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/*
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* clog.h
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*
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* PostgreSQL transaction-commit-log manager
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*
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2017-01-03 19:48:53 +01:00
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* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
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2001-08-25 20:52:43 +02:00
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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2010-09-20 22:08:53 +02:00
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* src/include/access/clog.h
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2001-08-25 20:52:43 +02:00
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*/
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#ifndef CLOG_H
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#define CLOG_H
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Revamp the WAL record format.
Each WAL record now carries information about the modified relation and
block(s) in a standardized format. That makes it easier to write tools that
need that information, like pg_rewind, prefetching the blocks to speed up
recovery, etc.
There's a whole new API for building WAL records, replacing the XLogRecData
chains used previously. The new API consists of XLogRegister* functions,
which are called for each buffer and chunk of data that is added to the
record. The new API also gives more control over when a full-page image is
written, by passing flags to the XLogRegisterBuffer function.
This also simplifies the XLogReadBufferForRedo() calls. The function can dig
the relation and block number from the WAL record, so they no longer need to
be passed as arguments.
For the convenience of redo routines, XLogReader now disects each WAL record
after reading it, copying the main data part and the per-block data into
MAXALIGNed buffers. The data chunks are not aligned within the WAL record,
but the redo routines can assume that the pointers returned by XLogRecGet*
functions are. Redo routines are now passed the XLogReaderState, which
contains the record in the already-disected format, instead of the plain
XLogRecord.
The new record format also makes the fixed size XLogRecord header smaller,
by removing the xl_len field. The length of the "main data" portion is now
stored at the end of the WAL record, and there's a separate header after
XLogRecord for it. The alignment padding at the end of XLogRecord is also
removed. This compansates for the fact that the new format would otherwise
be more bulky than the old format.
Reviewed by Andres Freund, Amit Kapila, Michael Paquier, Alvaro Herrera,
Fujii Masao.
2014-11-20 16:56:26 +01:00
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#include "access/xlogreader.h"
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2014-11-06 12:52:08 +01:00
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#include "lib/stringinfo.h"
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2001-08-25 20:52:43 +02:00
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/*
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* Possible transaction statuses --- note that all-zeroes is the initial
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* state.
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2004-07-01 02:52:04 +02:00
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*
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* A "subcommitted" transaction is a committed subtransaction whose parent
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* hasn't committed or aborted yet.
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2001-08-25 20:52:43 +02:00
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*/
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typedef int XidStatus;
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#define TRANSACTION_STATUS_IN_PROGRESS 0x00
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#define TRANSACTION_STATUS_COMMITTED 0x01
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#define TRANSACTION_STATUS_ABORTED 0x02
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2004-07-01 02:52:04 +02:00
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#define TRANSACTION_STATUS_SUB_COMMITTED 0x03
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2001-08-25 20:52:43 +02:00
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2017-03-23 19:08:23 +01:00
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typedef struct xl_clog_truncate
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{
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2017-05-17 22:31:56 +02:00
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int pageno;
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2017-03-23 19:08:23 +01:00
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TransactionId oldestXact;
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2017-05-17 22:31:56 +02:00
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Oid oldestXactDb;
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2017-03-23 19:08:23 +01:00
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} xl_clog_truncate;
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2001-08-25 20:52:43 +02:00
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2009-06-11 16:49:15 +02:00
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extern void TransactionIdSetTreeStatus(TransactionId xid, int nsubxids,
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TransactionId *subxids, XidStatus status, XLogRecPtr lsn);
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2007-08-02 00:45:09 +02:00
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extern XidStatus TransactionIdGetStatus(TransactionId xid, XLogRecPtr *lsn);
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2001-08-25 20:52:43 +02:00
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2012-01-06 20:30:23 +01:00
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extern Size CLOGShmemBuffers(void);
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2005-08-21 01:26:37 +02:00
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extern Size CLOGShmemSize(void);
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2001-08-25 20:52:43 +02:00
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extern void CLOGShmemInit(void);
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extern void BootStrapCLOG(void);
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extern void StartupCLOG(void);
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2011-11-02 09:07:44 +01:00
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extern void TrimCLOG(void);
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2001-08-25 20:52:43 +02:00
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extern void ShutdownCLOG(void);
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extern void CheckPointCLOG(void);
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extern void ExtendCLOG(TransactionId newestXact);
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2017-03-23 19:08:23 +01:00
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extern void TruncateCLOG(TransactionId oldestXact, Oid oldestxid_datoid);
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2004-08-24 01:22:45 +02:00
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/* XLOG stuff */
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#define CLOG_ZEROPAGE 0x00
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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
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#define CLOG_TRUNCATE 0x10
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2004-08-24 01:22:45 +02:00
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Revamp the WAL record format.
Each WAL record now carries information about the modified relation and
block(s) in a standardized format. That makes it easier to write tools that
need that information, like pg_rewind, prefetching the blocks to speed up
recovery, etc.
There's a whole new API for building WAL records, replacing the XLogRecData
chains used previously. The new API consists of XLogRegister* functions,
which are called for each buffer and chunk of data that is added to the
record. The new API also gives more control over when a full-page image is
written, by passing flags to the XLogRegisterBuffer function.
This also simplifies the XLogReadBufferForRedo() calls. The function can dig
the relation and block number from the WAL record, so they no longer need to
be passed as arguments.
For the convenience of redo routines, XLogReader now disects each WAL record
after reading it, copying the main data part and the per-block data into
MAXALIGNed buffers. The data chunks are not aligned within the WAL record,
but the redo routines can assume that the pointers returned by XLogRecGet*
functions are. Redo routines are now passed the XLogReaderState, which
contains the record in the already-disected format, instead of the plain
XLogRecord.
The new record format also makes the fixed size XLogRecord header smaller,
by removing the xl_len field. The length of the "main data" portion is now
stored at the end of the WAL record, and there's a separate header after
XLogRecord for it. The alignment padding at the end of XLogRecord is also
removed. This compansates for the fact that the new format would otherwise
be more bulky than the old format.
Reviewed by Andres Freund, Amit Kapila, Michael Paquier, Alvaro Herrera,
Fujii Masao.
2014-11-20 16:56:26 +01:00
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extern void clog_redo(XLogReaderState *record);
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extern void clog_desc(StringInfo buf, XLogReaderState *record);
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2014-09-19 15:17:12 +02:00
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extern const char *clog_identify(uint8 info);
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2001-10-28 07:26:15 +01:00
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2001-11-05 18:46:40 +01:00
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#endif /* CLOG_H */
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