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clog.h File Reference
#include "access/xlogreader.h"
#include "lib/stringinfo.h"
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Data Structures

struct  xl_clog_truncate
 

Macros

#define TRANSACTION_STATUS_IN_PROGRESS   0x00
 
#define TRANSACTION_STATUS_COMMITTED   0x01
 
#define TRANSACTION_STATUS_ABORTED   0x02
 
#define TRANSACTION_STATUS_SUB_COMMITTED   0x03
 
#define CLOG_ZEROPAGE   0x00
 
#define CLOG_TRUNCATE   0x10
 

Typedefs

typedef int XidStatus
 
typedef struct xl_clog_truncate xl_clog_truncate
 

Functions

void TransactionIdSetTreeStatus (TransactionId xid, int nsubxids, TransactionId *subxids, XidStatus status, XLogRecPtr lsn)
 
XidStatus TransactionIdGetStatus (TransactionId xid, XLogRecPtr *lsn)
 
Size CLOGShmemBuffers (void)
 
Size CLOGShmemSize (void)
 
void CLOGShmemInit (void)
 
void BootStrapCLOG (void)
 
void StartupCLOG (void)
 
void TrimCLOG (void)
 
void ShutdownCLOG (void)
 
void CheckPointCLOG (void)
 
void ExtendCLOG (TransactionId newestXact)
 
void TruncateCLOG (TransactionId oldestXact, Oid oldestxid_datoid)
 
void clog_redo (XLogReaderState *record)
 
void clog_desc (StringInfo buf, XLogReaderState *record)
 
const char * clog_identify (uint8 info)
 

Macro Definition Documentation

#define CLOG_TRUNCATE   0x10

Definition at line 55 of file clog.h.

Referenced by clog_desc(), clog_identify(), clog_redo(), and WriteTruncateXlogRec().

#define CLOG_ZEROPAGE   0x00

Definition at line 54 of file clog.h.

Referenced by clog_desc(), clog_identify(), clog_redo(), and WriteZeroPageXlogRec().

#define TRANSACTION_STATUS_ABORTED   0x02
#define TRANSACTION_STATUS_IN_PROGRESS   0x00

Definition at line 26 of file clog.h.

Referenced by TransactionIdSetStatusBit(), and TransactionLogFetch().

#define TRANSACTION_STATUS_SUB_COMMITTED   0x03

Typedef Documentation

Definition at line 24 of file clog.h.

Function Documentation

void BootStrapCLOG ( void  )

Definition at line 464 of file clog.c.

References Assert, ClogCtl, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), SimpleLruWritePage(), and ZeroCLOGPage().

Referenced by BootStrapXLOG().

465 {
466  int slotno;
467 
468  LWLockAcquire(CLogControlLock, LW_EXCLUSIVE);
469 
470  /* Create and zero the first page of the commit log */
471  slotno = ZeroCLOGPage(0, false);
472 
473  /* Make sure it's written out */
474  SimpleLruWritePage(ClogCtl, slotno);
475  Assert(!ClogCtl->shared->page_dirty[slotno]);
476 
477  LWLockRelease(CLogControlLock);
478 }
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
#define ClogCtl
Definition: clog.c:80
void SimpleLruWritePage(SlruCtl ctl, int slotno)
Definition: slru.c:578
#define Assert(condition)
Definition: c.h:676
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1111
static int ZeroCLOGPage(int pageno, bool writeXlog)
Definition: clog.c:490
void CheckPointCLOG ( void  )

Definition at line 594 of file clog.c.

References ClogCtl, fsync_fname(), and SimpleLruFlush().

Referenced by CheckPointGuts().

595 {
596  /* Flush dirty CLOG pages to disk */
597  TRACE_POSTGRESQL_CLOG_CHECKPOINT_START(true);
598  SimpleLruFlush(ClogCtl, true);
599 
600  /*
601  * fsync pg_xact to ensure that any files flushed previously are durably
602  * on disk.
603  */
604  fsync_fname("pg_xact", true);
605 
606  TRACE_POSTGRESQL_CLOG_CHECKPOINT_DONE(true);
607 }
void fsync_fname(const char *fname, bool isdir)
Definition: fd.c:567
void SimpleLruFlush(SlruCtl ctl, bool allow_redirtied)
Definition: slru.c:1104
#define ClogCtl
Definition: clog.c:80
void clog_desc ( StringInfo  buf,
XLogReaderState record 
)

Definition at line 21 of file clogdesc.c.

References appendStringInfo(), CLOG_TRUNCATE, CLOG_ZEROPAGE, xl_clog_truncate::oldestXact, xl_clog_truncate::pageno, XLogRecGetData, XLogRecGetInfo, and XLR_INFO_MASK.

22 {
23  char *rec = XLogRecGetData(record);
24  uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
25 
26  if (info == CLOG_ZEROPAGE)
27  {
28  int pageno;
29 
30  memcpy(&pageno, rec, sizeof(int));
31  appendStringInfo(buf, "page %d", pageno);
32  }
33  else if (info == CLOG_TRUNCATE)
34  {
35  xl_clog_truncate xlrec;
36 
37  memcpy(&xlrec, rec, sizeof(xl_clog_truncate));
38  appendStringInfo(buf, "page %d; oldestXact %u",
39  xlrec.pageno, xlrec.oldestXact);
40  }
41 }
unsigned char uint8
Definition: c.h:266
#define CLOG_ZEROPAGE
Definition: clog.h:54
#define XLogRecGetData(decoder)
Definition: xlogreader.h:220
void appendStringInfo(StringInfo str, const char *fmt,...)
Definition: stringinfo.c:78
int pageno
Definition: clog.h:33
#define CLOG_TRUNCATE
Definition: clog.h:55
#define XLogRecGetInfo(decoder)
Definition: xlogreader.h:216
TransactionId oldestXact
Definition: clog.h:34
#define XLR_INFO_MASK
Definition: xlogrecord.h:62
const char* clog_identify ( uint8  info)

Definition at line 44 of file clogdesc.c.

References CLOG_TRUNCATE, CLOG_ZEROPAGE, NULL, and XLR_INFO_MASK.

45 {
46  const char *id = NULL;
47 
48  switch (info & ~XLR_INFO_MASK)
49  {
50  case CLOG_ZEROPAGE:
51  id = "ZEROPAGE";
52  break;
53  case CLOG_TRUNCATE:
54  id = "TRUNCATE";
55  break;
56  }
57 
58  return id;
59 }
#define CLOG_ZEROPAGE
Definition: clog.h:54
#define CLOG_TRUNCATE
Definition: clog.h:55
#define NULL
Definition: c.h:229
#define XLR_INFO_MASK
Definition: xlogrecord.h:62
void clog_redo ( XLogReaderState record)

Definition at line 755 of file clog.c.

References AdvanceOldestClogXid(), Assert, CLOG_TRUNCATE, CLOG_ZEROPAGE, ClogCtl, elog, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), xl_clog_truncate::oldestXact, xl_clog_truncate::pageno, PANIC, SimpleLruTruncate(), SimpleLruWritePage(), XLogRecGetData, XLogRecGetInfo, XLogRecHasAnyBlockRefs, XLR_INFO_MASK, and ZeroCLOGPage().

756 {
757  uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
758 
759  /* Backup blocks are not used in clog records */
760  Assert(!XLogRecHasAnyBlockRefs(record));
761 
762  if (info == CLOG_ZEROPAGE)
763  {
764  int pageno;
765  int slotno;
766 
767  memcpy(&pageno, XLogRecGetData(record), sizeof(int));
768 
769  LWLockAcquire(CLogControlLock, LW_EXCLUSIVE);
770 
771  slotno = ZeroCLOGPage(pageno, false);
772  SimpleLruWritePage(ClogCtl, slotno);
773  Assert(!ClogCtl->shared->page_dirty[slotno]);
774 
775  LWLockRelease(CLogControlLock);
776  }
777  else if (info == CLOG_TRUNCATE)
778  {
779  xl_clog_truncate xlrec;
780 
781  memcpy(&xlrec, XLogRecGetData(record), sizeof(xl_clog_truncate));
782 
783  /*
784  * During XLOG replay, latest_page_number isn't set up yet; insert a
785  * suitable value to bypass the sanity test in SimpleLruTruncate.
786  */
787  ClogCtl->shared->latest_page_number = xlrec.pageno;
788 
790 
792  }
793  else
794  elog(PANIC, "clog_redo: unknown op code %u", info);
795 }
void SimpleLruTruncate(SlruCtl ctl, int cutoffPage)
Definition: slru.c:1169
unsigned char uint8
Definition: c.h:266
#define PANIC
Definition: elog.h:53
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
#define ClogCtl
Definition: clog.c:80
#define CLOG_ZEROPAGE
Definition: clog.h:54
void AdvanceOldestClogXid(TransactionId oldest_datfrozenxid)
Definition: varsup.c:271
#define XLogRecGetData(decoder)
Definition: xlogreader.h:220
void SimpleLruWritePage(SlruCtl ctl, int slotno)
Definition: slru.c:578
int pageno
Definition: clog.h:33
#define CLOG_TRUNCATE
Definition: clog.h:55
#define XLogRecGetInfo(decoder)
Definition: xlogreader.h:216
TransactionId oldestXact
Definition: clog.h:34
#define Assert(condition)
Definition: c.h:676
#define XLR_INFO_MASK
Definition: xlogrecord.h:62
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1111
static int ZeroCLOGPage(int pageno, bool writeXlog)
Definition: clog.c:490
#define XLogRecHasAnyBlockRefs(decoder)
Definition: xlogreader.h:222
#define elog
Definition: elog.h:219
Size CLOGShmemBuffers ( void  )

Definition at line 435 of file clog.c.

References Max, Min, and NBuffers.

Referenced by CLOGShmemInit(), and CLOGShmemSize().

436 {
437  return Min(128, Max(4, NBuffers / 512));
438 }
#define Min(x, y)
Definition: c.h:807
#define Max(x, y)
Definition: c.h:801
int NBuffers
Definition: globals.c:123
void CLOGShmemInit ( void  )

Definition at line 450 of file clog.c.

References CLOG_LSNS_PER_PAGE, ClogCtl, CLOGPagePrecedes(), CLOGShmemBuffers(), LWTRANCHE_CLOG_BUFFERS, and SimpleLruInit().

Referenced by CreateSharedMemoryAndSemaphores().

451 {
452  ClogCtl->PagePrecedes = CLOGPagePrecedes;
454  CLogControlLock, "pg_xact", LWTRANCHE_CLOG_BUFFERS);
455 }
#define ClogCtl
Definition: clog.c:80
#define CLOG_LSNS_PER_PAGE
Definition: clog.c:69
static bool CLOGPagePrecedes(int page1, int page2)
Definition: clog.c:704
Size CLOGShmemBuffers(void)
Definition: clog.c:435
void SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns, LWLock *ctllock, const char *subdir, int tranche_id)
Definition: slru.c:165
Size CLOGShmemSize ( void  )

Definition at line 444 of file clog.c.

References CLOG_LSNS_PER_PAGE, CLOGShmemBuffers(), and SimpleLruShmemSize().

Referenced by CreateSharedMemoryAndSemaphores().

445 {
447 }
Size SimpleLruShmemSize(int nslots, int nlsns)
Definition: slru.c:145
#define CLOG_LSNS_PER_PAGE
Definition: clog.c:69
Size CLOGShmemBuffers(void)
Definition: clog.c:435
void ExtendCLOG ( TransactionId  newestXact)

Definition at line 619 of file clog.c.

References FirstNormalTransactionId, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), TransactionIdEquals, TransactionIdToPage, TransactionIdToPgIndex, and ZeroCLOGPage().

Referenced by GetNewTransactionId().

620 {
621  int pageno;
622 
623  /*
624  * No work except at first XID of a page. But beware: just after
625  * wraparound, the first XID of page zero is FirstNormalTransactionId.
626  */
627  if (TransactionIdToPgIndex(newestXact) != 0 &&
629  return;
630 
631  pageno = TransactionIdToPage(newestXact);
632 
633  LWLockAcquire(CLogControlLock, LW_EXCLUSIVE);
634 
635  /* Zero the page and make an XLOG entry about it */
636  ZeroCLOGPage(pageno, true);
637 
638  LWLockRelease(CLogControlLock);
639 }
#define TransactionIdToPage(xid)
Definition: clog.c:62
#define TransactionIdEquals(id1, id2)
Definition: transam.h:43
#define TransactionIdToPgIndex(xid)
Definition: clog.c:63
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
#define FirstNormalTransactionId
Definition: transam.h:34
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1111
static int ZeroCLOGPage(int pageno, bool writeXlog)
Definition: clog.c:490
void ShutdownCLOG ( void  )

Definition at line 575 of file clog.c.

References ClogCtl, fsync_fname(), and SimpleLruFlush().

Referenced by ShutdownXLOG().

576 {
577  /* Flush dirty CLOG pages to disk */
578  TRACE_POSTGRESQL_CLOG_CHECKPOINT_START(false);
579  SimpleLruFlush(ClogCtl, false);
580 
581  /*
582  * fsync pg_xact to ensure that any files flushed previously are durably
583  * on disk.
584  */
585  fsync_fname("pg_xact", true);
586 
587  TRACE_POSTGRESQL_CLOG_CHECKPOINT_DONE(false);
588 }
void fsync_fname(const char *fname, bool isdir)
Definition: fd.c:567
void SimpleLruFlush(SlruCtl ctl, bool allow_redirtied)
Definition: slru.c:1104
#define ClogCtl
Definition: clog.c:80
void StartupCLOG ( void  )

Definition at line 507 of file clog.c.

References ClogCtl, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), VariableCacheData::nextXid, ShmemVariableCache, and TransactionIdToPage.

Referenced by StartupXLOG().

508 {
510  int pageno = TransactionIdToPage(xid);
511 
512  LWLockAcquire(CLogControlLock, LW_EXCLUSIVE);
513 
514  /*
515  * Initialize our idea of the latest page number.
516  */
517  ClogCtl->shared->latest_page_number = pageno;
518 
519  LWLockRelease(CLogControlLock);
520 }
#define TransactionIdToPage(xid)
Definition: clog.c:62
uint32 TransactionId
Definition: c.h:397
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
#define ClogCtl
Definition: clog.c:80
TransactionId nextXid
Definition: transam.h:117
VariableCache ShmemVariableCache
Definition: varsup.c:34
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1111
XidStatus TransactionIdGetStatus ( TransactionId  xid,
XLogRecPtr lsn 
)

Definition at line 393 of file clog.c.

References CLOG_BITS_PER_XACT, CLOG_XACT_BITMASK, ClogCtl, GetLSNIndex, LWLockRelease(), SimpleLruReadPage_ReadOnly(), status(), TransactionIdToBIndex, TransactionIdToByte, and TransactionIdToPage.

Referenced by TransactionIdGetCommitLSN(), and TransactionLogFetch().

394 {
395  int pageno = TransactionIdToPage(xid);
396  int byteno = TransactionIdToByte(xid);
397  int bshift = TransactionIdToBIndex(xid) * CLOG_BITS_PER_XACT;
398  int slotno;
399  int lsnindex;
400  char *byteptr;
402 
403  /* lock is acquired by SimpleLruReadPage_ReadOnly */
404 
405  slotno = SimpleLruReadPage_ReadOnly(ClogCtl, pageno, xid);
406  byteptr = ClogCtl->shared->page_buffer[slotno] + byteno;
407 
408  status = (*byteptr >> bshift) & CLOG_XACT_BITMASK;
409 
410  lsnindex = GetLSNIndex(slotno, xid);
411  *lsn = ClogCtl->shared->group_lsn[lsnindex];
412 
413  LWLockRelease(CLogControlLock);
414 
415  return status;
416 }
#define TransactionIdToBIndex(xid)
Definition: clog.c:65
#define CLOG_XACT_BITMASK
Definition: clog.c:60
#define TransactionIdToPage(xid)
Definition: clog.c:62
#define GetLSNIndex(slotno, xid)
Definition: clog.c:71
int XidStatus
Definition: clog.h:24
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
#define ClogCtl
Definition: clog.c:80
#define CLOG_BITS_PER_XACT
Definition: clog.c:57
int SimpleLruReadPage_ReadOnly(SlruCtl ctl, int pageno, TransactionId xid)
Definition: slru.c:467
#define TransactionIdToByte(xid)
Definition: clog.c:64
static void static void status(const char *fmt,...) pg_attribute_printf(1
Definition: pg_regress.c:224
void TransactionIdSetTreeStatus ( TransactionId  xid,
int  nsubxids,
TransactionId subxids,
XidStatus  status,
XLogRecPtr  lsn 
)

Definition at line 149 of file clog.c.

References Assert, i, set_status_by_pages(), TRANSACTION_STATUS_ABORTED, TRANSACTION_STATUS_COMMITTED, TRANSACTION_STATUS_SUB_COMMITTED, TransactionIdSetPageStatus(), and TransactionIdToPage.

Referenced by TransactionIdAbortTree(), TransactionIdAsyncCommitTree(), and TransactionIdCommitTree().

151 {
152  int pageno = TransactionIdToPage(xid); /* get page of parent */
153  int i;
154 
157 
158  /*
159  * See how many subxids, if any, are on the same page as the parent, if
160  * any.
161  */
162  for (i = 0; i < nsubxids; i++)
163  {
164  if (TransactionIdToPage(subxids[i]) != pageno)
165  break;
166  }
167 
168  /*
169  * Do all items fit on a single page?
170  */
171  if (i == nsubxids)
172  {
173  /*
174  * Set the parent and all subtransactions in a single call
175  */
176  TransactionIdSetPageStatus(xid, nsubxids, subxids, status, lsn,
177  pageno);
178  }
179  else
180  {
181  int nsubxids_on_first_page = i;
182 
183  /*
184  * If this is a commit then we care about doing this correctly (i.e.
185  * using the subcommitted intermediate status). By here, we know
186  * we're updating more than one page of clog, so we must mark entries
187  * that are *not* on the first page so that they show as subcommitted
188  * before we then return to update the status to fully committed.
189  *
190  * To avoid touching the first page twice, skip marking subcommitted
191  * for the subxids on that first page.
192  */
194  set_status_by_pages(nsubxids - nsubxids_on_first_page,
195  subxids + nsubxids_on_first_page,
197 
198  /*
199  * Now set the parent and subtransactions on same page as the parent,
200  * if any
201  */
202  pageno = TransactionIdToPage(xid);
203  TransactionIdSetPageStatus(xid, nsubxids_on_first_page, subxids, status,
204  lsn, pageno);
205 
206  /*
207  * Now work through the rest of the subxids one clog page at a time,
208  * starting from the second page onwards, like we did above.
209  */
210  set_status_by_pages(nsubxids - nsubxids_on_first_page,
211  subxids + nsubxids_on_first_page,
212  status, lsn);
213  }
214 }
#define TransactionIdToPage(xid)
Definition: clog.c:62
#define TRANSACTION_STATUS_COMMITTED
Definition: clog.h:27
#define TRANSACTION_STATUS_ABORTED
Definition: clog.h:28
#define TRANSACTION_STATUS_SUB_COMMITTED
Definition: clog.h:29
static void set_status_by_pages(int nsubxids, TransactionId *subxids, XidStatus status, XLogRecPtr lsn)
Definition: clog.c:223
#define Assert(condition)
Definition: c.h:676
int i
static void static void status(const char *fmt,...) pg_attribute_printf(1
Definition: pg_regress.c:224
static void TransactionIdSetPageStatus(TransactionId xid, int nsubxids, TransactionId *subxids, XidStatus status, XLogRecPtr lsn, int pageno)
Definition: clog.c:255
void TrimCLOG ( void  )

Definition at line 526 of file clog.c.

References CLOG_BITS_PER_XACT, ClogCtl, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MemSet, VariableCacheData::nextXid, ShmemVariableCache, SimpleLruReadPage(), TransactionIdToBIndex, TransactionIdToByte, TransactionIdToPage, and TransactionIdToPgIndex.

Referenced by StartupXLOG().

527 {
529  int pageno = TransactionIdToPage(xid);
530 
531  LWLockAcquire(CLogControlLock, LW_EXCLUSIVE);
532 
533  /*
534  * Re-Initialize our idea of the latest page number.
535  */
536  ClogCtl->shared->latest_page_number = pageno;
537 
538  /*
539  * Zero out the remainder of the current clog page. Under normal
540  * circumstances it should be zeroes already, but it seems at least
541  * theoretically possible that XLOG replay will have settled on a nextXID
542  * value that is less than the last XID actually used and marked by the
543  * previous database lifecycle (since subtransaction commit writes clog
544  * but makes no WAL entry). Let's just be safe. (We need not worry about
545  * pages beyond the current one, since those will be zeroed when first
546  * used. For the same reason, there is no need to do anything when
547  * nextXid is exactly at a page boundary; and it's likely that the
548  * "current" page doesn't exist yet in that case.)
549  */
550  if (TransactionIdToPgIndex(xid) != 0)
551  {
552  int byteno = TransactionIdToByte(xid);
553  int bshift = TransactionIdToBIndex(xid) * CLOG_BITS_PER_XACT;
554  int slotno;
555  char *byteptr;
556 
557  slotno = SimpleLruReadPage(ClogCtl, pageno, false, xid);
558  byteptr = ClogCtl->shared->page_buffer[slotno] + byteno;
559 
560  /* Zero so-far-unused positions in the current byte */
561  *byteptr &= (1 << bshift) - 1;
562  /* Zero the rest of the page */
563  MemSet(byteptr + 1, 0, BLCKSZ - byteno - 1);
564 
565  ClogCtl->shared->page_dirty[slotno] = true;
566  }
567 
568  LWLockRelease(CLogControlLock);
569 }
#define TransactionIdToBIndex(xid)
Definition: clog.c:65
#define TransactionIdToPage(xid)
Definition: clog.c:62
uint32 TransactionId
Definition: c.h:397
#define TransactionIdToPgIndex(xid)
Definition: clog.c:63
#define MemSet(start, val, len)
Definition: c.h:858
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
#define ClogCtl
Definition: clog.c:80
TransactionId nextXid
Definition: transam.h:117
int SimpleLruReadPage(SlruCtl ctl, int pageno, bool write_ok, TransactionId xid)
Definition: slru.c:375
VariableCache ShmemVariableCache
Definition: varsup.c:34
#define CLOG_BITS_PER_XACT
Definition: clog.c:57
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1111
#define TransactionIdToByte(xid)
Definition: clog.c:64
void TruncateCLOG ( TransactionId  oldestXact,
Oid  oldestxid_datoid 
)

Definition at line 658 of file clog.c.

References AdvanceOldestClogXid(), ClogCtl, SimpleLruTruncate(), SlruScanDirCbReportPresence(), SlruScanDirectory(), TransactionIdToPage, and WriteTruncateXlogRec().

Referenced by vac_truncate_clog().

659 {
660  int cutoffPage;
661 
662  /*
663  * The cutoff point is the start of the segment containing oldestXact. We
664  * pass the *page* containing oldestXact to SimpleLruTruncate.
665  */
666  cutoffPage = TransactionIdToPage(oldestXact);
667 
668  /* Check to see if there's any files that could be removed */
670  return; /* nothing to remove */
671 
672  /*
673  * Advance oldestClogXid before truncating clog, so concurrent xact status
674  * lookups can ensure they don't attempt to access truncated-away clog.
675  *
676  * It's only necessary to do this if we will actually truncate away clog
677  * pages.
678  */
679  AdvanceOldestClogXid(oldestXact);
680 
681  /*
682  * Write XLOG record and flush XLOG to disk. We record the oldest xid
683  * we're keeping information about here so we can ensure that it's always
684  * ahead of clog truncation in case we crash, and so a standby finds out
685  * the new valid xid before the next checkpoint.
686  */
687  WriteTruncateXlogRec(cutoffPage, oldestXact, oldestxid_datoid);
688 
689  /* Now we can remove the old CLOG segment(s) */
690  SimpleLruTruncate(ClogCtl, cutoffPage);
691 }
#define TransactionIdToPage(xid)
Definition: clog.c:62
void SimpleLruTruncate(SlruCtl ctl, int cutoffPage)
Definition: slru.c:1169
#define ClogCtl
Definition: clog.c:80
void AdvanceOldestClogXid(TransactionId oldest_datfrozenxid)
Definition: varsup.c:271
bool SlruScanDirCbReportPresence(SlruCtl ctl, char *filename, int segpage, void *data)
Definition: slru.c:1322
bool SlruScanDirectory(SlruCtl ctl, SlruScanCallback callback, void *data)
Definition: slru.c:1377
static void WriteTruncateXlogRec(int pageno, TransactionId oldestXact, Oid oldestXidDb)
Definition: clog.c:736