commit_ts.h File Reference

#include "access/xlog.h"
#include "datatype/timestamp.h"
#include "replication/origin.h"
#include "storage/sync.h"

Include dependency graph for commit_ts.h:

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Go to the source code of this file.

Data Structures
struct	xl_commit_ts_set
struct	xl_commit_ts_truncate

Macros
#define	COMMIT_TS_ZEROPAGE   0x00
#define	COMMIT_TS_TRUNCATE   0x10
#define	SizeOfCommitTsSet
#define	SizeOfCommitTsTruncate

Typedefs
typedef struct xl_commit_ts_set	xl_commit_ts_set
typedef struct xl_commit_ts_truncate	xl_commit_ts_truncate

Functions
void	TransactionTreeSetCommitTsData (TransactionId xid, int nsubxids, TransactionId *subxids, TimestampTz timestamp, RepOriginId nodeid)
bool	TransactionIdGetCommitTsData (TransactionId xid, TimestampTz *ts, RepOriginId *nodeid)
TransactionId	GetLatestCommitTsData (TimestampTz *ts, RepOriginId *nodeid)
Size	CommitTsShmemSize (void)
void	CommitTsShmemInit (void)
void	BootStrapCommitTs (void)
void	StartupCommitTs (void)
void	CommitTsParameterChange (bool newvalue, bool oldvalue)
void	CompleteCommitTsInitialization (void)
void	CheckPointCommitTs (void)
void	ExtendCommitTs (TransactionId newestXact)
void	TruncateCommitTs (TransactionId oldestXact)
void	SetCommitTsLimit (TransactionId oldestXact, TransactionId newestXact)
void	AdvanceOldestCommitTsXid (TransactionId oldestXact)
int	committssyncfiletag (const FileTag *ftag, char *path)
void	commit_ts_redo (XLogReaderState *record)
void	commit_ts_desc (StringInfo buf, XLogReaderState *record)
const char *	commit_ts_identify (uint8 info)

Variables
PGDLLIMPORT bool	track_commit_timestamp

Macro Definition Documentation

COMMIT_TS_TRUNCATE

#define COMMIT_TS_TRUNCATE   0x10

Definition at line 47 of file commit_ts.h.

COMMIT_TS_ZEROPAGE

#define COMMIT_TS_ZEROPAGE   0x00

Definition at line 46 of file commit_ts.h.

SizeOfCommitTsSet

#define SizeOfCommitTsSet

Value:

                             (offsetof(xl_commit_ts_set, mainxid) + \
                             sizeof(TransactionId))

Definition at line 57 of file commit_ts.h.

SizeOfCommitTsTruncate

#define SizeOfCommitTsTruncate

Value:

                                 (offsetof(xl_commit_ts_truncate, oldestXid) + \
                                 sizeof(TransactionId))

Definition at line 66 of file commit_ts.h.

Typedef Documentation

xl_commit_ts_set

typedef struct xl_commit_ts_set xl_commit_ts_set

xl_commit_ts_truncate

typedef struct xl_commit_ts_truncate xl_commit_ts_truncate

Function Documentation

AdvanceOldestCommitTsXid()

void AdvanceOldestCommitTsXid

(

TransactionId

oldestXact

)

Definition at line 936 of file commit_ts.c.

{
    LWLockAcquire(CommitTsLock, LW_EXCLUSIVE);
    if (TransamVariables->oldestCommitTsXid != InvalidTransactionId &&
        TransactionIdPrecedes(TransamVariables->oldestCommitTsXid, oldestXact))
        TransamVariables->oldestCommitTsXid = oldestXact;
    LWLockRelease(CommitTsLock);
}

References InvalidTransactionId, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), TransamVariablesData::oldestCommitTsXid, TransactionIdPrecedes(), and TransamVariables.

Referenced by commit_ts_redo(), and vac_truncate_clog().

BootStrapCommitTs()

void BootStrapCommitTs

(

void

)

Definition at line 596 of file commit_ts.c.

{
    /*
     * Nothing to do here at present, unlike most other SLRU modules; segments
     * are created when the server is started with this module enabled. See
     * ActivateCommitTs.
     */
}

Referenced by BootStrapXLOG().

CheckPointCommitTs()

void CheckPointCommitTs

(

void

)

Definition at line 820 of file commit_ts.c.

{
    /*
     * Write dirty CommitTs pages to disk.  This may result in sync requests
     * queued for later handling by ProcessSyncRequests(), as part of the
     * checkpoint.
     */
    SimpleLruWriteAll(CommitTsCtl, true);
}

References CommitTsCtl, and SimpleLruWriteAll().

Referenced by CheckPointGuts().

commit_ts_desc()

void commit_ts_desc	(	StringInfo	buf,
		XLogReaderState *	record
	)

Definition at line 21 of file committsdesc.c.

{
    char       *rec = XLogRecGetData(record);
    uint8       info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
 
    if (info == COMMIT_TS_ZEROPAGE)
    {
        int64       pageno;
 
        memcpy(&pageno, rec, sizeof(pageno));
        appendStringInfo(buf, "%" PRId64, pageno);
    }
    else if (info == COMMIT_TS_TRUNCATE)
    {
        xl_commit_ts_truncate *trunc = (xl_commit_ts_truncate *) rec;
 
        appendStringInfo(buf, "pageno %" PRId64 ", oldestXid %u",
                         trunc->pageno, trunc->oldestXid);
    }
}

References appendStringInfo(), buf, COMMIT_TS_TRUNCATE, COMMIT_TS_ZEROPAGE, xl_commit_ts_truncate::oldestXid, xl_commit_ts_truncate::pageno, XLogRecGetData, and XLogRecGetInfo.

commit_ts_identify()

const char * commit_ts_identify

(

uint8

info

)

Definition at line 43 of file committsdesc.c.

{
    switch (info)
    {
        case COMMIT_TS_ZEROPAGE:
            return "ZEROPAGE";
        case COMMIT_TS_TRUNCATE:
            return "TRUNCATE";
        default:
            return NULL;
    }
}

References COMMIT_TS_TRUNCATE, and COMMIT_TS_ZEROPAGE.

commit_ts_redo()

void commit_ts_redo

(

XLogReaderState *

record

)

Definition at line 1016 of file commit_ts.c.

{
    uint8       info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
 
    /* Backup blocks are not used in commit_ts records */
    Assert(!XLogRecHasAnyBlockRefs(record));
 
    if (info == COMMIT_TS_ZEROPAGE)
    {
        int64       pageno;
        int         slotno;
        LWLock     *lock;
 
        memcpy(&pageno, XLogRecGetData(record), sizeof(pageno));
 
        lock = SimpleLruGetBankLock(CommitTsCtl, pageno);
        LWLockAcquire(lock, LW_EXCLUSIVE);
 
        slotno = ZeroCommitTsPage(pageno, false);
        SimpleLruWritePage(CommitTsCtl, slotno);
        Assert(!CommitTsCtl->shared->page_dirty[slotno]);
 
        LWLockRelease(lock);
    }
    else if (info == COMMIT_TS_TRUNCATE)
    {
        xl_commit_ts_truncate *trunc = (xl_commit_ts_truncate *) XLogRecGetData(record);
 
        AdvanceOldestCommitTsXid(trunc->oldestXid);
 
        /*
         * During XLOG replay, latest_page_number isn't set up yet; insert a
         * suitable value to bypass the sanity test in SimpleLruTruncate.
         */
        pg_atomic_write_u64(&CommitTsCtl->shared->latest_page_number,
                            trunc->pageno);
 
        SimpleLruTruncate(CommitTsCtl, trunc->pageno);
    }
    else
        elog(PANIC, "commit_ts_redo: unknown op code %u", info);
}

References AdvanceOldestCommitTsXid(), Assert(), COMMIT_TS_TRUNCATE, COMMIT_TS_ZEROPAGE, CommitTsCtl, elog, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), xl_commit_ts_truncate::oldestXid, xl_commit_ts_truncate::pageno, PANIC, pg_atomic_write_u64(), SimpleLruGetBankLock(), SimpleLruTruncate(), SimpleLruWritePage(), XLogRecGetData, XLogRecGetInfo, XLogRecHasAnyBlockRefs, and ZeroCommitTsPage().

CommitTsParameterChange()

void CommitTsParameterChange	(	bool	newvalue,
		bool	oldvalue
	)

Definition at line 664 of file commit_ts.c.

{
    /*
     * If the commit_ts module is disabled in this server and we get word from
     * the primary server that it is enabled there, activate it so that we can
     * replay future WAL records involving it; also mark it as active on
     * pg_control.  If the old value was already set, we already did this, so
     * don't do anything.
     *
     * If the module is disabled in the primary, disable it here too, unless
     * the module is enabled locally.
     *
     * Note this only runs in the recovery process, so an unlocked read is
     * fine.
     */
    if (newvalue)
    {
        if (!commitTsShared->commitTsActive)
            ActivateCommitTs();
    }
    else if (commitTsShared->commitTsActive)
        DeactivateCommitTs();
}

References ActivateCommitTs(), CommitTimestampShared::commitTsActive, commitTsShared, and DeactivateCommitTs().

Referenced by xlog_redo().

CommitTsShmemInit()

void CommitTsShmemInit

(

void

)

Definition at line 530 of file commit_ts.c.

{
    bool        found;
 
    /* If auto-tuning is requested, now is the time to do it */
    if (commit_timestamp_buffers == 0)
    {
        char        buf[32];
 
        snprintf(buf, sizeof(buf), "%d", CommitTsShmemBuffers());
        SetConfigOption("commit_timestamp_buffers", buf, PGC_POSTMASTER,
                        PGC_S_DYNAMIC_DEFAULT);
 
        /*
         * We prefer to report this value's source as PGC_S_DYNAMIC_DEFAULT.
         * However, if the DBA explicitly set commit_timestamp_buffers = 0 in
         * the config file, then PGC_S_DYNAMIC_DEFAULT will fail to override
         * that and we must force the matter with PGC_S_OVERRIDE.
         */
        if (commit_timestamp_buffers == 0)  /* failed to apply it? */
            SetConfigOption("commit_timestamp_buffers", buf, PGC_POSTMASTER,
                            PGC_S_OVERRIDE);
    }
    Assert(commit_timestamp_buffers != 0);
 
    CommitTsCtl->PagePrecedes = CommitTsPagePrecedes;
    SimpleLruInit(CommitTsCtl, "commit_timestamp", CommitTsShmemBuffers(), 0,
                  "pg_commit_ts", LWTRANCHE_COMMITTS_BUFFER,
                  LWTRANCHE_COMMITTS_SLRU,
                  SYNC_HANDLER_COMMIT_TS,
                  false);
    SlruPagePrecedesUnitTests(CommitTsCtl, COMMIT_TS_XACTS_PER_PAGE);
 
    commitTsShared = ShmemInitStruct("CommitTs shared",
                                     sizeof(CommitTimestampShared),
                                     &found);
 
    if (!IsUnderPostmaster)
    {
        Assert(!found);
 
        commitTsShared->xidLastCommit = InvalidTransactionId;
        TIMESTAMP_NOBEGIN(commitTsShared->dataLastCommit.time);
        commitTsShared->dataLastCommit.nodeid = InvalidRepOriginId;
        commitTsShared->commitTsActive = false;
    }
    else
        Assert(found);
}

References Assert(), buf, commit_timestamp_buffers, COMMIT_TS_XACTS_PER_PAGE, CommitTimestampShared::commitTsActive, CommitTsCtl, CommitTsPagePrecedes(), commitTsShared, CommitTsShmemBuffers(), CommitTimestampShared::dataLastCommit, InvalidRepOriginId, InvalidTransactionId, IsUnderPostmaster, LWTRANCHE_COMMITTS_BUFFER, LWTRANCHE_COMMITTS_SLRU, CommitTimestampEntry::nodeid, PGC_POSTMASTER, PGC_S_DYNAMIC_DEFAULT, PGC_S_OVERRIDE, SetConfigOption(), ShmemInitStruct(), SimpleLruInit(), SlruPagePrecedesUnitTests, snprintf, SYNC_HANDLER_COMMIT_TS, CommitTimestampEntry::time, TIMESTAMP_NOBEGIN, and CommitTimestampShared::xidLastCommit.

Referenced by CreateOrAttachShmemStructs().

CommitTsShmemSize()

Size CommitTsShmemSize

(

void

)

Definition at line 519 of file commit_ts.c.

{
    return SimpleLruShmemSize(CommitTsShmemBuffers(), 0) +
        sizeof(CommitTimestampShared);
}

References CommitTsShmemBuffers(), and SimpleLruShmemSize().

Referenced by CalculateShmemSize().

committssyncfiletag()

int committssyncfiletag	(	const FileTag *	ftag,
		char *	path
	)

Definition at line 1063 of file commit_ts.c.

{
    return SlruSyncFileTag(CommitTsCtl, ftag, path);
}

References CommitTsCtl, and SlruSyncFileTag().

CompleteCommitTsInitialization()

void CompleteCommitTsInitialization

(

void

)

Definition at line 642 of file commit_ts.c.

{
    /*
     * If the feature is not enabled, turn it off for good.  This also removes
     * any leftover data.
     *
     * Conversely, we activate the module if the feature is enabled.  This is
     * necessary for primary and standby as the activation depends on the
     * control file contents at the beginning of recovery or when a
     * XLOG_PARAMETER_CHANGE is replayed.
     */
    if (!track_commit_timestamp)
        DeactivateCommitTs();
    else
        ActivateCommitTs();
}

References ActivateCommitTs(), DeactivateCommitTs(), and track_commit_timestamp.

Referenced by StartupXLOG().

ExtendCommitTs()

void ExtendCommitTs

(

TransactionId

newestXact

)

Definition at line 842 of file commit_ts.c.

{
    int64       pageno;
    LWLock     *lock;
 
    /*
     * Nothing to do if module not enabled.  Note we do an unlocked read of
     * the flag here, which is okay because this routine is only called from
     * GetNewTransactionId, which is never called in a standby.
     */
    Assert(!InRecovery);
    if (!commitTsShared->commitTsActive)
        return;
 
    /*
     * No work except at first XID of a page.  But beware: just after
     * wraparound, the first XID of page zero is FirstNormalTransactionId.
     */
    if (TransactionIdToCTsEntry(newestXact) != 0 &&
        !TransactionIdEquals(newestXact, FirstNormalTransactionId))
        return;
 
    pageno = TransactionIdToCTsPage(newestXact);
 
    lock = SimpleLruGetBankLock(CommitTsCtl, pageno);
 
    LWLockAcquire(lock, LW_EXCLUSIVE);
 
    /* Zero the page and make an XLOG entry about it */
    ZeroCommitTsPage(pageno, !InRecovery);
 
    LWLockRelease(lock);
}

References Assert(), CommitTimestampShared::commitTsActive, CommitTsCtl, commitTsShared, FirstNormalTransactionId, InRecovery, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), SimpleLruGetBankLock(), TransactionIdEquals, TransactionIdToCTsEntry, TransactionIdToCTsPage(), and ZeroCommitTsPage().

Referenced by GetNewTransactionId().

GetLatestCommitTsData()

TransactionId GetLatestCommitTsData	(	TimestampTz *	ts,
		RepOriginId *	nodeid
	)

Definition at line 360 of file commit_ts.c.

{
    TransactionId xid;
 
    LWLockAcquire(CommitTsLock, LW_SHARED);
 
    /* Error if module not enabled */
    if (!commitTsShared->commitTsActive)
        error_commit_ts_disabled();
 
    xid = commitTsShared->xidLastCommit;
    if (ts)
        *ts = commitTsShared->dataLastCommit.time;
    if (nodeid)
        *nodeid = commitTsShared->dataLastCommit.nodeid;
    LWLockRelease(CommitTsLock);
 
    return xid;
}

References CommitTimestampShared::commitTsActive, commitTsShared, CommitTimestampShared::dataLastCommit, error_commit_ts_disabled(), LW_SHARED, LWLockAcquire(), LWLockRelease(), CommitTimestampEntry::nodeid, CommitTimestampEntry::time, and CommitTimestampShared::xidLastCommit.

Referenced by pg_last_committed_xact().

SetCommitTsLimit()

void SetCommitTsLimit	(	TransactionId	oldestXact,
		TransactionId	newestXact
	)

Definition at line 909 of file commit_ts.c.

{
    /*
     * Be careful not to overwrite values that are either further into the
     * "future" or signal a disabled committs.
     */
    LWLockAcquire(CommitTsLock, LW_EXCLUSIVE);
    if (TransamVariables->oldestCommitTsXid != InvalidTransactionId)
    {
        if (TransactionIdPrecedes(TransamVariables->oldestCommitTsXid, oldestXact))
            TransamVariables->oldestCommitTsXid = oldestXact;
        if (TransactionIdPrecedes(newestXact, TransamVariables->newestCommitTsXid))
            TransamVariables->newestCommitTsXid = newestXact;
    }
    else
    {
        Assert(TransamVariables->newestCommitTsXid == InvalidTransactionId);
        TransamVariables->oldestCommitTsXid = oldestXact;
        TransamVariables->newestCommitTsXid = newestXact;
    }
    LWLockRelease(CommitTsLock);
}

References Assert(), InvalidTransactionId, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), TransamVariablesData::newestCommitTsXid, TransamVariablesData::oldestCommitTsXid, TransactionIdPrecedes(), and TransamVariables.

Referenced by BootStrapXLOG(), and StartupXLOG().

StartupCommitTs()

void StartupCommitTs

(

void

)

Definition at line 632 of file commit_ts.c.

{
    ActivateCommitTs();
}

References ActivateCommitTs().

Referenced by StartupXLOG().

TransactionIdGetCommitTsData()

bool TransactionIdGetCommitTsData	(	TransactionId	xid,
		TimestampTz *	ts,
		RepOriginId *	nodeid
	)

Definition at line 274 of file commit_ts.c.

{
    int64       pageno = TransactionIdToCTsPage(xid);
    int         entryno = TransactionIdToCTsEntry(xid);
    int         slotno;
    CommitTimestampEntry entry;
    TransactionId oldestCommitTsXid;
    TransactionId newestCommitTsXid;
 
    if (!TransactionIdIsValid(xid))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("cannot retrieve commit timestamp for transaction %u", xid)));
    else if (!TransactionIdIsNormal(xid))
    {
        /* frozen and bootstrap xids are always committed far in the past */
        *ts = 0;
        if (nodeid)
            *nodeid = 0;
        return false;
    }
 
    LWLockAcquire(CommitTsLock, LW_SHARED);
 
    /* Error if module not enabled */
    if (!commitTsShared->commitTsActive)
        error_commit_ts_disabled();
 
    /*
     * If we're asked for the cached value, return that.  Otherwise, fall
     * through to read from SLRU.
     */
    if (commitTsShared->xidLastCommit == xid)
    {
        *ts = commitTsShared->dataLastCommit.time;
        if (nodeid)
            *nodeid = commitTsShared->dataLastCommit.nodeid;
 
        LWLockRelease(CommitTsLock);
        return *ts != 0;
    }
 
    oldestCommitTsXid = TransamVariables->oldestCommitTsXid;
    newestCommitTsXid = TransamVariables->newestCommitTsXid;
    /* neither is invalid, or both are */
    Assert(TransactionIdIsValid(oldestCommitTsXid) == TransactionIdIsValid(newestCommitTsXid));
    LWLockRelease(CommitTsLock);
 
    /*
     * Return empty if the requested value is outside our valid range.
     */
    if (!TransactionIdIsValid(oldestCommitTsXid) ||
        TransactionIdPrecedes(xid, oldestCommitTsXid) ||
        TransactionIdPrecedes(newestCommitTsXid, xid))
    {
        *ts = 0;
        if (nodeid)
            *nodeid = InvalidRepOriginId;
        return false;
    }
 
    /* lock is acquired by SimpleLruReadPage_ReadOnly */
    slotno = SimpleLruReadPage_ReadOnly(CommitTsCtl, pageno, xid);
    memcpy(&entry,
           CommitTsCtl->shared->page_buffer[slotno] +
           SizeOfCommitTimestampEntry * entryno,
           SizeOfCommitTimestampEntry);
 
    *ts = entry.time;
    if (nodeid)
        *nodeid = entry.nodeid;
 
    LWLockRelease(SimpleLruGetBankLock(CommitTsCtl, pageno));
    return *ts != 0;
}

References Assert(), CommitTimestampShared::commitTsActive, CommitTsCtl, commitTsShared, CommitTimestampShared::dataLastCommit, ereport, errcode(), errmsg(), ERROR, error_commit_ts_disabled(), InvalidRepOriginId, LW_SHARED, LWLockAcquire(), LWLockRelease(), TransamVariablesData::newestCommitTsXid, CommitTimestampEntry::nodeid, TransamVariablesData::oldestCommitTsXid, SimpleLruGetBankLock(), SimpleLruReadPage_ReadOnly(), SizeOfCommitTimestampEntry, CommitTimestampEntry::time, TransactionIdIsNormal, TransactionIdIsValid, TransactionIdPrecedes(), TransactionIdToCTsEntry, TransactionIdToCTsPage(), TransamVariables, and CommitTimestampShared::xidLastCommit.

Referenced by GetTupleTransactionInfo(), pg_xact_commit_timestamp(), and pg_xact_commit_timestamp_origin().

TransactionTreeSetCommitTsData()

void TransactionTreeSetCommitTsData	(	TransactionId	xid,
		int	nsubxids,
		TransactionId *	subxids,
		TimestampTz	timestamp,
		RepOriginId	nodeid
	)

Definition at line 141 of file commit_ts.c.

{
    int         i;
    TransactionId headxid;
    TransactionId newestXact;
 
    /*
     * No-op if the module is not active.
     *
     * An unlocked read here is fine, because in a standby (the only place
     * where the flag can change in flight) this routine is only called by the
     * recovery process, which is also the only process which can change the
     * flag.
     */
    if (!commitTsShared->commitTsActive)
        return;
 
    /*
     * Figure out the latest Xid in this batch: either the last subxid if
     * there's any, otherwise the parent xid.
     */
    if (nsubxids > 0)
        newestXact = subxids[nsubxids - 1];
    else
        newestXact = xid;
 
    /*
     * We split the xids to set the timestamp to in groups belonging to the
     * same SLRU page; the first element in each such set is its head.  The
     * first group has the main XID as the head; subsequent sets use the first
     * subxid not on the previous page as head.  This way, we only have to
     * lock/modify each SLRU page once.
     */
    headxid = xid;
    i = 0;
    for (;;)
    {
        int64       pageno = TransactionIdToCTsPage(headxid);
        int         j;
 
        for (j = i; j < nsubxids; j++)
        {
            if (TransactionIdToCTsPage(subxids[j]) != pageno)
                break;
        }
        /* subxids[i..j] are on the same page as the head */
 
        SetXidCommitTsInPage(headxid, j - i, subxids + i, timestamp, nodeid,
                             pageno);
 
        /* if we wrote out all subxids, we're done. */
        if (j >= nsubxids)
            break;
 
        /*
         * Set the new head and skip over it, as well as over the subxids we
         * just wrote.
         */
        headxid = subxids[j];
        i = j + 1;
    }
 
    /* update the cached value in shared memory */
    LWLockAcquire(CommitTsLock, LW_EXCLUSIVE);
    commitTsShared->xidLastCommit = xid;
    commitTsShared->dataLastCommit.time = timestamp;
    commitTsShared->dataLastCommit.nodeid = nodeid;
 
    /* and move forwards our endpoint, if needed */
    if (TransactionIdPrecedes(TransamVariables->newestCommitTsXid, newestXact))
        TransamVariables->newestCommitTsXid = newestXact;
    LWLockRelease(CommitTsLock);
}

References CommitTimestampShared::commitTsActive, commitTsShared, CommitTimestampShared::dataLastCommit, i, j, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), TransamVariablesData::newestCommitTsXid, CommitTimestampEntry::nodeid, SetXidCommitTsInPage(), CommitTimestampEntry::time, TransactionIdPrecedes(), TransactionIdToCTsPage(), TransamVariables, and CommitTimestampShared::xidLastCommit.

Referenced by RecordTransactionCommit(), RecordTransactionCommitPrepared(), and xact_redo_commit().

TruncateCommitTs()

void TruncateCommitTs

(

TransactionId

oldestXact

)

Definition at line 883 of file commit_ts.c.

{
    int64       cutoffPage;
 
    /*
     * The cutoff point is the start of the segment containing oldestXact. We
     * pass the *page* containing oldestXact to SimpleLruTruncate.
     */
    cutoffPage = TransactionIdToCTsPage(oldestXact);
 
    /* Check to see if there's any files that could be removed */
    if (!SlruScanDirectory(CommitTsCtl, SlruScanDirCbReportPresence,
                           &cutoffPage))
        return;                 /* nothing to remove */
 
    /* Write XLOG record */
    WriteTruncateXlogRec(cutoffPage, oldestXact);
 
    /* Now we can remove the old CommitTs segment(s) */
    SimpleLruTruncate(CommitTsCtl, cutoffPage);
}

References CommitTsCtl, SimpleLruTruncate(), SlruScanDirCbReportPresence(), SlruScanDirectory(), TransactionIdToCTsPage(), and WriteTruncateXlogRec().

Referenced by vac_truncate_clog().

Variable Documentation

track_commit_timestamp

PGDLLIMPORT bool track_commit_timestamp

extern

Definition at line 109 of file commit_ts.c.

Referenced by CompleteCommitTsInitialization(), GetTupleTransactionInfo(), InitControlFile(), and XLogReportParameters().