/*------------------------------------------------------------------------- * * heapam.c * heap access method code * * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.239 2007/09/07 20:59:26 tgl Exp $ * * * INTERFACE ROUTINES * relation_open - open any relation by relation OID * relation_openrv - open any relation specified by a RangeVar * relation_close - close any relation * heap_open - open a heap relation by relation OID * heap_openrv - open a heap relation specified by a RangeVar * heap_close - (now just a macro for relation_close) * heap_beginscan - begin relation scan * heap_rescan - restart a relation scan * heap_endscan - end relation scan * heap_getnext - retrieve next tuple in scan * heap_fetch - retrieve tuple with given tid * heap_insert - insert tuple into a relation * heap_delete - delete a tuple from a relation * heap_update - replace a tuple in a relation with another tuple * heap_markpos - mark scan position * heap_restrpos - restore position to marked location * heap_sync - sync heap, for when no WAL has been written * * NOTES * This file contains the heap_ routines which implement * the POSTGRES heap access method used for all POSTGRES * relations. * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/heapam.h" #include "access/hio.h" #include "access/multixact.h" #include "access/transam.h" #include "access/tuptoaster.h" #include "access/valid.h" #include "access/xact.h" #include "catalog/catalog.h" #include "catalog/namespace.h" #include "miscadmin.h" #include "pgstat.h" #include "storage/procarray.h" #include "storage/smgr.h" #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/relcache.h" #include "utils/syscache.h" static HeapScanDesc heap_beginscan_internal(Relation relation, Snapshot snapshot, int nkeys, ScanKey key, bool is_bitmapscan); static XLogRecPtr log_heap_update(Relation reln, Buffer oldbuf, ItemPointerData from, Buffer newbuf, HeapTuple newtup, bool move); /* ---------------------------------------------------------------- * heap support routines * ---------------------------------------------------------------- */ /* ---------------- * initscan - scan code common to heap_beginscan and heap_rescan * ---------------- */ static void initscan(HeapScanDesc scan, ScanKey key) { /* * Determine the number of blocks we have to scan. * * It is sufficient to do this once at scan start, since any tuples added * while the scan is in progress will be invisible to my snapshot * anyway. (That is not true when using a non-MVCC snapshot. However, * we couldn't guarantee to return tuples added after scan start anyway, * since they might go into pages we already scanned. To guarantee * consistent results for a non-MVCC snapshot, the caller must hold some * higher-level lock that ensures the interesting tuple(s) won't change.) */ scan->rs_nblocks = RelationGetNumberOfBlocks(scan->rs_rd); /* * If the table is large relative to NBuffers, use a bulk-read access * strategy and enable synchronized scanning (see syncscan.c). Although * the thresholds for these features could be different, we make them the * same so that there are only two behaviors to tune rather than four. * * During a rescan, don't make a new strategy object if we don't have to. */ if (!scan->rs_bitmapscan && !scan->rs_rd->rd_istemp && scan->rs_nblocks > NBuffers / 4) { if (scan->rs_strategy == NULL) scan->rs_strategy = GetAccessStrategy(BAS_BULKREAD); scan->rs_syncscan = true; scan->rs_startblock = ss_get_location(scan->rs_rd, scan->rs_nblocks); } else { if (scan->rs_strategy != NULL) FreeAccessStrategy(scan->rs_strategy); scan->rs_strategy = NULL; scan->rs_syncscan = false; scan->rs_startblock = 0; } scan->rs_inited = false; scan->rs_ctup.t_data = NULL; ItemPointerSetInvalid(&scan->rs_ctup.t_self); scan->rs_cbuf = InvalidBuffer; scan->rs_cblock = InvalidBlockNumber; /* we don't have a marked position... */ ItemPointerSetInvalid(&(scan->rs_mctid)); /* page-at-a-time fields are always invalid when not rs_inited */ /* * copy the scan key, if appropriate */ if (key != NULL) memcpy(scan->rs_key, key, scan->rs_nkeys * sizeof(ScanKeyData)); /* * Currently, we don't have a stats counter for bitmap heap scans * (but the underlying bitmap index scans will be counted). */ if (!scan->rs_bitmapscan) pgstat_count_heap_scan(scan->rs_rd); } /* * heapgetpage - subroutine for heapgettup() * * This routine reads and pins the specified page of the relation. * In page-at-a-time mode it performs additional work, namely determining * which tuples on the page are visible. */ static void heapgetpage(HeapScanDesc scan, BlockNumber page) { Buffer buffer; Snapshot snapshot; Page dp; int lines; int ntup; OffsetNumber lineoff; ItemId lpp; Assert(page < scan->rs_nblocks); /* release previous scan buffer, if any */ if (BufferIsValid(scan->rs_cbuf)) { ReleaseBuffer(scan->rs_cbuf); scan->rs_cbuf = InvalidBuffer; } /* read page using selected strategy */ scan->rs_cbuf = ReadBufferWithStrategy(scan->rs_rd, page, scan->rs_strategy); scan->rs_cblock = page; if (!scan->rs_pageatatime) return; buffer = scan->rs_cbuf; snapshot = scan->rs_snapshot; /* * We must hold share lock on the buffer content while examining tuple * visibility. Afterwards, however, the tuples we have found to be * visible are guaranteed good as long as we hold the buffer pin. */ LockBuffer(buffer, BUFFER_LOCK_SHARE); dp = (Page) BufferGetPage(buffer); lines = PageGetMaxOffsetNumber(dp); ntup = 0; for (lineoff = FirstOffsetNumber, lpp = PageGetItemId(dp, lineoff); lineoff <= lines; lineoff++, lpp++) { if (ItemIdIsUsed(lpp)) { HeapTupleData loctup; bool valid; loctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp); loctup.t_len = ItemIdGetLength(lpp); ItemPointerSet(&(loctup.t_self), page, lineoff); valid = HeapTupleSatisfiesVisibility(&loctup, snapshot, buffer); if (valid) scan->rs_vistuples[ntup++] = lineoff; } } LockBuffer(buffer, BUFFER_LOCK_UNLOCK); Assert(ntup <= MaxHeapTuplesPerPage); scan->rs_ntuples = ntup; } /* ---------------- * heapgettup - fetch next heap tuple * * Initialize the scan if not already done; then advance to the next * tuple as indicated by "dir"; return the next tuple in scan->rs_ctup, * or set scan->rs_ctup.t_data = NULL if no more tuples. * * dir == NoMovementScanDirection means "re-fetch the tuple indicated * by scan->rs_ctup". * * Note: the reason nkeys/key are passed separately, even though they are * kept in the scan descriptor, is that the caller may not want us to check * the scankeys. * * Note: when we fall off the end of the scan in either direction, we * reset rs_inited. This means that a further request with the same * scan direction will restart the scan, which is a bit odd, but a * request with the opposite scan direction will start a fresh scan * in the proper direction. The latter is required behavior for cursors, * while the former case is generally undefined behavior in Postgres * so we don't care too much. * ---------------- */ static void heapgettup(HeapScanDesc scan, ScanDirection dir, int nkeys, ScanKey key) { HeapTuple tuple = &(scan->rs_ctup); Snapshot snapshot = scan->rs_snapshot; bool backward = ScanDirectionIsBackward(dir); BlockNumber page; bool finished; Page dp; int lines; OffsetNumber lineoff; int linesleft; ItemId lpp; /* * calculate next starting lineoff, given scan direction */ if (ScanDirectionIsForward(dir)) { if (!scan->rs_inited) { /* * return null immediately if relation is empty */ if (scan->rs_nblocks == 0) { Assert(!BufferIsValid(scan->rs_cbuf)); tuple->t_data = NULL; return; } page = scan->rs_startblock; /* first page */ heapgetpage(scan, page); lineoff = FirstOffsetNumber; /* first offnum */ scan->rs_inited = true; } else { /* continue from previously returned page/tuple */ page = scan->rs_cblock; /* current page */ lineoff = /* next offnum */ OffsetNumberNext(ItemPointerGetOffsetNumber(&(tuple->t_self))); } LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE); dp = (Page) BufferGetPage(scan->rs_cbuf); lines = PageGetMaxOffsetNumber(dp); /* page and lineoff now reference the physically next tid */ linesleft = lines - lineoff + 1; } else if (backward) { if (!scan->rs_inited) { /* * return null immediately if relation is empty */ if (scan->rs_nblocks == 0) { Assert(!BufferIsValid(scan->rs_cbuf)); tuple->t_data = NULL; return; } /* * Disable reporting to syncscan logic in a backwards scan; it's * not very likely anyone else is doing the same thing at the same * time, and much more likely that we'll just bollix things for * forward scanners. */ scan->rs_syncscan = false; /* start from last page of the scan */ if (scan->rs_startblock > 0) page = scan->rs_startblock - 1; else page = scan->rs_nblocks - 1; heapgetpage(scan, page); } else { /* continue from previously returned page/tuple */ page = scan->rs_cblock; /* current page */ } LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE); dp = (Page) BufferGetPage(scan->rs_cbuf); lines = PageGetMaxOffsetNumber(dp); if (!scan->rs_inited) { lineoff = lines; /* final offnum */ scan->rs_inited = true; } else { lineoff = /* previous offnum */ OffsetNumberPrev(ItemPointerGetOffsetNumber(&(tuple->t_self))); } /* page and lineoff now reference the physically previous tid */ linesleft = lineoff; } else { /* * ``no movement'' scan direction: refetch prior tuple */ if (!scan->rs_inited) { Assert(!BufferIsValid(scan->rs_cbuf)); tuple->t_data = NULL; return; } page = ItemPointerGetBlockNumber(&(tuple->t_self)); if (page != scan->rs_cblock) heapgetpage(scan, page); /* Since the tuple was previously fetched, needn't lock page here */ dp = (Page) BufferGetPage(scan->rs_cbuf); lineoff = ItemPointerGetOffsetNumber(&(tuple->t_self)); lpp = PageGetItemId(dp, lineoff); tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp); tuple->t_len = ItemIdGetLength(lpp); return; } /* * advance the scan until we find a qualifying tuple or run out of stuff * to scan */ lpp = PageGetItemId(dp, lineoff); for (;;) { while (linesleft > 0) { if (ItemIdIsUsed(lpp)) { bool valid; tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp); tuple->t_len = ItemIdGetLength(lpp); ItemPointerSet(&(tuple->t_self), page, lineoff); /* * if current tuple qualifies, return it. */ valid = HeapTupleSatisfiesVisibility(tuple, snapshot, scan->rs_cbuf); if (valid && key != NULL) HeapKeyTest(tuple, RelationGetDescr(scan->rs_rd), nkeys, key, valid); if (valid) { LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK); return; } } /* * otherwise move to the next item on the page */ --linesleft; if (backward) { --lpp; /* move back in this page's ItemId array */ --lineoff; } else { ++lpp; /* move forward in this page's ItemId array */ ++lineoff; } } /* * if we get here, it means we've exhausted the items on this page and * it's time to move to the next. */ LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK); /* * advance to next/prior page and detect end of scan */ if (backward) { finished = (page == scan->rs_startblock); if (page == 0) page = scan->rs_nblocks; page--; } else { page++; if (page >= scan->rs_nblocks) page = 0; finished = (page == scan->rs_startblock); /* * Report our new scan position for synchronization purposes. * We don't do that when moving backwards, however. That would * just mess up any other forward-moving scanners. * * Note: we do this before checking for end of scan so that the * final state of the position hint is back at the start of the * rel. That's not strictly necessary, but otherwise when you run * the same query multiple times the starting position would shift * a little bit backwards on every invocation, which is confusing. * We don't guarantee any specific ordering in general, though. */ if (scan->rs_syncscan) ss_report_location(scan->rs_rd, page); } /* * return NULL if we've exhausted all the pages */ if (finished) { if (BufferIsValid(scan->rs_cbuf)) ReleaseBuffer(scan->rs_cbuf); scan->rs_cbuf = InvalidBuffer; scan->rs_cblock = InvalidBlockNumber; tuple->t_data = NULL; scan->rs_inited = false; return; } heapgetpage(scan, page); LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE); dp = (Page) BufferGetPage(scan->rs_cbuf); lines = PageGetMaxOffsetNumber((Page) dp); linesleft = lines; if (backward) { lineoff = lines; lpp = PageGetItemId(dp, lines); } else { lineoff = FirstOffsetNumber; lpp = PageGetItemId(dp, FirstOffsetNumber); } } } /* ---------------- * heapgettup_pagemode - fetch next heap tuple in page-at-a-time mode * * Same API as heapgettup, but used in page-at-a-time mode * * The internal logic is much the same as heapgettup's too, but there are some * differences: we do not take the buffer content lock (that only needs to * happen inside heapgetpage), and we iterate through just the tuples listed * in rs_vistuples[] rather than all tuples on the page. Notice that * lineindex is 0-based, where the corresponding loop variable lineoff in * heapgettup is 1-based. * ---------------- */ static void heapgettup_pagemode(HeapScanDesc scan, ScanDirection dir, int nkeys, ScanKey key) { HeapTuple tuple = &(scan->rs_ctup); bool backward = ScanDirectionIsBackward(dir); BlockNumber page; bool finished; Page dp; int lines; int lineindex; OffsetNumber lineoff; int linesleft; ItemId lpp; /* * calculate next starting lineindex, given scan direction */ if (ScanDirectionIsForward(dir)) { if (!scan->rs_inited) { /* * return null immediately if relation is empty */ if (scan->rs_nblocks == 0) { Assert(!BufferIsValid(scan->rs_cbuf)); tuple->t_data = NULL; return; } page = scan->rs_startblock; /* first page */ heapgetpage(scan, page); lineindex = 0; scan->rs_inited = true; } else { /* continue from previously returned page/tuple */ page = scan->rs_cblock; /* current page */ lineindex = scan->rs_cindex + 1; } dp = (Page) BufferGetPage(scan->rs_cbuf); lines = scan->rs_ntuples; /* page and lineindex now reference the next visible tid */ linesleft = lines - lineindex; } else if (backward) { if (!scan->rs_inited) { /* * return null immediately if relation is empty */ if (scan->rs_nblocks == 0) { Assert(!BufferIsValid(scan->rs_cbuf)); tuple->t_data = NULL; return; } /* * Disable reporting to syncscan logic in a backwards scan; it's * not very likely anyone else is doing the same thing at the same * time, and much more likely that we'll just bollix things for * forward scanners. */ scan->rs_syncscan = false; /* start from last page of the scan */ if (scan->rs_startblock > 0) page = scan->rs_startblock - 1; else page = scan->rs_nblocks - 1; heapgetpage(scan, page); } else { /* continue from previously returned page/tuple */ page = scan->rs_cblock; /* current page */ } dp = (Page) BufferGetPage(scan->rs_cbuf); lines = scan->rs_ntuples; if (!scan->rs_inited) { lineindex = lines - 1; scan->rs_inited = true; } else { lineindex = scan->rs_cindex - 1; } /* page and lineindex now reference the previous visible tid */ linesleft = lineindex + 1; } else { /* * ``no movement'' scan direction: refetch prior tuple */ if (!scan->rs_inited) { Assert(!BufferIsValid(scan->rs_cbuf)); tuple->t_data = NULL; return; } page = ItemPointerGetBlockNumber(&(tuple->t_self)); if (page != scan->rs_cblock) heapgetpage(scan, page); /* Since the tuple was previously fetched, needn't lock page here */ dp = (Page) BufferGetPage(scan->rs_cbuf); lineoff = ItemPointerGetOffsetNumber(&(tuple->t_self)); lpp = PageGetItemId(dp, lineoff); tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp); tuple->t_len = ItemIdGetLength(lpp); /* check that rs_cindex is in sync */ Assert(scan->rs_cindex < scan->rs_ntuples); Assert(lineoff == scan->rs_vistuples[scan->rs_cindex]); return; } /* * advance the scan until we find a qualifying tuple or run out of stuff * to scan */ for (;;) { while (linesleft > 0) { lineoff = scan->rs_vistuples[lineindex]; lpp = PageGetItemId(dp, lineoff); Assert(ItemIdIsUsed(lpp)); tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp); tuple->t_len = ItemIdGetLength(lpp); ItemPointerSet(&(tuple->t_self), page, lineoff); /* * if current tuple qualifies, return it. */ if (key != NULL) { bool valid; HeapKeyTest(tuple, RelationGetDescr(scan->rs_rd), nkeys, key, valid); if (valid) { scan->rs_cindex = lineindex; return; } } else { scan->rs_cindex = lineindex; return; } /* * otherwise move to the next item on the page */ --linesleft; if (backward) --lineindex; else ++lineindex; } /* * if we get here, it means we've exhausted the items on this page and * it's time to move to the next. */ if (backward) { finished = (page == scan->rs_startblock); if (page == 0) page = scan->rs_nblocks; page--; } else { page++; if (page >= scan->rs_nblocks) page = 0; finished = (page == scan->rs_startblock); /* * Report our new scan position for synchronization purposes. * We don't do that when moving backwards, however. That would * just mess up any other forward-moving scanners. * * Note: we do this before checking for end of scan so that the * final state of the position hint is back at the start of the * rel. That's not strictly necessary, but otherwise when you run * the same query multiple times the starting position would shift * a little bit backwards on every invocation, which is confusing. * We don't guarantee any specific ordering in general, though. */ if (scan->rs_syncscan) ss_report_location(scan->rs_rd, page); } /* * return NULL if we've exhausted all the pages */ if (finished) { if (BufferIsValid(scan->rs_cbuf)) ReleaseBuffer(scan->rs_cbuf); scan->rs_cbuf = InvalidBuffer; scan->rs_cblock = InvalidBlockNumber; tuple->t_data = NULL; scan->rs_inited = false; return; } heapgetpage(scan, page); dp = (Page) BufferGetPage(scan->rs_cbuf); lines = scan->rs_ntuples; linesleft = lines; if (backward) lineindex = lines - 1; else lineindex = 0; } } #if defined(DISABLE_COMPLEX_MACRO) /* * This is formatted so oddly so that the correspondence to the macro * definition in access/heapam.h is maintained. */ Datum fastgetattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull) { return ( (attnum) > 0 ? ( ((isnull) ? (*(isnull) = false) : (dummyret) NULL), HeapTupleNoNulls(tup) ? ( (tupleDesc)->attrs[(attnum) - 1]->attcacheoff >= 0 ? ( fetchatt((tupleDesc)->attrs[(attnum) - 1], (char *) (tup)->t_data + (tup)->t_data->t_hoff + (tupleDesc)->attrs[(attnum) - 1]->attcacheoff) ) : nocachegetattr((tup), (attnum), (tupleDesc), (isnull)) ) : ( att_isnull((attnum) - 1, (tup)->t_data->t_bits) ? ( ((isnull) ? (*(isnull) = true) : (dummyret) NULL), (Datum) NULL ) : ( nocachegetattr((tup), (attnum), (tupleDesc), (isnull)) ) ) ) : ( (Datum) NULL ) ); } #endif /* defined(DISABLE_COMPLEX_MACRO) */ /* ---------------------------------------------------------------- * heap access method interface * ---------------------------------------------------------------- */ /* ---------------- * relation_open - open any relation by relation OID * * If lockmode is not "NoLock", the specified kind of lock is * obtained on the relation. (Generally, NoLock should only be * used if the caller knows it has some appropriate lock on the * relation already.) * * An error is raised if the relation does not exist. * * NB: a "relation" is anything with a pg_class entry. The caller is * expected to check whether the relkind is something it can handle. * ---------------- */ Relation relation_open(Oid relationId, LOCKMODE lockmode) { Relation r; Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES); /* Get the lock before trying to open the relcache entry */ if (lockmode != NoLock) LockRelationOid(relationId, lockmode); /* The relcache does all the real work... */ r = RelationIdGetRelation(relationId); if (!RelationIsValid(r)) elog(ERROR, "could not open relation with OID %u", relationId); pgstat_initstats(r); return r; } /* ---------------- * try_relation_open - open any relation by relation OID * * Same as relation_open, except return NULL instead of failing * if the relation does not exist. * ---------------- */ Relation try_relation_open(Oid relationId, LOCKMODE lockmode) { Relation r; Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES); /* Get the lock first */ if (lockmode != NoLock) LockRelationOid(relationId, lockmode); /* * Now that we have the lock, probe to see if the relation really exists * or not. */ if (!SearchSysCacheExists(RELOID, ObjectIdGetDatum(relationId), 0, 0, 0)) { /* Release useless lock */ if (lockmode != NoLock) UnlockRelationOid(relationId, lockmode); return NULL; } /* Should be safe to do a relcache load */ r = RelationIdGetRelation(relationId); if (!RelationIsValid(r)) elog(ERROR, "could not open relation with OID %u", relationId); pgstat_initstats(r); return r; } /* ---------------- * relation_open_nowait - open but don't wait for lock * * Same as relation_open, except throw an error instead of waiting * when the requested lock is not immediately obtainable. * ---------------- */ Relation relation_open_nowait(Oid relationId, LOCKMODE lockmode) { Relation r; Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES); /* Get the lock before trying to open the relcache entry */ if (lockmode != NoLock) { if (!ConditionalLockRelationOid(relationId, lockmode)) { /* try to throw error by name; relation could be deleted... */ char *relname = get_rel_name(relationId); if (relname) ereport(ERROR, (errcode(ERRCODE_LOCK_NOT_AVAILABLE), errmsg("could not obtain lock on relation \"%s\"", relname))); else ereport(ERROR, (errcode(ERRCODE_LOCK_NOT_AVAILABLE), errmsg("could not obtain lock on relation with OID %u", relationId))); } } /* The relcache does all the real work... */ r = RelationIdGetRelation(relationId); if (!RelationIsValid(r)) elog(ERROR, "could not open relation with OID %u", relationId); pgstat_initstats(r); return r; } /* ---------------- * relation_openrv - open any relation specified by a RangeVar * * Same as relation_open, but the relation is specified by a RangeVar. * ---------------- */ Relation relation_openrv(const RangeVar *relation, LOCKMODE lockmode) { Oid relOid; /* * Check for shared-cache-inval messages before trying to open the * relation. This is needed to cover the case where the name identifies a * rel that has been dropped and recreated since the start of our * transaction: if we don't flush the old syscache entry then we'll latch * onto that entry and suffer an error when we do RelationIdGetRelation. * Note that relation_open does not need to do this, since a relation's * OID never changes. * * We skip this if asked for NoLock, on the assumption that the caller has * already ensured some appropriate lock is held. */ if (lockmode != NoLock) AcceptInvalidationMessages(); /* Look up the appropriate relation using namespace search */ relOid = RangeVarGetRelid(relation, false); /* Let relation_open do the rest */ return relation_open(relOid, lockmode); } /* ---------------- * relation_close - close any relation * * If lockmode is not "NoLock", we then release the specified lock. * * Note that it is often sensible to hold a lock beyond relation_close; * in that case, the lock is released automatically at xact end. * ---------------- */ void relation_close(Relation relation, LOCKMODE lockmode) { LockRelId relid = relation->rd_lockInfo.lockRelId; Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES); /* The relcache does the real work... */ RelationClose(relation); if (lockmode != NoLock) UnlockRelationId(&relid, lockmode); } /* ---------------- * heap_open - open a heap relation by relation OID * * This is essentially relation_open plus check that the relation * is not an index nor a composite type. (The caller should also * check that it's not a view before assuming it has storage.) * ---------------- */ Relation heap_open(Oid relationId, LOCKMODE lockmode) { Relation r; r = relation_open(relationId, lockmode); if (r->rd_rel->relkind == RELKIND_INDEX) ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), errmsg("\"%s\" is an index", RelationGetRelationName(r)))); else if (r->rd_rel->relkind == RELKIND_COMPOSITE_TYPE) ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), errmsg("\"%s\" is a composite type", RelationGetRelationName(r)))); return r; } /* ---------------- * heap_openrv - open a heap relation specified * by a RangeVar node * * As above, but relation is specified by a RangeVar. * ---------------- */ Relation heap_openrv(const RangeVar *relation, LOCKMODE lockmode) { Relation r; r = relation_openrv(relation, lockmode); if (r->rd_rel->relkind == RELKIND_INDEX) ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), errmsg("\"%s\" is an index", RelationGetRelationName(r)))); else if (r->rd_rel->relkind == RELKIND_COMPOSITE_TYPE) ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), errmsg("\"%s\" is a composite type", RelationGetRelationName(r)))); return r; } /* ---------------- * heap_beginscan - begin relation scan * * heap_beginscan_bm is an alternate entry point for setting up a HeapScanDesc * for a bitmap heap scan. Although that scan technology is really quite * unlike a standard seqscan, there is just enough commonality to make it * worth using the same data structure. * ---------------- */ HeapScanDesc heap_beginscan(Relation relation, Snapshot snapshot, int nkeys, ScanKey key) { return heap_beginscan_internal(relation, snapshot, nkeys, key, false); } HeapScanDesc heap_beginscan_bm(Relation relation, Snapshot snapshot, int nkeys, ScanKey key) { return heap_beginscan_internal(relation, snapshot, nkeys, key, true); } static HeapScanDesc heap_beginscan_internal(Relation relation, Snapshot snapshot, int nkeys, ScanKey key, bool is_bitmapscan) { HeapScanDesc scan; /* * increment relation ref count while scanning relation * * This is just to make really sure the relcache entry won't go away while * the scan has a pointer to it. Caller should be holding the rel open * anyway, so this is redundant in all normal scenarios... */ RelationIncrementReferenceCount(relation); /* * allocate and initialize scan descriptor */ scan = (HeapScanDesc) palloc(sizeof(HeapScanDescData)); scan->rs_rd = relation; scan->rs_snapshot = snapshot; scan->rs_nkeys = nkeys; scan->rs_bitmapscan = is_bitmapscan; scan->rs_strategy = NULL; /* set in initscan */ /* * we can use page-at-a-time mode if it's an MVCC-safe snapshot */ scan->rs_pageatatime = IsMVCCSnapshot(snapshot); /* we only need to set this up once */ scan->rs_ctup.t_tableOid = RelationGetRelid(relation); /* * we do this here instead of in initscan() because heap_rescan also calls * initscan() and we don't want to allocate memory again */ if (nkeys > 0) scan->rs_key = (ScanKey) palloc(sizeof(ScanKeyData) * nkeys); else scan->rs_key = NULL; initscan(scan, key); return scan; } /* ---------------- * heap_rescan - restart a relation scan * ---------------- */ void heap_rescan(HeapScanDesc scan, ScanKey key) { /* * unpin scan buffers */ if (BufferIsValid(scan->rs_cbuf)) ReleaseBuffer(scan->rs_cbuf); /* * reinitialize scan descriptor */ initscan(scan, key); } /* ---------------- * heap_endscan - end relation scan * * See how to integrate with index scans. * Check handling if reldesc caching. * ---------------- */ void heap_endscan(HeapScanDesc scan) { /* Note: no locking manipulations needed */ /* * unpin scan buffers */ if (BufferIsValid(scan->rs_cbuf)) ReleaseBuffer(scan->rs_cbuf); /* * decrement relation reference count and free scan descriptor storage */ RelationDecrementReferenceCount(scan->rs_rd); if (scan->rs_key) pfree(scan->rs_key); if (scan->rs_strategy != NULL) FreeAccessStrategy(scan->rs_strategy); pfree(scan); } /* ---------------- * heap_getnext - retrieve next tuple in scan * * Fix to work with index relations. * We don't return the buffer anymore, but you can get it from the * returned HeapTuple. * ---------------- */ #ifdef HEAPDEBUGALL #define HEAPDEBUG_1 \ elog(DEBUG2, "heap_getnext([%s,nkeys=%d],dir=%d) called", \ RelationGetRelationName(scan->rs_rd), scan->rs_nkeys, (int) direction) #define HEAPDEBUG_2 \ elog(DEBUG2, "heap_getnext returning EOS") #define HEAPDEBUG_3 \ elog(DEBUG2, "heap_getnext returning tuple") #else #define HEAPDEBUG_1 #define HEAPDEBUG_2 #define HEAPDEBUG_3 #endif /* !defined(HEAPDEBUGALL) */ HeapTuple heap_getnext(HeapScanDesc scan, ScanDirection direction) { /* Note: no locking manipulations needed */ HEAPDEBUG_1; /* heap_getnext( info ) */ if (scan->rs_pageatatime) heapgettup_pagemode(scan, direction, scan->rs_nkeys, scan->rs_key); else heapgettup(scan, direction, scan->rs_nkeys, scan->rs_key); if (scan->rs_ctup.t_data == NULL) { HEAPDEBUG_2; /* heap_getnext returning EOS */ return NULL; } /* * if we get here it means we have a new current scan tuple, so point to * the proper return buffer and return the tuple. */ HEAPDEBUG_3; /* heap_getnext returning tuple */ pgstat_count_heap_getnext(scan->rs_rd); return &(scan->rs_ctup); } /* * heap_fetch - retrieve tuple with given tid * * On entry, tuple->t_self is the TID to fetch. We pin the buffer holding * the tuple, fill in the remaining fields of *tuple, and check the tuple * against the specified snapshot. * * If successful (tuple found and passes snapshot time qual), then *userbuf * is set to the buffer holding the tuple and TRUE is returned. The caller * must unpin the buffer when done with the tuple. * * If the tuple is not found (ie, item number references a deleted slot), * then tuple->t_data is set to NULL and FALSE is returned. * * If the tuple is found but fails the time qual check, then FALSE is returned * but tuple->t_data is left pointing to the tuple. * * keep_buf determines what is done with the buffer in the FALSE-result cases. * When the caller specifies keep_buf = true, we retain the pin on the buffer * and return it in *userbuf (so the caller must eventually unpin it); when * keep_buf = false, the pin is released and *userbuf is set to InvalidBuffer. * * stats_relation is the relation to charge the heap_fetch operation against * for statistical purposes. (This could be the heap rel itself, an * associated index, or NULL to not count the fetch at all.) * * It is somewhat inconsistent that we ereport() on invalid block number but * return false on invalid item number. There are a couple of reasons though. * One is that the caller can relatively easily check the block number for * validity, but cannot check the item number without reading the page * himself. Another is that when we are following a t_ctid link, we can be * reasonably confident that the page number is valid (since VACUUM shouldn't * truncate off the destination page without having killed the referencing * tuple first), but the item number might well not be good. */ bool heap_fetch(Relation relation, Snapshot snapshot, HeapTuple tuple, Buffer *userbuf, bool keep_buf, Relation stats_relation) { /* Assume *userbuf is undefined on entry */ *userbuf = InvalidBuffer; return heap_release_fetch(relation, snapshot, tuple, userbuf, keep_buf, stats_relation); } /* * heap_release_fetch - retrieve tuple with given tid * * This has the same API as heap_fetch except that if *userbuf is not * InvalidBuffer on entry, that buffer will be released before reading * the new page. This saves a separate ReleaseBuffer step and hence * one entry into the bufmgr when looping through multiple fetches. * Also, if *userbuf is the same buffer that holds the target tuple, * we avoid bufmgr manipulation altogether. */ bool heap_release_fetch(Relation relation, Snapshot snapshot, HeapTuple tuple, Buffer *userbuf, bool keep_buf, Relation stats_relation) { ItemPointer tid = &(tuple->t_self); ItemId lp; Buffer buffer; PageHeader dp; OffsetNumber offnum; bool valid; /* * get the buffer from the relation descriptor. Note that this does a * buffer pin, and releases the old *userbuf if not InvalidBuffer. */ buffer = ReleaseAndReadBuffer(*userbuf, relation, ItemPointerGetBlockNumber(tid)); /* * Need share lock on buffer to examine tuple commit status. */ LockBuffer(buffer, BUFFER_LOCK_SHARE); dp = (PageHeader) BufferGetPage(buffer); /* * We'd better check for out-of-range offnum in case of VACUUM since the * TID was obtained. */ offnum = ItemPointerGetOffsetNumber(tid); if (offnum < FirstOffsetNumber || offnum > PageGetMaxOffsetNumber(dp)) { LockBuffer(buffer, BUFFER_LOCK_UNLOCK); if (keep_buf) *userbuf = buffer; else { ReleaseBuffer(buffer); *userbuf = InvalidBuffer; } tuple->t_data = NULL; return false; } /* * get the item line pointer corresponding to the requested tid */ lp = PageGetItemId(dp, offnum); /* * Must check for deleted tuple. */ if (!ItemIdIsUsed(lp)) { LockBuffer(buffer, BUFFER_LOCK_UNLOCK); if (keep_buf) *userbuf = buffer; else { ReleaseBuffer(buffer); *userbuf = InvalidBuffer; } tuple->t_data = NULL; return false; } /* * fill in *tuple fields */ tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp); tuple->t_len = ItemIdGetLength(lp); tuple->t_tableOid = RelationGetRelid(relation); /* * check time qualification of tuple, then release lock */ valid = HeapTupleSatisfiesVisibility(tuple, snapshot, buffer); LockBuffer(buffer, BUFFER_LOCK_UNLOCK); if (valid) { /* * All checks passed, so return the tuple as valid. Caller is now * responsible for releasing the buffer. */ *userbuf = buffer; /* Count the successful fetch against appropriate rel, if any */ if (stats_relation != NULL) pgstat_count_heap_fetch(stats_relation); return true; } /* Tuple failed time qual, but maybe caller wants to see it anyway. */ if (keep_buf) *userbuf = buffer; else { ReleaseBuffer(buffer); *userbuf = InvalidBuffer; } return false; } /* * heap_get_latest_tid - get the latest tid of a specified tuple * * Actually, this gets the latest version that is visible according to * the passed snapshot. You can pass SnapshotDirty to get the very latest, * possibly uncommitted version. * * *tid is both an input and an output parameter: it is updated to * show the latest version of the row. Note that it will not be changed * if no version of the row passes the snapshot test. */ void heap_get_latest_tid(Relation relation, Snapshot snapshot, ItemPointer tid) { BlockNumber blk; ItemPointerData ctid; TransactionId priorXmax; /* this is to avoid Assert failures on bad input */ if (!ItemPointerIsValid(tid)) return; /* * Since this can be called with user-supplied TID, don't trust the input * too much. (RelationGetNumberOfBlocks is an expensive check, so we * don't check t_ctid links again this way. Note that it would not do to * call it just once and save the result, either.) */ blk = ItemPointerGetBlockNumber(tid); if (blk >= RelationGetNumberOfBlocks(relation)) elog(ERROR, "block number %u is out of range for relation \"%s\"", blk, RelationGetRelationName(relation)); /* * Loop to chase down t_ctid links. At top of loop, ctid is the tuple we * need to examine, and *tid is the TID we will return if ctid turns out * to be bogus. * * Note that we will loop until we reach the end of the t_ctid chain. * Depending on the snapshot passed, there might be at most one visible * version of the row, but we don't try to optimize for that. */ ctid = *tid; priorXmax = InvalidTransactionId; /* cannot check first XMIN */ for (;;) { Buffer buffer; PageHeader dp; OffsetNumber offnum; ItemId lp; HeapTupleData tp; bool valid; /* * Read, pin, and lock the page. */ buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&ctid)); LockBuffer(buffer, BUFFER_LOCK_SHARE); dp = (PageHeader) BufferGetPage(buffer); /* * Check for bogus item number. This is not treated as an error * condition because it can happen while following a t_ctid link. We * just assume that the prior tid is OK and return it unchanged. */ offnum = ItemPointerGetOffsetNumber(&ctid); if (offnum < FirstOffsetNumber || offnum > PageGetMaxOffsetNumber(dp)) { UnlockReleaseBuffer(buffer); break; } lp = PageGetItemId(dp, offnum); if (!ItemIdIsUsed(lp)) { UnlockReleaseBuffer(buffer); break; } /* OK to access the tuple */ tp.t_self = ctid; tp.t_data = (HeapTupleHeader) PageGetItem(dp, lp); tp.t_len = ItemIdGetLength(lp); /* * After following a t_ctid link, we might arrive at an unrelated * tuple. Check for XMIN match. */ if (TransactionIdIsValid(priorXmax) && !TransactionIdEquals(priorXmax, HeapTupleHeaderGetXmin(tp.t_data))) { UnlockReleaseBuffer(buffer); break; } /* * Check time qualification of tuple; if visible, set it as the new * result candidate. */ valid = HeapTupleSatisfiesVisibility(&tp, snapshot, buffer); if (valid) *tid = ctid; /* * If there's a valid t_ctid link, follow it, else we're done. */ if ((tp.t_data->t_infomask & (HEAP_XMAX_INVALID | HEAP_IS_LOCKED)) || ItemPointerEquals(&tp.t_self, &tp.t_data->t_ctid)) { UnlockReleaseBuffer(buffer); break; } ctid = tp.t_data->t_ctid; priorXmax = HeapTupleHeaderGetXmax(tp.t_data); UnlockReleaseBuffer(buffer); } /* end of loop */ } /* * UpdateXmaxHintBits - update tuple hint bits after xmax transaction ends * * This is called after we have waited for the XMAX transaction to terminate. * If the transaction aborted, we guarantee the XMAX_INVALID hint bit will * be set on exit. If the transaction committed, we set the XMAX_COMMITTED * hint bit if possible --- but beware that that may not yet be possible, * if the transaction committed asynchronously. Hence callers should look * only at XMAX_INVALID. */ static void UpdateXmaxHintBits(HeapTupleHeader tuple, Buffer buffer, TransactionId xid) { Assert(TransactionIdEquals(HeapTupleHeaderGetXmax(tuple), xid)); if (!(tuple->t_infomask & (HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID))) { if (TransactionIdDidCommit(xid)) HeapTupleSetHintBits(tuple, buffer, HEAP_XMAX_COMMITTED, xid); else HeapTupleSetHintBits(tuple, buffer, HEAP_XMAX_INVALID, InvalidTransactionId); } } /* * heap_insert - insert tuple into a heap * * The new tuple is stamped with current transaction ID and the specified * command ID. * * If use_wal is false, the new tuple is not logged in WAL, even for a * non-temp relation. Safe usage of this behavior requires that we arrange * that all new tuples go into new pages not containing any tuples from other * transactions, and that the relation gets fsync'd before commit. * (See also heap_sync() comments) * * use_fsm is passed directly to RelationGetBufferForTuple, which see for * more info. * * Note that use_wal and use_fsm will be applied when inserting into the * heap's TOAST table, too, if the tuple requires any out-of-line data. * * The return value is the OID assigned to the tuple (either here or by the * caller), or InvalidOid if no OID. The header fields of *tup are updated * to match the stored tuple; in particular tup->t_self receives the actual * TID where the tuple was stored. But note that any toasting of fields * within the tuple data is NOT reflected into *tup. */ Oid heap_insert(Relation relation, HeapTuple tup, CommandId cid, bool use_wal, bool use_fsm) { TransactionId xid = GetCurrentTransactionId(); HeapTuple heaptup; Buffer buffer; if (relation->rd_rel->relhasoids) { #ifdef NOT_USED /* this is redundant with an Assert in HeapTupleSetOid */ Assert(tup->t_data->t_infomask & HEAP_HASOID); #endif /* * If the object id of this tuple has already been assigned, trust the * caller. There are a couple of ways this can happen. At initial db * creation, the backend program sets oids for tuples. When we define * an index, we set the oid. Finally, in the future, we may allow * users to set their own object ids in order to support a persistent * object store (objects need to contain pointers to one another). */ if (!OidIsValid(HeapTupleGetOid(tup))) HeapTupleSetOid(tup, GetNewOid(relation)); } else { /* check there is not space for an OID */ Assert(!(tup->t_data->t_infomask & HEAP_HASOID)); } tup->t_data->t_infomask &= ~(HEAP_XACT_MASK); tup->t_data->t_infomask |= HEAP_XMAX_INVALID; HeapTupleHeaderSetXmin(tup->t_data, xid); HeapTupleHeaderSetCmin(tup->t_data, cid); HeapTupleHeaderSetXmax(tup->t_data, 0); /* for cleanliness */ tup->t_tableOid = RelationGetRelid(relation); /* * If the new tuple is too big for storage or contains already toasted * out-of-line attributes from some other relation, invoke the toaster. * * Note: below this point, heaptup is the data we actually intend to store * into the relation; tup is the caller's original untoasted data. */ if (relation->rd_rel->relkind == RELKIND_TOASTVALUE) { /* toast table entries should never be recursively toasted */ Assert(!HeapTupleHasExternal(tup)); heaptup = tup; } else if (HeapTupleHasExternal(tup) || tup->t_len > TOAST_TUPLE_THRESHOLD) heaptup = toast_insert_or_update(relation, tup, NULL, use_wal, use_fsm); else heaptup = tup; /* Find buffer to insert this tuple into */ buffer = RelationGetBufferForTuple(relation, heaptup->t_len, InvalidBuffer, use_fsm); /* NO EREPORT(ERROR) from here till changes are logged */ START_CRIT_SECTION(); RelationPutHeapTuple(relation, buffer, heaptup); MarkBufferDirty(buffer); /* XLOG stuff */ if (use_wal && !relation->rd_istemp) { xl_heap_insert xlrec; xl_heap_header xlhdr; XLogRecPtr recptr; XLogRecData rdata[3]; Page page = BufferGetPage(buffer); uint8 info = XLOG_HEAP_INSERT; xlrec.target.node = relation->rd_node; xlrec.target.tid = heaptup->t_self; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapInsert; rdata[0].buffer = InvalidBuffer; rdata[0].next = &(rdata[1]); xlhdr.t_infomask2 = heaptup->t_data->t_infomask2; xlhdr.t_infomask = heaptup->t_data->t_infomask; xlhdr.t_hoff = heaptup->t_data->t_hoff; /* * note we mark rdata[1] as belonging to buffer; if XLogInsert decides * to write the whole page to the xlog, we don't need to store * xl_heap_header in the xlog. */ rdata[1].data = (char *) &xlhdr; rdata[1].len = SizeOfHeapHeader; rdata[1].buffer = buffer; rdata[1].buffer_std = true; rdata[1].next = &(rdata[2]); /* PG73FORMAT: write bitmap [+ padding] [+ oid] + data */ rdata[2].data = (char *) heaptup->t_data + offsetof(HeapTupleHeaderData, t_bits); rdata[2].len = heaptup->t_len - offsetof(HeapTupleHeaderData, t_bits); rdata[2].buffer = buffer; rdata[2].buffer_std = true; rdata[2].next = NULL; /* * If this is the single and first tuple on page, we can reinit the * page instead of restoring the whole thing. Set flag, and hide * buffer references from XLogInsert. */ if (ItemPointerGetOffsetNumber(&(heaptup->t_self)) == FirstOffsetNumber && PageGetMaxOffsetNumber(page) == FirstOffsetNumber) { info |= XLOG_HEAP_INIT_PAGE; rdata[1].buffer = rdata[2].buffer = InvalidBuffer; } recptr = XLogInsert(RM_HEAP_ID, info, rdata); PageSetLSN(page, recptr); PageSetTLI(page, ThisTimeLineID); } END_CRIT_SECTION(); UnlockReleaseBuffer(buffer); /* * If tuple is cachable, mark it for invalidation from the caches in case * we abort. Note it is OK to do this after releasing the buffer, because * the heaptup data structure is all in local memory, not in the shared * buffer. */ CacheInvalidateHeapTuple(relation, heaptup); pgstat_count_heap_insert(relation); /* * If heaptup is a private copy, release it. Don't forget to copy t_self * back to the caller's image, too. */ if (heaptup != tup) { tup->t_self = heaptup->t_self; heap_freetuple(heaptup); } return HeapTupleGetOid(tup); } /* * simple_heap_insert - insert a tuple * * Currently, this routine differs from heap_insert only in supplying * a default command ID and not allowing access to the speedup options. * * This should be used rather than using heap_insert directly in most places * where we are modifying system catalogs. */ Oid simple_heap_insert(Relation relation, HeapTuple tup) { return heap_insert(relation, tup, GetCurrentCommandId(), true, true); } /* * heap_delete - delete a tuple * * NB: do not call this directly unless you are prepared to deal with * concurrent-update conditions. Use simple_heap_delete instead. * * relation - table to be modified (caller must hold suitable lock) * tid - TID of tuple to be deleted * ctid - output parameter, used only for failure case (see below) * update_xmax - output parameter, used only for failure case (see below) * cid - delete command ID (used for visibility test, and stored into * cmax if successful) * crosscheck - if not InvalidSnapshot, also check tuple against this * wait - true if should wait for any conflicting update to commit/abort * * Normal, successful return value is HeapTupleMayBeUpdated, which * actually means we did delete it. Failure return codes are * HeapTupleSelfUpdated, HeapTupleUpdated, or HeapTupleBeingUpdated * (the last only possible if wait == false). * * In the failure cases, the routine returns the tuple's t_ctid and t_xmax. * If t_ctid is the same as tid, the tuple was deleted; if different, the * tuple was updated, and t_ctid is the location of the replacement tuple. * (t_xmax is needed to verify that the replacement tuple matches.) */ HTSU_Result heap_delete(Relation relation, ItemPointer tid, ItemPointer ctid, TransactionId *update_xmax, CommandId cid, Snapshot crosscheck, bool wait) { HTSU_Result result; TransactionId xid = GetCurrentTransactionId(); ItemId lp; HeapTupleData tp; PageHeader dp; Buffer buffer; bool have_tuple_lock = false; bool iscombo; Assert(ItemPointerIsValid(tid)); buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid)); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); dp = (PageHeader) BufferGetPage(buffer); lp = PageGetItemId(dp, ItemPointerGetOffsetNumber(tid)); tp.t_data = (HeapTupleHeader) PageGetItem(dp, lp); tp.t_len = ItemIdGetLength(lp); tp.t_self = *tid; l1: result = HeapTupleSatisfiesUpdate(tp.t_data, cid, buffer); if (result == HeapTupleInvisible) { UnlockReleaseBuffer(buffer); elog(ERROR, "attempted to delete invisible tuple"); } else if (result == HeapTupleBeingUpdated && wait) { TransactionId xwait; uint16 infomask; /* must copy state data before unlocking buffer */ xwait = HeapTupleHeaderGetXmax(tp.t_data); infomask = tp.t_data->t_infomask; LockBuffer(buffer, BUFFER_LOCK_UNLOCK); /* * Acquire tuple lock to establish our priority for the tuple (see * heap_lock_tuple). LockTuple will release us when we are * next-in-line for the tuple. * * If we are forced to "start over" below, we keep the tuple lock; * this arranges that we stay at the head of the line while rechecking * tuple state. */ if (!have_tuple_lock) { LockTuple(relation, &(tp.t_self), ExclusiveLock); have_tuple_lock = true; } /* * Sleep until concurrent transaction ends. Note that we don't care * if the locker has an exclusive or shared lock, because we need * exclusive. */ if (infomask & HEAP_XMAX_IS_MULTI) { /* wait for multixact */ MultiXactIdWait((MultiXactId) xwait); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); /* * If xwait had just locked the tuple then some other xact could * update this tuple before we get to this point. Check for xmax * change, and start over if so. */ if (!(tp.t_data->t_infomask & HEAP_XMAX_IS_MULTI) || !TransactionIdEquals(HeapTupleHeaderGetXmax(tp.t_data), xwait)) goto l1; /* * You might think the multixact is necessarily done here, but not * so: it could have surviving members, namely our own xact or * other subxacts of this backend. It is legal for us to delete * the tuple in either case, however (the latter case is * essentially a situation of upgrading our former shared lock to * exclusive). We don't bother changing the on-disk hint bits * since we are about to overwrite the xmax altogether. */ } else { /* wait for regular transaction to end */ XactLockTableWait(xwait); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); /* * xwait is done, but if xwait had just locked the tuple then some * other xact could update this tuple before we get to this point. * Check for xmax change, and start over if so. */ if ((tp.t_data->t_infomask & HEAP_XMAX_IS_MULTI) || !TransactionIdEquals(HeapTupleHeaderGetXmax(tp.t_data), xwait)) goto l1; /* Otherwise check if it committed or aborted */ UpdateXmaxHintBits(tp.t_data, buffer, xwait); } /* * We may overwrite if previous xmax aborted, or if it committed but * only locked the tuple without updating it. */ if (tp.t_data->t_infomask & (HEAP_XMAX_INVALID | HEAP_IS_LOCKED)) result = HeapTupleMayBeUpdated; else result = HeapTupleUpdated; } if (crosscheck != InvalidSnapshot && result == HeapTupleMayBeUpdated) { /* Perform additional check for serializable RI updates */ if (!HeapTupleSatisfiesVisibility(&tp, crosscheck, buffer)) result = HeapTupleUpdated; } if (result != HeapTupleMayBeUpdated) { Assert(result == HeapTupleSelfUpdated || result == HeapTupleUpdated || result == HeapTupleBeingUpdated); Assert(!(tp.t_data->t_infomask & HEAP_XMAX_INVALID)); *ctid = tp.t_data->t_ctid; *update_xmax = HeapTupleHeaderGetXmax(tp.t_data); UnlockReleaseBuffer(buffer); if (have_tuple_lock) UnlockTuple(relation, &(tp.t_self), ExclusiveLock); return result; } /* replace cid with a combo cid if necessary */ HeapTupleHeaderAdjustCmax(tp.t_data, &cid, &iscombo); START_CRIT_SECTION(); /* store transaction information of xact deleting the tuple */ tp.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | HEAP_XMAX_IS_MULTI | HEAP_IS_LOCKED | HEAP_MOVED); HeapTupleHeaderSetXmax(tp.t_data, xid); HeapTupleHeaderSetCmax(tp.t_data, cid, iscombo); /* Make sure there is no forward chain link in t_ctid */ tp.t_data->t_ctid = tp.t_self; MarkBufferDirty(buffer); /* XLOG stuff */ if (!relation->rd_istemp) { xl_heap_delete xlrec; XLogRecPtr recptr; XLogRecData rdata[2]; xlrec.target.node = relation->rd_node; xlrec.target.tid = tp.t_self; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapDelete; rdata[0].buffer = InvalidBuffer; rdata[0].next = &(rdata[1]); rdata[1].data = NULL; rdata[1].len = 0; rdata[1].buffer = buffer; rdata[1].buffer_std = true; rdata[1].next = NULL; recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_DELETE, rdata); PageSetLSN(dp, recptr); PageSetTLI(dp, ThisTimeLineID); } END_CRIT_SECTION(); LockBuffer(buffer, BUFFER_LOCK_UNLOCK); /* * If the tuple has toasted out-of-line attributes, we need to delete * those items too. We have to do this before releasing the buffer * because we need to look at the contents of the tuple, but it's OK to * release the content lock on the buffer first. */ if (relation->rd_rel->relkind == RELKIND_TOASTVALUE) { /* toast table entries should never be recursively toasted */ Assert(!HeapTupleHasExternal(&tp)); } else if (HeapTupleHasExternal(&tp)) toast_delete(relation, &tp); /* * Mark tuple for invalidation from system caches at next command * boundary. We have to do this before releasing the buffer because we * need to look at the contents of the tuple. */ CacheInvalidateHeapTuple(relation, &tp); /* Now we can release the buffer */ ReleaseBuffer(buffer); /* * Release the lmgr tuple lock, if we had it. */ if (have_tuple_lock) UnlockTuple(relation, &(tp.t_self), ExclusiveLock); pgstat_count_heap_delete(relation); return HeapTupleMayBeUpdated; } /* * simple_heap_delete - delete a tuple * * This routine may be used to delete a tuple when concurrent updates of * the target tuple are not expected (for example, because we have a lock * on the relation associated with the tuple). Any failure is reported * via ereport(). */ void simple_heap_delete(Relation relation, ItemPointer tid) { HTSU_Result result; ItemPointerData update_ctid; TransactionId update_xmax; result = heap_delete(relation, tid, &update_ctid, &update_xmax, GetCurrentCommandId(), InvalidSnapshot, true /* wait for commit */ ); switch (result) { case HeapTupleSelfUpdated: /* Tuple was already updated in current command? */ elog(ERROR, "tuple already updated by self"); break; case HeapTupleMayBeUpdated: /* done successfully */ break; case HeapTupleUpdated: elog(ERROR, "tuple concurrently updated"); break; default: elog(ERROR, "unrecognized heap_delete status: %u", result); break; } } /* * heap_update - replace a tuple * * NB: do not call this directly unless you are prepared to deal with * concurrent-update conditions. Use simple_heap_update instead. * * relation - table to be modified (caller must hold suitable lock) * otid - TID of old tuple to be replaced * newtup - newly constructed tuple data to store * ctid - output parameter, used only for failure case (see below) * update_xmax - output parameter, used only for failure case (see below) * cid - update command ID (used for visibility test, and stored into * cmax/cmin if successful) * crosscheck - if not InvalidSnapshot, also check old tuple against this * wait - true if should wait for any conflicting update to commit/abort * * Normal, successful return value is HeapTupleMayBeUpdated, which * actually means we *did* update it. Failure return codes are * HeapTupleSelfUpdated, HeapTupleUpdated, or HeapTupleBeingUpdated * (the last only possible if wait == false). * * On success, the header fields of *newtup are updated to match the new * stored tuple; in particular, newtup->t_self is set to the TID where the * new tuple was inserted. However, any TOAST changes in the new tuple's * data are not reflected into *newtup. * * In the failure cases, the routine returns the tuple's t_ctid and t_xmax. * If t_ctid is the same as otid, the tuple was deleted; if different, the * tuple was updated, and t_ctid is the location of the replacement tuple. * (t_xmax is needed to verify that the replacement tuple matches.) */ HTSU_Result heap_update(Relation relation, ItemPointer otid, HeapTuple newtup, ItemPointer ctid, TransactionId *update_xmax, CommandId cid, Snapshot crosscheck, bool wait) { HTSU_Result result; TransactionId xid = GetCurrentTransactionId(); ItemId lp; HeapTupleData oldtup; HeapTuple heaptup; PageHeader dp; Buffer buffer, newbuf; bool need_toast, already_marked; Size newtupsize, pagefree; bool have_tuple_lock = false; bool iscombo; Assert(ItemPointerIsValid(otid)); buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(otid)); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); dp = (PageHeader) BufferGetPage(buffer); lp = PageGetItemId(dp, ItemPointerGetOffsetNumber(otid)); oldtup.t_data = (HeapTupleHeader) PageGetItem(dp, lp); oldtup.t_len = ItemIdGetLength(lp); oldtup.t_self = *otid; /* * Note: beyond this point, use oldtup not otid to refer to old tuple. * otid may very well point at newtup->t_self, which we will overwrite * with the new tuple's location, so there's great risk of confusion if we * use otid anymore. */ l2: result = HeapTupleSatisfiesUpdate(oldtup.t_data, cid, buffer); if (result == HeapTupleInvisible) { UnlockReleaseBuffer(buffer); elog(ERROR, "attempted to update invisible tuple"); } else if (result == HeapTupleBeingUpdated && wait) { TransactionId xwait; uint16 infomask; /* must copy state data before unlocking buffer */ xwait = HeapTupleHeaderGetXmax(oldtup.t_data); infomask = oldtup.t_data->t_infomask; LockBuffer(buffer, BUFFER_LOCK_UNLOCK); /* * Acquire tuple lock to establish our priority for the tuple (see * heap_lock_tuple). LockTuple will release us when we are * next-in-line for the tuple. * * If we are forced to "start over" below, we keep the tuple lock; * this arranges that we stay at the head of the line while rechecking * tuple state. */ if (!have_tuple_lock) { LockTuple(relation, &(oldtup.t_self), ExclusiveLock); have_tuple_lock = true; } /* * Sleep until concurrent transaction ends. Note that we don't care * if the locker has an exclusive or shared lock, because we need * exclusive. */ if (infomask & HEAP_XMAX_IS_MULTI) { /* wait for multixact */ MultiXactIdWait((MultiXactId) xwait); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); /* * If xwait had just locked the tuple then some other xact could * update this tuple before we get to this point. Check for xmax * change, and start over if so. */ if (!(oldtup.t_data->t_infomask & HEAP_XMAX_IS_MULTI) || !TransactionIdEquals(HeapTupleHeaderGetXmax(oldtup.t_data), xwait)) goto l2; /* * You might think the multixact is necessarily done here, but not * so: it could have surviving members, namely our own xact or * other subxacts of this backend. It is legal for us to update * the tuple in either case, however (the latter case is * essentially a situation of upgrading our former shared lock to * exclusive). We don't bother changing the on-disk hint bits * since we are about to overwrite the xmax altogether. */ } else { /* wait for regular transaction to end */ XactLockTableWait(xwait); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); /* * xwait is done, but if xwait had just locked the tuple then some * other xact could update this tuple before we get to this point. * Check for xmax change, and start over if so. */ if ((oldtup.t_data->t_infomask & HEAP_XMAX_IS_MULTI) || !TransactionIdEquals(HeapTupleHeaderGetXmax(oldtup.t_data), xwait)) goto l2; /* Otherwise check if it committed or aborted */ UpdateXmaxHintBits(oldtup.t_data, buffer, xwait); } /* * We may overwrite if previous xmax aborted, or if it committed but * only locked the tuple without updating it. */ if (oldtup.t_data->t_infomask & (HEAP_XMAX_INVALID | HEAP_IS_LOCKED)) result = HeapTupleMayBeUpdated; else result = HeapTupleUpdated; } if (crosscheck != InvalidSnapshot && result == HeapTupleMayBeUpdated) { /* Perform additional check for serializable RI updates */ if (!HeapTupleSatisfiesVisibility(&oldtup, crosscheck, buffer)) result = HeapTupleUpdated; } if (result != HeapTupleMayBeUpdated) { Assert(result == HeapTupleSelfUpdated || result == HeapTupleUpdated || result == HeapTupleBeingUpdated); Assert(!(oldtup.t_data->t_infomask & HEAP_XMAX_INVALID)); *ctid = oldtup.t_data->t_ctid; *update_xmax = HeapTupleHeaderGetXmax(oldtup.t_data); UnlockReleaseBuffer(buffer); if (have_tuple_lock) UnlockTuple(relation, &(oldtup.t_self), ExclusiveLock); return result; } /* Fill in OID and transaction status data for newtup */ if (relation->rd_rel->relhasoids) { #ifdef NOT_USED /* this is redundant with an Assert in HeapTupleSetOid */ Assert(newtup->t_data->t_infomask & HEAP_HASOID); #endif HeapTupleSetOid(newtup, HeapTupleGetOid(&oldtup)); } else { /* check there is not space for an OID */ Assert(!(newtup->t_data->t_infomask & HEAP_HASOID)); } newtup->t_data->t_infomask &= ~(HEAP_XACT_MASK); newtup->t_data->t_infomask |= (HEAP_XMAX_INVALID | HEAP_UPDATED); HeapTupleHeaderSetXmin(newtup->t_data, xid); HeapTupleHeaderSetCmin(newtup->t_data, cid); HeapTupleHeaderSetXmax(newtup->t_data, 0); /* for cleanliness */ /* * Replace cid with a combo cid if necessary. Note that we already put * the plain cid into the new tuple. */ HeapTupleHeaderAdjustCmax(oldtup.t_data, &cid, &iscombo); /* * If the toaster needs to be activated, OR if the new tuple will not fit * on the same page as the old, then we need to release the content lock * (but not the pin!) on the old tuple's buffer while we are off doing * TOAST and/or table-file-extension work. We must mark the old tuple to * show that it's already being updated, else other processes may try to * update it themselves. * * We need to invoke the toaster if there are already any out-of-line * toasted values present, or if the new tuple is over-threshold. */ if (relation->rd_rel->relkind == RELKIND_TOASTVALUE) { /* toast table entries should never be recursively toasted */ Assert(!HeapTupleHasExternal(&oldtup)); Assert(!HeapTupleHasExternal(newtup)); need_toast = false; } else need_toast = (HeapTupleHasExternal(&oldtup) || HeapTupleHasExternal(newtup) || newtup->t_len > TOAST_TUPLE_THRESHOLD); pagefree = PageGetFreeSpace((Page) dp); newtupsize = MAXALIGN(newtup->t_len); if (need_toast || newtupsize > pagefree) { oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | HEAP_XMAX_IS_MULTI | HEAP_IS_LOCKED | HEAP_MOVED); HeapTupleHeaderSetXmax(oldtup.t_data, xid); HeapTupleHeaderSetCmax(oldtup.t_data, cid, iscombo); /* temporarily make it look not-updated */ oldtup.t_data->t_ctid = oldtup.t_self; already_marked = true; LockBuffer(buffer, BUFFER_LOCK_UNLOCK); /* * Let the toaster do its thing, if needed. * * Note: below this point, heaptup is the data we actually intend to * store into the relation; newtup is the caller's original untoasted * data. */ if (need_toast) { /* Note we always use WAL and FSM during updates */ heaptup = toast_insert_or_update(relation, newtup, &oldtup, true, true); newtupsize = MAXALIGN(heaptup->t_len); } else heaptup = newtup; /* * Now, do we need a new page for the tuple, or not? This is a bit * tricky since someone else could have added tuples to the page while * we weren't looking. We have to recheck the available space after * reacquiring the buffer lock. But don't bother to do that if the * former amount of free space is still not enough; it's unlikely * there's more free now than before. * * What's more, if we need to get a new page, we will need to acquire * buffer locks on both old and new pages. To avoid deadlock against * some other backend trying to get the same two locks in the other * order, we must be consistent about the order we get the locks in. * We use the rule "lock the lower-numbered page of the relation * first". To implement this, we must do RelationGetBufferForTuple * while not holding the lock on the old page, and we must rely on it * to get the locks on both pages in the correct order. */ if (newtupsize > pagefree) { /* Assume there's no chance to put heaptup on same page. */ newbuf = RelationGetBufferForTuple(relation, heaptup->t_len, buffer, true); } else { /* Re-acquire the lock on the old tuple's page. */ LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); /* Re-check using the up-to-date free space */ pagefree = PageGetFreeSpace((Page) dp); if (newtupsize > pagefree) { /* * Rats, it doesn't fit anymore. We must now unlock and * relock to avoid deadlock. Fortunately, this path should * seldom be taken. */ LockBuffer(buffer, BUFFER_LOCK_UNLOCK); newbuf = RelationGetBufferForTuple(relation, heaptup->t_len, buffer, true); } else { /* OK, it fits here, so we're done. */ newbuf = buffer; } } } else { /* No TOAST work needed, and it'll fit on same page */ already_marked = false; newbuf = buffer; heaptup = newtup; } /* * At this point newbuf and buffer are both pinned and locked, and newbuf * has enough space for the new tuple. If they are the same buffer, only * one pin is held. */ /* NO EREPORT(ERROR) from here till changes are logged */ START_CRIT_SECTION(); RelationPutHeapTuple(relation, newbuf, heaptup); /* insert new tuple */ if (!already_marked) { oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | HEAP_XMAX_IS_MULTI | HEAP_IS_LOCKED | HEAP_MOVED); HeapTupleHeaderSetXmax(oldtup.t_data, xid); HeapTupleHeaderSetCmax(oldtup.t_data, cid, iscombo); } /* record address of new tuple in t_ctid of old one */ oldtup.t_data->t_ctid = heaptup->t_self; if (newbuf != buffer) MarkBufferDirty(newbuf); MarkBufferDirty(buffer); /* XLOG stuff */ if (!relation->rd_istemp) { XLogRecPtr recptr = log_heap_update(relation, buffer, oldtup.t_self, newbuf, heaptup, false); if (newbuf != buffer) { PageSetLSN(BufferGetPage(newbuf), recptr); PageSetTLI(BufferGetPage(newbuf), ThisTimeLineID); } PageSetLSN(BufferGetPage(buffer), recptr); PageSetTLI(BufferGetPage(buffer), ThisTimeLineID); } END_CRIT_SECTION(); if (newbuf != buffer) LockBuffer(newbuf, BUFFER_LOCK_UNLOCK); LockBuffer(buffer, BUFFER_LOCK_UNLOCK); /* * Mark old tuple for invalidation from system caches at next command * boundary. We have to do this before releasing the buffer because we * need to look at the contents of the tuple. */ CacheInvalidateHeapTuple(relation, &oldtup); /* Now we can release the buffer(s) */ if (newbuf != buffer) ReleaseBuffer(newbuf); ReleaseBuffer(buffer); /* * If new tuple is cachable, mark it for invalidation from the caches in * case we abort. Note it is OK to do this after releasing the buffer, * because the heaptup data structure is all in local memory, not in the * shared buffer. */ CacheInvalidateHeapTuple(relation, heaptup); /* * Release the lmgr tuple lock, if we had it. */ if (have_tuple_lock) UnlockTuple(relation, &(oldtup.t_self), ExclusiveLock); pgstat_count_heap_update(relation); /* * If heaptup is a private copy, release it. Don't forget to copy t_self * back to the caller's image, too. */ if (heaptup != newtup) { newtup->t_self = heaptup->t_self; heap_freetuple(heaptup); } return HeapTupleMayBeUpdated; } /* * simple_heap_update - replace a tuple * * This routine may be used to update a tuple when concurrent updates of * the target tuple are not expected (for example, because we have a lock * on the relation associated with the tuple). Any failure is reported * via ereport(). */ void simple_heap_update(Relation relation, ItemPointer otid, HeapTuple tup) { HTSU_Result result; ItemPointerData update_ctid; TransactionId update_xmax; result = heap_update(relation, otid, tup, &update_ctid, &update_xmax, GetCurrentCommandId(), InvalidSnapshot, true /* wait for commit */ ); switch (result) { case HeapTupleSelfUpdated: /* Tuple was already updated in current command? */ elog(ERROR, "tuple already updated by self"); break; case HeapTupleMayBeUpdated: /* done successfully */ break; case HeapTupleUpdated: elog(ERROR, "tuple concurrently updated"); break; default: elog(ERROR, "unrecognized heap_update status: %u", result); break; } } /* * heap_lock_tuple - lock a tuple in shared or exclusive mode * * Note that this acquires a buffer pin, which the caller must release. * * Input parameters: * relation: relation containing tuple (caller must hold suitable lock) * tuple->t_self: TID of tuple to lock (rest of struct need not be valid) * cid: current command ID (used for visibility test, and stored into * tuple's cmax if lock is successful) * mode: indicates if shared or exclusive tuple lock is desired * nowait: if true, ereport rather than blocking if lock not available * * Output parameters: * *tuple: all fields filled in * *buffer: set to buffer holding tuple (pinned but not locked at exit) * *ctid: set to tuple's t_ctid, but only in failure cases * *update_xmax: set to tuple's xmax, but only in failure cases * * Function result may be: * HeapTupleMayBeUpdated: lock was successfully acquired * HeapTupleSelfUpdated: lock failed because tuple updated by self * HeapTupleUpdated: lock failed because tuple updated by other xact * * In the failure cases, the routine returns the tuple's t_ctid and t_xmax. * If t_ctid is the same as t_self, the tuple was deleted; if different, the * tuple was updated, and t_ctid is the location of the replacement tuple. * (t_xmax is needed to verify that the replacement tuple matches.) * * * NOTES: because the shared-memory lock table is of finite size, but users * could reasonably want to lock large numbers of tuples, we do not rely on * the standard lock manager to store tuple-level locks over the long term. * Instead, a tuple is marked as locked by setting the current transaction's * XID as its XMAX, and setting additional infomask bits to distinguish this * usage from the more normal case of having deleted the tuple. When * multiple transactions concurrently share-lock a tuple, the first locker's * XID is replaced in XMAX with a MultiTransactionId representing the set of * XIDs currently holding share-locks. * * When it is necessary to wait for a tuple-level lock to be released, the * basic delay is provided by XactLockTableWait or MultiXactIdWait on the * contents of the tuple's XMAX. However, that mechanism will release all * waiters concurrently, so there would be a race condition as to which * waiter gets the tuple, potentially leading to indefinite starvation of * some waiters. The possibility of share-locking makes the problem much * worse --- a steady stream of share-lockers can easily block an exclusive * locker forever. To provide more reliable semantics about who gets a * tuple-level lock first, we use the standard lock manager. The protocol * for waiting for a tuple-level lock is really * LockTuple() * XactLockTableWait() * mark tuple as locked by me * UnlockTuple() * When there are multiple waiters, arbitration of who is to get the lock next * is provided by LockTuple(). However, at most one tuple-level lock will * be held or awaited per backend at any time, so we don't risk overflow * of the lock table. Note that incoming share-lockers are required to * do LockTuple as well, if there is any conflict, to ensure that they don't * starve out waiting exclusive-lockers. However, if there is not any active * conflict for a tuple, we don't incur any extra overhead. */ HTSU_Result heap_lock_tuple(Relation relation, HeapTuple tuple, Buffer *buffer, ItemPointer ctid, TransactionId *update_xmax, CommandId cid, LockTupleMode mode, bool nowait) { HTSU_Result result; ItemPointer tid = &(tuple->t_self); ItemId lp; PageHeader dp; TransactionId xid; TransactionId xmax; uint16 old_infomask; uint16 new_infomask; LOCKMODE tuple_lock_type; bool have_tuple_lock = false; tuple_lock_type = (mode == LockTupleShared) ? ShareLock : ExclusiveLock; *buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid)); LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE); dp = (PageHeader) BufferGetPage(*buffer); lp = PageGetItemId(dp, ItemPointerGetOffsetNumber(tid)); Assert(ItemIdIsUsed(lp)); tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp); tuple->t_len = ItemIdGetLength(lp); tuple->t_tableOid = RelationGetRelid(relation); l3: result = HeapTupleSatisfiesUpdate(tuple->t_data, cid, *buffer); if (result == HeapTupleInvisible) { UnlockReleaseBuffer(*buffer); elog(ERROR, "attempted to lock invisible tuple"); } else if (result == HeapTupleBeingUpdated) { TransactionId xwait; uint16 infomask; /* must copy state data before unlocking buffer */ xwait = HeapTupleHeaderGetXmax(tuple->t_data); infomask = tuple->t_data->t_infomask; LockBuffer(*buffer, BUFFER_LOCK_UNLOCK); /* * If we wish to acquire share lock, and the tuple is already * share-locked by a multixact that includes any subtransaction of the * current top transaction, then we effectively hold the desired lock * already. We *must* succeed without trying to take the tuple lock, * else we will deadlock against anyone waiting to acquire exclusive * lock. We don't need to make any state changes in this case. */ if (mode == LockTupleShared && (infomask & HEAP_XMAX_IS_MULTI) && MultiXactIdIsCurrent((MultiXactId) xwait)) { Assert(infomask & HEAP_XMAX_SHARED_LOCK); /* Probably can't hold tuple lock here, but may as well check */ if (have_tuple_lock) UnlockTuple(relation, tid, tuple_lock_type); return HeapTupleMayBeUpdated; } /* * Acquire tuple lock to establish our priority for the tuple. * LockTuple will release us when we are next-in-line for the tuple. * We must do this even if we are share-locking. * * If we are forced to "start over" below, we keep the tuple lock; * this arranges that we stay at the head of the line while rechecking * tuple state. */ if (!have_tuple_lock) { if (nowait) { if (!ConditionalLockTuple(relation, tid, tuple_lock_type)) ereport(ERROR, (errcode(ERRCODE_LOCK_NOT_AVAILABLE), errmsg("could not obtain lock on row in relation \"%s\"", RelationGetRelationName(relation)))); } else LockTuple(relation, tid, tuple_lock_type); have_tuple_lock = true; } if (mode == LockTupleShared && (infomask & HEAP_XMAX_SHARED_LOCK)) { /* * Acquiring sharelock when there's at least one sharelocker * already. We need not wait for him/them to complete. */ LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE); /* * Make sure it's still a shared lock, else start over. (It's OK * if the ownership of the shared lock has changed, though.) */ if (!(tuple->t_data->t_infomask & HEAP_XMAX_SHARED_LOCK)) goto l3; } else if (infomask & HEAP_XMAX_IS_MULTI) { /* wait for multixact to end */ if (nowait) { if (!ConditionalMultiXactIdWait((MultiXactId) xwait)) ereport(ERROR, (errcode(ERRCODE_LOCK_NOT_AVAILABLE), errmsg("could not obtain lock on row in relation \"%s\"", RelationGetRelationName(relation)))); } else MultiXactIdWait((MultiXactId) xwait); LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE); /* * If xwait had just locked the tuple then some other xact could * update this tuple before we get to this point. Check for xmax * change, and start over if so. */ if (!(tuple->t_data->t_infomask & HEAP_XMAX_IS_MULTI) || !TransactionIdEquals(HeapTupleHeaderGetXmax(tuple->t_data), xwait)) goto l3; /* * You might think the multixact is necessarily done here, but not * so: it could have surviving members, namely our own xact or * other subxacts of this backend. It is legal for us to lock the * tuple in either case, however. We don't bother changing the * on-disk hint bits since we are about to overwrite the xmax * altogether. */ } else { /* wait for regular transaction to end */ if (nowait) { if (!ConditionalXactLockTableWait(xwait)) ereport(ERROR, (errcode(ERRCODE_LOCK_NOT_AVAILABLE), errmsg("could not obtain lock on row in relation \"%s\"", RelationGetRelationName(relation)))); } else XactLockTableWait(xwait); LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE); /* * xwait is done, but if xwait had just locked the tuple then some * other xact could update this tuple before we get to this point. * Check for xmax change, and start over if so. */ if ((tuple->t_data->t_infomask & HEAP_XMAX_IS_MULTI) || !TransactionIdEquals(HeapTupleHeaderGetXmax(tuple->t_data), xwait)) goto l3; /* Otherwise check if it committed or aborted */ UpdateXmaxHintBits(tuple->t_data, *buffer, xwait); } /* * We may lock if previous xmax aborted, or if it committed but only * locked the tuple without updating it. The case where we didn't * wait because we are joining an existing shared lock is correctly * handled, too. */ if (tuple->t_data->t_infomask & (HEAP_XMAX_INVALID | HEAP_IS_LOCKED)) result = HeapTupleMayBeUpdated; else result = HeapTupleUpdated; } if (result != HeapTupleMayBeUpdated) { Assert(result == HeapTupleSelfUpdated || result == HeapTupleUpdated); Assert(!(tuple->t_data->t_infomask & HEAP_XMAX_INVALID)); *ctid = tuple->t_data->t_ctid; *update_xmax = HeapTupleHeaderGetXmax(tuple->t_data); LockBuffer(*buffer, BUFFER_LOCK_UNLOCK); if (have_tuple_lock) UnlockTuple(relation, tid, tuple_lock_type); return result; } /* * We might already hold the desired lock (or stronger), possibly under * a different subtransaction of the current top transaction. If so, * there is no need to change state or issue a WAL record. We already * handled the case where this is true for xmax being a MultiXactId, * so now check for cases where it is a plain TransactionId. * * Note in particular that this covers the case where we already hold * exclusive lock on the tuple and the caller only wants shared lock. * It would certainly not do to give up the exclusive lock. */ xmax = HeapTupleHeaderGetXmax(tuple->t_data); old_infomask = tuple->t_data->t_infomask; if (!(old_infomask & (HEAP_XMAX_INVALID | HEAP_XMAX_COMMITTED | HEAP_XMAX_IS_MULTI)) && (mode == LockTupleShared ? (old_infomask & HEAP_IS_LOCKED) : (old_infomask & HEAP_XMAX_EXCL_LOCK)) && TransactionIdIsCurrentTransactionId(xmax)) { LockBuffer(*buffer, BUFFER_LOCK_UNLOCK); /* Probably can't hold tuple lock here, but may as well check */ if (have_tuple_lock) UnlockTuple(relation, tid, tuple_lock_type); return HeapTupleMayBeUpdated; } /* * Compute the new xmax and infomask to store into the tuple. Note we do * not modify the tuple just yet, because that would leave it in the wrong * state if multixact.c elogs. */ xid = GetCurrentTransactionId(); new_infomask = old_infomask & ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | HEAP_XMAX_IS_MULTI | HEAP_IS_LOCKED | HEAP_MOVED); if (mode == LockTupleShared) { /* * If this is the first acquisition of a shared lock in the current * transaction, set my per-backend OldestMemberMXactId setting. We can * be certain that the transaction will never become a member of any * older MultiXactIds than that. (We have to do this even if we end * up just using our own TransactionId below, since some other backend * could incorporate our XID into a MultiXact immediately afterwards.) */ MultiXactIdSetOldestMember(); new_infomask |= HEAP_XMAX_SHARED_LOCK; /* * Check to see if we need a MultiXactId because there are multiple * lockers. * * HeapTupleSatisfiesUpdate will have set the HEAP_XMAX_INVALID bit if * the xmax was a MultiXactId but it was not running anymore. There is * a race condition, which is that the MultiXactId may have finished * since then, but that uncommon case is handled within * MultiXactIdExpand. * * There is a similar race condition possible when the old xmax was a * regular TransactionId. We test TransactionIdIsInProgress again * just to narrow the window, but it's still possible to end up * creating an unnecessary MultiXactId. Fortunately this is harmless. */ if (!(old_infomask & (HEAP_XMAX_INVALID | HEAP_XMAX_COMMITTED))) { if (old_infomask & HEAP_XMAX_IS_MULTI) { /* * If the XMAX is already a MultiXactId, then we need to * expand it to include our own TransactionId. */ xid = MultiXactIdExpand((MultiXactId) xmax, xid); new_infomask |= HEAP_XMAX_IS_MULTI; } else if (TransactionIdIsInProgress(xmax)) { /* * If the XMAX is a valid TransactionId, then we need to * create a new MultiXactId that includes both the old * locker and our own TransactionId. */ xid = MultiXactIdCreate(xmax, xid); new_infomask |= HEAP_XMAX_IS_MULTI; } else { /* * Can get here iff HeapTupleSatisfiesUpdate saw the old xmax * as running, but it finished before * TransactionIdIsInProgress() got to run. Treat it like * there's no locker in the tuple. */ } } else { /* * There was no previous locker, so just insert our own * TransactionId. */ } } else { /* We want an exclusive lock on the tuple */ new_infomask |= HEAP_XMAX_EXCL_LOCK; } START_CRIT_SECTION(); /* * Store transaction information of xact locking the tuple. * * Note: Cmax is meaningless in this context, so don't set it; this * avoids possibly generating a useless combo CID. */ tuple->t_data->t_infomask = new_infomask; HeapTupleHeaderSetXmax(tuple->t_data, xid); /* Make sure there is no forward chain link in t_ctid */ tuple->t_data->t_ctid = *tid; MarkBufferDirty(*buffer); /* * XLOG stuff. You might think that we don't need an XLOG record because * there is no state change worth restoring after a crash. You would be * wrong however: we have just written either a TransactionId or a * MultiXactId that may never have been seen on disk before, and we need * to make sure that there are XLOG entries covering those ID numbers. * Else the same IDs might be re-used after a crash, which would be * disastrous if this page made it to disk before the crash. Essentially * we have to enforce the WAL log-before-data rule even in this case. * (Also, in a PITR log-shipping or 2PC environment, we have to have XLOG * entries for everything anyway.) */ if (!relation->rd_istemp) { xl_heap_lock xlrec; XLogRecPtr recptr; XLogRecData rdata[2]; xlrec.target.node = relation->rd_node; xlrec.target.tid = tuple->t_self; xlrec.locking_xid = xid; xlrec.xid_is_mxact = ((new_infomask & HEAP_XMAX_IS_MULTI) != 0); xlrec.shared_lock = (mode == LockTupleShared); rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapLock; rdata[0].buffer = InvalidBuffer; rdata[0].next = &(rdata[1]); rdata[1].data = NULL; rdata[1].len = 0; rdata[1].buffer = *buffer; rdata[1].buffer_std = true; rdata[1].next = NULL; recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_LOCK, rdata); PageSetLSN(dp, recptr); PageSetTLI(dp, ThisTimeLineID); } END_CRIT_SECTION(); LockBuffer(*buffer, BUFFER_LOCK_UNLOCK); /* * Now that we have successfully marked the tuple as locked, we can * release the lmgr tuple lock, if we had it. */ if (have_tuple_lock) UnlockTuple(relation, tid, tuple_lock_type); return HeapTupleMayBeUpdated; } /* * heap_inplace_update - update a tuple "in place" (ie, overwrite it) * * Overwriting violates both MVCC and transactional safety, so the uses * of this function in Postgres are extremely limited. Nonetheless we * find some places to use it. * * The tuple cannot change size, and therefore it's reasonable to assume * that its null bitmap (if any) doesn't change either. So we just * overwrite the data portion of the tuple without touching the null * bitmap or any of the header fields. * * tuple is an in-memory tuple structure containing the data to be written * over the target tuple. Also, tuple->t_self identifies the target tuple. */ void heap_inplace_update(Relation relation, HeapTuple tuple) { Buffer buffer; Page page; OffsetNumber offnum; ItemId lp = NULL; HeapTupleHeader htup; uint32 oldlen; uint32 newlen; buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&(tuple->t_self))); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); page = (Page) BufferGetPage(buffer); offnum = ItemPointerGetOffsetNumber(&(tuple->t_self)); if (PageGetMaxOffsetNumber(page) >= offnum) lp = PageGetItemId(page, offnum); if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsUsed(lp)) elog(ERROR, "heap_inplace_update: invalid lp"); htup = (HeapTupleHeader) PageGetItem(page, lp); oldlen = ItemIdGetLength(lp) - htup->t_hoff; newlen = tuple->t_len - tuple->t_data->t_hoff; if (oldlen != newlen || htup->t_hoff != tuple->t_data->t_hoff) elog(ERROR, "heap_inplace_update: wrong tuple length"); /* NO EREPORT(ERROR) from here till changes are logged */ START_CRIT_SECTION(); memcpy((char *) htup + htup->t_hoff, (char *) tuple->t_data + tuple->t_data->t_hoff, newlen); MarkBufferDirty(buffer); /* XLOG stuff */ if (!relation->rd_istemp) { xl_heap_inplace xlrec; XLogRecPtr recptr; XLogRecData rdata[2]; xlrec.target.node = relation->rd_node; xlrec.target.tid = tuple->t_self; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapInplace; rdata[0].buffer = InvalidBuffer; rdata[0].next = &(rdata[1]); rdata[1].data = (char *) htup + htup->t_hoff; rdata[1].len = newlen; rdata[1].buffer = buffer; rdata[1].buffer_std = true; rdata[1].next = NULL; recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_INPLACE, rdata); PageSetLSN(page, recptr); PageSetTLI(page, ThisTimeLineID); } END_CRIT_SECTION(); UnlockReleaseBuffer(buffer); /* Send out shared cache inval if necessary */ if (!IsBootstrapProcessingMode()) CacheInvalidateHeapTuple(relation, tuple); } /* * heap_freeze_tuple * * Check to see whether any of the XID fields of a tuple (xmin, xmax, xvac) * are older than the specified cutoff XID. If so, replace them with * FrozenTransactionId or InvalidTransactionId as appropriate, and return * TRUE. Return FALSE if nothing was changed. * * It is assumed that the caller has checked the tuple with * HeapTupleSatisfiesVacuum() and determined that it is not HEAPTUPLE_DEAD * (else we should be removing the tuple, not freezing it). * * NB: cutoff_xid *must* be <= the current global xmin, to ensure that any * XID older than it could neither be running nor seen as running by any * open transaction. This ensures that the replacement will not change * anyone's idea of the tuple state. Also, since we assume the tuple is * not HEAPTUPLE_DEAD, the fact that an XID is not still running allows us * to assume that it is either committed good or aborted, as appropriate; * so we need no external state checks to decide what to do. (This is good * because this function is applied during WAL recovery, when we don't have * access to any such state, and can't depend on the hint bits to be set.) * * In lazy VACUUM, we call this while initially holding only a shared lock * on the tuple's buffer. If any change is needed, we trade that in for an * exclusive lock before making the change. Caller should pass the buffer ID * if shared lock is held, InvalidBuffer if exclusive lock is already held. * * Note: it might seem we could make the changes without exclusive lock, since * TransactionId read/write is assumed atomic anyway. However there is a race * condition: someone who just fetched an old XID that we overwrite here could * conceivably not finish checking the XID against pg_clog before we finish * the VACUUM and perhaps truncate off the part of pg_clog he needs. Getting * exclusive lock ensures no other backend is in process of checking the * tuple status. Also, getting exclusive lock makes it safe to adjust the * infomask bits. */ bool heap_freeze_tuple(HeapTupleHeader tuple, TransactionId cutoff_xid, Buffer buf) { bool changed = false; TransactionId xid; xid = HeapTupleHeaderGetXmin(tuple); if (TransactionIdIsNormal(xid) && TransactionIdPrecedes(xid, cutoff_xid)) { if (buf != InvalidBuffer) { /* trade in share lock for exclusive lock */ LockBuffer(buf, BUFFER_LOCK_UNLOCK); LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE); buf = InvalidBuffer; } HeapTupleHeaderSetXmin(tuple, FrozenTransactionId); /* * Might as well fix the hint bits too; usually XMIN_COMMITTED will * already be set here, but there's a small chance not. */ Assert(!(tuple->t_infomask & HEAP_XMIN_INVALID)); tuple->t_infomask |= HEAP_XMIN_COMMITTED; changed = true; } /* * When we release shared lock, it's possible for someone else to change * xmax before we get the lock back, so repeat the check after acquiring * exclusive lock. (We don't need this pushup for xmin, because only * VACUUM could be interested in changing an existing tuple's xmin, * and there's only one VACUUM allowed on a table at a time.) */ recheck_xmax: if (!(tuple->t_infomask & HEAP_XMAX_IS_MULTI)) { xid = HeapTupleHeaderGetXmax(tuple); if (TransactionIdIsNormal(xid) && TransactionIdPrecedes(xid, cutoff_xid)) { if (buf != InvalidBuffer) { /* trade in share lock for exclusive lock */ LockBuffer(buf, BUFFER_LOCK_UNLOCK); LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE); buf = InvalidBuffer; goto recheck_xmax; /* see comment above */ } HeapTupleHeaderSetXmax(tuple, InvalidTransactionId); /* * The tuple might be marked either XMAX_INVALID or * XMAX_COMMITTED + LOCKED. Normalize to INVALID just to be * sure no one gets confused. */ tuple->t_infomask &= ~HEAP_XMAX_COMMITTED; tuple->t_infomask |= HEAP_XMAX_INVALID; changed = true; } } else { /*---------- * XXX perhaps someday we should zero out very old MultiXactIds here? * * The only way a stale MultiXactId could pose a problem is if a * tuple, having once been multiply-share-locked, is not touched by * any vacuum or attempted lock or deletion for just over 4G MultiXact * creations, and then in the probably-narrow window where its xmax * is again a live MultiXactId, someone tries to lock or delete it. * Even then, another share-lock attempt would work fine. An * exclusive-lock or delete attempt would face unexpected delay, or * in the very worst case get a deadlock error. This seems an * extremely low-probability scenario with minimal downside even if * it does happen, so for now we don't do the extra bookkeeping that * would be needed to clean out MultiXactIds. *---------- */ } /* * Although xvac per se could only be set by VACUUM, it shares physical * storage space with cmax, and so could be wiped out by someone setting * xmax. Hence recheck after changing lock, same as for xmax itself. */ recheck_xvac: if (tuple->t_infomask & HEAP_MOVED) { xid = HeapTupleHeaderGetXvac(tuple); if (TransactionIdIsNormal(xid) && TransactionIdPrecedes(xid, cutoff_xid)) { if (buf != InvalidBuffer) { /* trade in share lock for exclusive lock */ LockBuffer(buf, BUFFER_LOCK_UNLOCK); LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE); buf = InvalidBuffer; goto recheck_xvac; /* see comment above */ } /* * If a MOVED_OFF tuple is not dead, the xvac transaction must * have failed; whereas a non-dead MOVED_IN tuple must mean the * xvac transaction succeeded. */ if (tuple->t_infomask & HEAP_MOVED_OFF) HeapTupleHeaderSetXvac(tuple, InvalidTransactionId); else HeapTupleHeaderSetXvac(tuple, FrozenTransactionId); /* * Might as well fix the hint bits too; usually XMIN_COMMITTED will * already be set here, but there's a small chance not. */ Assert(!(tuple->t_infomask & HEAP_XMIN_INVALID)); tuple->t_infomask |= HEAP_XMIN_COMMITTED; changed = true; } } return changed; } /* ---------------- * heap_markpos - mark scan position * ---------------- */ void heap_markpos(HeapScanDesc scan) { /* Note: no locking manipulations needed */ if (scan->rs_ctup.t_data != NULL) { scan->rs_mctid = scan->rs_ctup.t_self; if (scan->rs_pageatatime) scan->rs_mindex = scan->rs_cindex; } else ItemPointerSetInvalid(&scan->rs_mctid); } /* ---------------- * heap_restrpos - restore position to marked location * ---------------- */ void heap_restrpos(HeapScanDesc scan) { /* XXX no amrestrpos checking that ammarkpos called */ if (!ItemPointerIsValid(&scan->rs_mctid)) { scan->rs_ctup.t_data = NULL; /* * unpin scan buffers */ if (BufferIsValid(scan->rs_cbuf)) ReleaseBuffer(scan->rs_cbuf); scan->rs_cbuf = InvalidBuffer; scan->rs_cblock = InvalidBlockNumber; scan->rs_inited = false; } else { /* * If we reached end of scan, rs_inited will now be false. We must * reset it to true to keep heapgettup from doing the wrong thing. */ scan->rs_inited = true; scan->rs_ctup.t_self = scan->rs_mctid; if (scan->rs_pageatatime) { scan->rs_cindex = scan->rs_mindex; heapgettup_pagemode(scan, NoMovementScanDirection, 0, /* needn't recheck scan keys */ NULL); } else heapgettup(scan, NoMovementScanDirection, 0, /* needn't recheck scan keys */ NULL); } } /* * Perform XLogInsert for a heap-clean operation. Caller must already * have modified the buffer and marked it dirty. * * Note: for historical reasons, the entries in the unused[] array should * be zero-based tuple indexes, not one-based. */ XLogRecPtr log_heap_clean(Relation reln, Buffer buffer, OffsetNumber *unused, int uncnt) { xl_heap_clean xlrec; XLogRecPtr recptr; XLogRecData rdata[2]; /* Caller should not call me on a temp relation */ Assert(!reln->rd_istemp); xlrec.node = reln->rd_node; xlrec.block = BufferGetBlockNumber(buffer); rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapClean; rdata[0].buffer = InvalidBuffer; rdata[0].next = &(rdata[1]); /* * The unused-offsets array is not actually in the buffer, but pretend * that it is. When XLogInsert stores the whole buffer, the offsets array * need not be stored too. */ if (uncnt > 0) { rdata[1].data = (char *) unused; rdata[1].len = uncnt * sizeof(OffsetNumber); } else { rdata[1].data = NULL; rdata[1].len = 0; } rdata[1].buffer = buffer; rdata[1].buffer_std = true; rdata[1].next = NULL; recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_CLEAN, rdata); return recptr; } /* * Perform XLogInsert for a heap-freeze operation. Caller must already * have modified the buffer and marked it dirty. * * Unlike log_heap_clean(), the offsets[] entries are one-based. */ XLogRecPtr log_heap_freeze(Relation reln, Buffer buffer, TransactionId cutoff_xid, OffsetNumber *offsets, int offcnt) { xl_heap_freeze xlrec; XLogRecPtr recptr; XLogRecData rdata[2]; /* Caller should not call me on a temp relation */ Assert(!reln->rd_istemp); xlrec.node = reln->rd_node; xlrec.block = BufferGetBlockNumber(buffer); xlrec.cutoff_xid = cutoff_xid; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapFreeze; rdata[0].buffer = InvalidBuffer; rdata[0].next = &(rdata[1]); /* * The tuple-offsets array is not actually in the buffer, but pretend * that it is. When XLogInsert stores the whole buffer, the offsets array * need not be stored too. */ if (offcnt > 0) { rdata[1].data = (char *) offsets; rdata[1].len = offcnt * sizeof(OffsetNumber); } else { rdata[1].data = NULL; rdata[1].len = 0; } rdata[1].buffer = buffer; rdata[1].buffer_std = true; rdata[1].next = NULL; recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE, rdata); return recptr; } /* * Perform XLogInsert for a heap-update operation. Caller must already * have modified the buffer(s) and marked them dirty. */ static XLogRecPtr log_heap_update(Relation reln, Buffer oldbuf, ItemPointerData from, Buffer newbuf, HeapTuple newtup, bool move) { /* * Note: xlhdr is declared to have adequate size and correct alignment for * an xl_heap_header. However the two tids, if present at all, will be * packed in with no wasted space after the xl_heap_header; they aren't * necessarily aligned as implied by this struct declaration. */ struct { xl_heap_header hdr; TransactionId tid1; TransactionId tid2; } xlhdr; int hsize = SizeOfHeapHeader; xl_heap_update xlrec; XLogRecPtr recptr; XLogRecData rdata[4]; Page page = BufferGetPage(newbuf); uint8 info = (move) ? XLOG_HEAP_MOVE : XLOG_HEAP_UPDATE; /* Caller should not call me on a temp relation */ Assert(!reln->rd_istemp); xlrec.target.node = reln->rd_node; xlrec.target.tid = from; xlrec.newtid = newtup->t_self; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapUpdate; rdata[0].buffer = InvalidBuffer; rdata[0].next = &(rdata[1]); rdata[1].data = NULL; rdata[1].len = 0; rdata[1].buffer = oldbuf; rdata[1].buffer_std = true; rdata[1].next = &(rdata[2]); xlhdr.hdr.t_infomask2 = newtup->t_data->t_infomask2; xlhdr.hdr.t_infomask = newtup->t_data->t_infomask; xlhdr.hdr.t_hoff = newtup->t_data->t_hoff; if (move) /* remember xmax & xmin */ { TransactionId xid[2]; /* xmax, xmin */ if (newtup->t_data->t_infomask & (HEAP_XMAX_INVALID | HEAP_IS_LOCKED)) xid[0] = InvalidTransactionId; else xid[0] = HeapTupleHeaderGetXmax(newtup->t_data); xid[1] = HeapTupleHeaderGetXmin(newtup->t_data); memcpy((char *) &xlhdr + hsize, (char *) xid, 2 * sizeof(TransactionId)); hsize += 2 * sizeof(TransactionId); } /* * As with insert records, we need not store the rdata[2] segment if we * decide to store the whole buffer instead. */ rdata[2].data = (char *) &xlhdr; rdata[2].len = hsize; rdata[2].buffer = newbuf; rdata[2].buffer_std = true; rdata[2].next = &(rdata[3]); /* PG73FORMAT: write bitmap [+ padding] [+ oid] + data */ rdata[3].data = (char *) newtup->t_data + offsetof(HeapTupleHeaderData, t_bits); rdata[3].len = newtup->t_len - offsetof(HeapTupleHeaderData, t_bits); rdata[3].buffer = newbuf; rdata[3].buffer_std = true; rdata[3].next = NULL; /* If new tuple is the single and first tuple on page... */ if (ItemPointerGetOffsetNumber(&(newtup->t_self)) == FirstOffsetNumber && PageGetMaxOffsetNumber(page) == FirstOffsetNumber) { info |= XLOG_HEAP_INIT_PAGE; rdata[2].buffer = rdata[3].buffer = InvalidBuffer; } recptr = XLogInsert(RM_HEAP_ID, info, rdata); return recptr; } /* * Perform XLogInsert for a heap-move operation. Caller must already * have modified the buffers and marked them dirty. */ XLogRecPtr log_heap_move(Relation reln, Buffer oldbuf, ItemPointerData from, Buffer newbuf, HeapTuple newtup) { return log_heap_update(reln, oldbuf, from, newbuf, newtup, true); } /* * Perform XLogInsert of a HEAP_NEWPAGE record to WAL. Caller is responsible * for writing the page to disk after calling this routine. * * Note: all current callers build pages in private memory and write them * directly to smgr, rather than using bufmgr. Therefore there is no need * to pass a buffer ID to XLogInsert, nor to perform MarkBufferDirty within * the critical section. * * Note: the NEWPAGE log record is used for both heaps and indexes, so do * not do anything that assumes we are touching a heap. */ XLogRecPtr log_newpage(RelFileNode *rnode, BlockNumber blkno, Page page) { xl_heap_newpage xlrec; XLogRecPtr recptr; XLogRecData rdata[2]; /* NO ELOG(ERROR) from here till newpage op is logged */ START_CRIT_SECTION(); xlrec.node = *rnode; xlrec.blkno = blkno; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapNewpage; rdata[0].buffer = InvalidBuffer; rdata[0].next = &(rdata[1]); rdata[1].data = (char *) page; rdata[1].len = BLCKSZ; rdata[1].buffer = InvalidBuffer; rdata[1].next = NULL; recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_NEWPAGE, rdata); PageSetLSN(page, recptr); PageSetTLI(page, ThisTimeLineID); END_CRIT_SECTION(); return recptr; } static void heap_xlog_clean(XLogRecPtr lsn, XLogRecord *record) { xl_heap_clean *xlrec = (xl_heap_clean *) XLogRecGetData(record); Relation reln; Buffer buffer; Page page; if (record->xl_info & XLR_BKP_BLOCK_1) return; reln = XLogOpenRelation(xlrec->node); buffer = XLogReadBuffer(reln, xlrec->block, false); if (!BufferIsValid(buffer)) return; page = (Page) BufferGetPage(buffer); if (XLByteLE(lsn, PageGetLSN(page))) { UnlockReleaseBuffer(buffer); return; } if (record->xl_len > SizeOfHeapClean) { OffsetNumber *unused; OffsetNumber *unend; ItemId lp; unused = (OffsetNumber *) ((char *) xlrec + SizeOfHeapClean); unend = (OffsetNumber *) ((char *) xlrec + record->xl_len); while (unused < unend) { /* unused[] entries are zero-based */ lp = PageGetItemId(page, *unused + 1); lp->lp_flags &= ~LP_USED; unused++; } } PageRepairFragmentation(page, NULL); PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); } static void heap_xlog_freeze(XLogRecPtr lsn, XLogRecord *record) { xl_heap_freeze *xlrec = (xl_heap_freeze *) XLogRecGetData(record); TransactionId cutoff_xid = xlrec->cutoff_xid; Relation reln; Buffer buffer; Page page; if (record->xl_info & XLR_BKP_BLOCK_1) return; reln = XLogOpenRelation(xlrec->node); buffer = XLogReadBuffer(reln, xlrec->block, false); if (!BufferIsValid(buffer)) return; page = (Page) BufferGetPage(buffer); if (XLByteLE(lsn, PageGetLSN(page))) { UnlockReleaseBuffer(buffer); return; } if (record->xl_len > SizeOfHeapFreeze) { OffsetNumber *offsets; OffsetNumber *offsets_end; offsets = (OffsetNumber *) ((char *) xlrec + SizeOfHeapFreeze); offsets_end = (OffsetNumber *) ((char *) xlrec + record->xl_len); while (offsets < offsets_end) { /* offsets[] entries are one-based */ ItemId lp = PageGetItemId(page, *offsets); HeapTupleHeader tuple = (HeapTupleHeader) PageGetItem(page, lp); (void) heap_freeze_tuple(tuple, cutoff_xid, InvalidBuffer); offsets++; } } PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); } static void heap_xlog_newpage(XLogRecPtr lsn, XLogRecord *record) { xl_heap_newpage *xlrec = (xl_heap_newpage *) XLogRecGetData(record); Relation reln; Buffer buffer; Page page; /* * Note: the NEWPAGE log record is used for both heaps and indexes, so do * not do anything that assumes we are touching a heap. */ reln = XLogOpenRelation(xlrec->node); buffer = XLogReadBuffer(reln, xlrec->blkno, true); Assert(BufferIsValid(buffer)); page = (Page) BufferGetPage(buffer); Assert(record->xl_len == SizeOfHeapNewpage + BLCKSZ); memcpy(page, (char *) xlrec + SizeOfHeapNewpage, BLCKSZ); PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); } static void heap_xlog_delete(XLogRecPtr lsn, XLogRecord *record) { xl_heap_delete *xlrec = (xl_heap_delete *) XLogRecGetData(record); Relation reln; Buffer buffer; Page page; OffsetNumber offnum; ItemId lp = NULL; HeapTupleHeader htup; if (record->xl_info & XLR_BKP_BLOCK_1) return; reln = XLogOpenRelation(xlrec->target.node); buffer = XLogReadBuffer(reln, ItemPointerGetBlockNumber(&(xlrec->target.tid)), false); if (!BufferIsValid(buffer)) return; page = (Page) BufferGetPage(buffer); if (XLByteLE(lsn, PageGetLSN(page))) /* changes are applied */ { UnlockReleaseBuffer(buffer); return; } offnum = ItemPointerGetOffsetNumber(&(xlrec->target.tid)); if (PageGetMaxOffsetNumber(page) >= offnum) lp = PageGetItemId(page, offnum); if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsUsed(lp)) elog(PANIC, "heap_delete_redo: invalid lp"); htup = (HeapTupleHeader) PageGetItem(page, lp); htup->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | HEAP_XMAX_IS_MULTI | HEAP_IS_LOCKED | HEAP_MOVED); HeapTupleHeaderSetXmax(htup, record->xl_xid); HeapTupleHeaderSetCmax(htup, FirstCommandId, false); /* Make sure there is no forward chain link in t_ctid */ htup->t_ctid = xlrec->target.tid; PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); } static void heap_xlog_insert(XLogRecPtr lsn, XLogRecord *record) { xl_heap_insert *xlrec = (xl_heap_insert *) XLogRecGetData(record); Relation reln; Buffer buffer; Page page; OffsetNumber offnum; struct { HeapTupleHeaderData hdr; char data[MaxHeapTupleSize]; } tbuf; HeapTupleHeader htup; xl_heap_header xlhdr; uint32 newlen; if (record->xl_info & XLR_BKP_BLOCK_1) return; reln = XLogOpenRelation(xlrec->target.node); if (record->xl_info & XLOG_HEAP_INIT_PAGE) { buffer = XLogReadBuffer(reln, ItemPointerGetBlockNumber(&(xlrec->target.tid)), true); Assert(BufferIsValid(buffer)); page = (Page) BufferGetPage(buffer); PageInit(page, BufferGetPageSize(buffer), 0); } else { buffer = XLogReadBuffer(reln, ItemPointerGetBlockNumber(&(xlrec->target.tid)), false); if (!BufferIsValid(buffer)) return; page = (Page) BufferGetPage(buffer); if (XLByteLE(lsn, PageGetLSN(page))) /* changes are applied */ { UnlockReleaseBuffer(buffer); return; } } offnum = ItemPointerGetOffsetNumber(&(xlrec->target.tid)); if (PageGetMaxOffsetNumber(page) + 1 < offnum) elog(PANIC, "heap_insert_redo: invalid max offset number"); newlen = record->xl_len - SizeOfHeapInsert - SizeOfHeapHeader; Assert(newlen <= MaxHeapTupleSize); memcpy((char *) &xlhdr, (char *) xlrec + SizeOfHeapInsert, SizeOfHeapHeader); htup = &tbuf.hdr; MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData)); /* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */ memcpy((char *) htup + offsetof(HeapTupleHeaderData, t_bits), (char *) xlrec + SizeOfHeapInsert + SizeOfHeapHeader, newlen); newlen += offsetof(HeapTupleHeaderData, t_bits); htup->t_infomask2 = xlhdr.t_infomask2; htup->t_infomask = xlhdr.t_infomask; htup->t_hoff = xlhdr.t_hoff; HeapTupleHeaderSetXmin(htup, record->xl_xid); HeapTupleHeaderSetCmin(htup, FirstCommandId); htup->t_ctid = xlrec->target.tid; offnum = PageAddItem(page, (Item) htup, newlen, offnum, LP_USED | OverwritePageMode); if (offnum == InvalidOffsetNumber) elog(PANIC, "heap_insert_redo: failed to add tuple"); PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); } /* * Handles UPDATE & MOVE */ static void heap_xlog_update(XLogRecPtr lsn, XLogRecord *record, bool move) { xl_heap_update *xlrec = (xl_heap_update *) XLogRecGetData(record); Relation reln = XLogOpenRelation(xlrec->target.node); Buffer buffer; bool samepage = (ItemPointerGetBlockNumber(&(xlrec->newtid)) == ItemPointerGetBlockNumber(&(xlrec->target.tid))); Page page; OffsetNumber offnum; ItemId lp = NULL; HeapTupleHeader htup; struct { HeapTupleHeaderData hdr; char data[MaxHeapTupleSize]; } tbuf; xl_heap_header xlhdr; int hsize; uint32 newlen; if (record->xl_info & XLR_BKP_BLOCK_1) { if (samepage) return; /* backup block covered both changes */ goto newt; } /* Deal with old tuple version */ buffer = XLogReadBuffer(reln, ItemPointerGetBlockNumber(&(xlrec->target.tid)), false); if (!BufferIsValid(buffer)) goto newt; page = (Page) BufferGetPage(buffer); if (XLByteLE(lsn, PageGetLSN(page))) /* changes are applied */ { UnlockReleaseBuffer(buffer); if (samepage) return; goto newt; } offnum = ItemPointerGetOffsetNumber(&(xlrec->target.tid)); if (PageGetMaxOffsetNumber(page) >= offnum) lp = PageGetItemId(page, offnum); if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsUsed(lp)) elog(PANIC, "heap_update_redo: invalid lp"); htup = (HeapTupleHeader) PageGetItem(page, lp); if (move) { htup->t_infomask &= ~(HEAP_XMIN_COMMITTED | HEAP_XMIN_INVALID | HEAP_MOVED_IN); htup->t_infomask |= HEAP_MOVED_OFF; HeapTupleHeaderSetXvac(htup, record->xl_xid); /* Make sure there is no forward chain link in t_ctid */ htup->t_ctid = xlrec->target.tid; } else { htup->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | HEAP_XMAX_IS_MULTI | HEAP_IS_LOCKED | HEAP_MOVED); HeapTupleHeaderSetXmax(htup, record->xl_xid); HeapTupleHeaderSetCmax(htup, FirstCommandId, false); /* Set forward chain link in t_ctid */ htup->t_ctid = xlrec->newtid; } /* * this test is ugly, but necessary to avoid thinking that insert change * is already applied */ if (samepage) goto newsame; PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); /* Deal with new tuple */ newt:; if (record->xl_info & XLR_BKP_BLOCK_2) return; if (record->xl_info & XLOG_HEAP_INIT_PAGE) { buffer = XLogReadBuffer(reln, ItemPointerGetBlockNumber(&(xlrec->newtid)), true); Assert(BufferIsValid(buffer)); page = (Page) BufferGetPage(buffer); PageInit(page, BufferGetPageSize(buffer), 0); } else { buffer = XLogReadBuffer(reln, ItemPointerGetBlockNumber(&(xlrec->newtid)), false); if (!BufferIsValid(buffer)) return; page = (Page) BufferGetPage(buffer); if (XLByteLE(lsn, PageGetLSN(page))) /* changes are applied */ { UnlockReleaseBuffer(buffer); return; } } newsame:; offnum = ItemPointerGetOffsetNumber(&(xlrec->newtid)); if (PageGetMaxOffsetNumber(page) + 1 < offnum) elog(PANIC, "heap_update_redo: invalid max offset number"); hsize = SizeOfHeapUpdate + SizeOfHeapHeader; if (move) hsize += (2 * sizeof(TransactionId)); newlen = record->xl_len - hsize; Assert(newlen <= MaxHeapTupleSize); memcpy((char *) &xlhdr, (char *) xlrec + SizeOfHeapUpdate, SizeOfHeapHeader); htup = &tbuf.hdr; MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData)); /* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */ memcpy((char *) htup + offsetof(HeapTupleHeaderData, t_bits), (char *) xlrec + hsize, newlen); newlen += offsetof(HeapTupleHeaderData, t_bits); htup->t_infomask2 = xlhdr.t_infomask2; htup->t_infomask = xlhdr.t_infomask; htup->t_hoff = xlhdr.t_hoff; if (move) { TransactionId xid[2]; /* xmax, xmin */ memcpy((char *) xid, (char *) xlrec + SizeOfHeapUpdate + SizeOfHeapHeader, 2 * sizeof(TransactionId)); HeapTupleHeaderSetXmin(htup, xid[1]); HeapTupleHeaderSetXmax(htup, xid[0]); HeapTupleHeaderSetXvac(htup, record->xl_xid); } else { HeapTupleHeaderSetXmin(htup, record->xl_xid); HeapTupleHeaderSetCmin(htup, FirstCommandId); } /* Make sure there is no forward chain link in t_ctid */ htup->t_ctid = xlrec->newtid; offnum = PageAddItem(page, (Item) htup, newlen, offnum, LP_USED | OverwritePageMode); if (offnum == InvalidOffsetNumber) elog(PANIC, "heap_update_redo: failed to add tuple"); PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); } static void heap_xlog_lock(XLogRecPtr lsn, XLogRecord *record) { xl_heap_lock *xlrec = (xl_heap_lock *) XLogRecGetData(record); Relation reln; Buffer buffer; Page page; OffsetNumber offnum; ItemId lp = NULL; HeapTupleHeader htup; if (record->xl_info & XLR_BKP_BLOCK_1) return; reln = XLogOpenRelation(xlrec->target.node); buffer = XLogReadBuffer(reln, ItemPointerGetBlockNumber(&(xlrec->target.tid)), false); if (!BufferIsValid(buffer)) return; page = (Page) BufferGetPage(buffer); if (XLByteLE(lsn, PageGetLSN(page))) /* changes are applied */ { UnlockReleaseBuffer(buffer); return; } offnum = ItemPointerGetOffsetNumber(&(xlrec->target.tid)); if (PageGetMaxOffsetNumber(page) >= offnum) lp = PageGetItemId(page, offnum); if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsUsed(lp)) elog(PANIC, "heap_lock_redo: invalid lp"); htup = (HeapTupleHeader) PageGetItem(page, lp); htup->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | HEAP_XMAX_IS_MULTI | HEAP_IS_LOCKED | HEAP_MOVED); if (xlrec->xid_is_mxact) htup->t_infomask |= HEAP_XMAX_IS_MULTI; if (xlrec->shared_lock) htup->t_infomask |= HEAP_XMAX_SHARED_LOCK; else htup->t_infomask |= HEAP_XMAX_EXCL_LOCK; HeapTupleHeaderSetXmax(htup, xlrec->locking_xid); HeapTupleHeaderSetCmax(htup, FirstCommandId, false); /* Make sure there is no forward chain link in t_ctid */ htup->t_ctid = xlrec->target.tid; PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); } static void heap_xlog_inplace(XLogRecPtr lsn, XLogRecord *record) { xl_heap_inplace *xlrec = (xl_heap_inplace *) XLogRecGetData(record); Relation reln = XLogOpenRelation(xlrec->target.node); Buffer buffer; Page page; OffsetNumber offnum; ItemId lp = NULL; HeapTupleHeader htup; uint32 oldlen; uint32 newlen; if (record->xl_info & XLR_BKP_BLOCK_1) return; buffer = XLogReadBuffer(reln, ItemPointerGetBlockNumber(&(xlrec->target.tid)), false); if (!BufferIsValid(buffer)) return; page = (Page) BufferGetPage(buffer); if (XLByteLE(lsn, PageGetLSN(page))) /* changes are applied */ { UnlockReleaseBuffer(buffer); return; } offnum = ItemPointerGetOffsetNumber(&(xlrec->target.tid)); if (PageGetMaxOffsetNumber(page) >= offnum) lp = PageGetItemId(page, offnum); if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsUsed(lp)) elog(PANIC, "heap_inplace_redo: invalid lp"); htup = (HeapTupleHeader) PageGetItem(page, lp); oldlen = ItemIdGetLength(lp) - htup->t_hoff; newlen = record->xl_len - SizeOfHeapInplace; if (oldlen != newlen) elog(PANIC, "heap_inplace_redo: wrong tuple length"); memcpy((char *) htup + htup->t_hoff, (char *) xlrec + SizeOfHeapInplace, newlen); PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); } void heap_redo(XLogRecPtr lsn, XLogRecord *record) { uint8 info = record->xl_info & ~XLR_INFO_MASK; info &= XLOG_HEAP_OPMASK; if (info == XLOG_HEAP_INSERT) heap_xlog_insert(lsn, record); else if (info == XLOG_HEAP_DELETE) heap_xlog_delete(lsn, record); else if (info == XLOG_HEAP_UPDATE) heap_xlog_update(lsn, record, false); else if (info == XLOG_HEAP_MOVE) heap_xlog_update(lsn, record, true); else if (info == XLOG_HEAP_CLEAN) heap_xlog_clean(lsn, record); else if (info == XLOG_HEAP_NEWPAGE) heap_xlog_newpage(lsn, record); else if (info == XLOG_HEAP_LOCK) heap_xlog_lock(lsn, record); else if (info == XLOG_HEAP_INPLACE) heap_xlog_inplace(lsn, record); else elog(PANIC, "heap_redo: unknown op code %u", info); } void heap2_redo(XLogRecPtr lsn, XLogRecord *record) { uint8 info = record->xl_info & ~XLR_INFO_MASK; info &= XLOG_HEAP_OPMASK; if (info == XLOG_HEAP2_FREEZE) heap_xlog_freeze(lsn, record); else elog(PANIC, "heap2_redo: unknown op code %u", info); } static void out_target(StringInfo buf, xl_heaptid *target) { appendStringInfo(buf, "rel %u/%u/%u; tid %u/%u", target->node.spcNode, target->node.dbNode, target->node.relNode, ItemPointerGetBlockNumber(&(target->tid)), ItemPointerGetOffsetNumber(&(target->tid))); } void heap_desc(StringInfo buf, uint8 xl_info, char *rec) { uint8 info = xl_info & ~XLR_INFO_MASK; info &= XLOG_HEAP_OPMASK; if (info == XLOG_HEAP_INSERT) { xl_heap_insert *xlrec = (xl_heap_insert *) rec; if (xl_info & XLOG_HEAP_INIT_PAGE) appendStringInfo(buf, "insert(init): "); else appendStringInfo(buf, "insert: "); out_target(buf, &(xlrec->target)); } else if (info == XLOG_HEAP_DELETE) { xl_heap_delete *xlrec = (xl_heap_delete *) rec; appendStringInfo(buf, "delete: "); out_target(buf, &(xlrec->target)); } else if (info == XLOG_HEAP_UPDATE) { xl_heap_update *xlrec = (xl_heap_update *) rec; if (xl_info & XLOG_HEAP_INIT_PAGE) appendStringInfo(buf, "update(init): "); else appendStringInfo(buf, "update: "); out_target(buf, &(xlrec->target)); appendStringInfo(buf, "; new %u/%u", ItemPointerGetBlockNumber(&(xlrec->newtid)), ItemPointerGetOffsetNumber(&(xlrec->newtid))); } else if (info == XLOG_HEAP_MOVE) { xl_heap_update *xlrec = (xl_heap_update *) rec; if (xl_info & XLOG_HEAP_INIT_PAGE) appendStringInfo(buf, "move(init): "); else appendStringInfo(buf, "move: "); out_target(buf, &(xlrec->target)); appendStringInfo(buf, "; new %u/%u", ItemPointerGetBlockNumber(&(xlrec->newtid)), ItemPointerGetOffsetNumber(&(xlrec->newtid))); } else if (info == XLOG_HEAP_CLEAN) { xl_heap_clean *xlrec = (xl_heap_clean *) rec; appendStringInfo(buf, "clean: rel %u/%u/%u; blk %u", xlrec->node.spcNode, xlrec->node.dbNode, xlrec->node.relNode, xlrec->block); } else if (info == XLOG_HEAP_NEWPAGE) { xl_heap_newpage *xlrec = (xl_heap_newpage *) rec; appendStringInfo(buf, "newpage: rel %u/%u/%u; blk %u", xlrec->node.spcNode, xlrec->node.dbNode, xlrec->node.relNode, xlrec->blkno); } else if (info == XLOG_HEAP_LOCK) { xl_heap_lock *xlrec = (xl_heap_lock *) rec; if (xlrec->shared_lock) appendStringInfo(buf, "shared_lock: "); else appendStringInfo(buf, "exclusive_lock: "); if (xlrec->xid_is_mxact) appendStringInfo(buf, "mxid "); else appendStringInfo(buf, "xid "); appendStringInfo(buf, "%u ", xlrec->locking_xid); out_target(buf, &(xlrec->target)); } else if (info == XLOG_HEAP_INPLACE) { xl_heap_inplace *xlrec = (xl_heap_inplace *) rec; appendStringInfo(buf, "inplace: "); out_target(buf, &(xlrec->target)); } else appendStringInfo(buf, "UNKNOWN"); } void heap2_desc(StringInfo buf, uint8 xl_info, char *rec) { uint8 info = xl_info & ~XLR_INFO_MASK; info &= XLOG_HEAP_OPMASK; if (info == XLOG_HEAP2_FREEZE) { xl_heap_freeze *xlrec = (xl_heap_freeze *) rec; appendStringInfo(buf, "freeze: rel %u/%u/%u; blk %u; cutoff %u", xlrec->node.spcNode, xlrec->node.dbNode, xlrec->node.relNode, xlrec->block, xlrec->cutoff_xid); } else appendStringInfo(buf, "UNKNOWN"); } /* * heap_sync - sync a heap, for use when no WAL has been written * * This forces the heap contents (including TOAST heap if any) down to disk. * If we skipped using WAL, and it's not a temp relation, we must force the * relation down to disk before it's safe to commit the transaction. This * requires writing out any dirty buffers and then doing a forced fsync. * * Indexes are not touched. (Currently, index operations associated with * the commands that use this are WAL-logged and so do not need fsync. * That behavior might change someday, but in any case it's likely that * any fsync decisions required would be per-index and hence not appropriate * to be done here.) */ void heap_sync(Relation rel) { /* temp tables never need fsync */ if (rel->rd_istemp) return; /* main heap */ FlushRelationBuffers(rel); /* FlushRelationBuffers will have opened rd_smgr */ smgrimmedsync(rel->rd_smgr); /* toast heap, if any */ if (OidIsValid(rel->rd_rel->reltoastrelid)) { Relation toastrel; toastrel = heap_open(rel->rd_rel->reltoastrelid, AccessShareLock); FlushRelationBuffers(toastrel); smgrimmedsync(toastrel->rd_smgr); heap_close(toastrel, AccessShareLock); } }