/*------------------------------------------------------------------------- * * heapam.c * heap access method code * * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * src/backend/access/heap/heapam.c * * * 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/relscan.h" #include "access/sysattr.h" #include "access/transam.h" #include "access/tuptoaster.h" #include "access/valid.h" #include "access/visibilitymap.h" #include "access/xact.h" #include "access/xlogutils.h" #include "catalog/catalog.h" #include "catalog/namespace.h" #include "miscadmin.h" #include "pgstat.h" #include "storage/bufmgr.h" #include "storage/freespace.h" #include "storage/lmgr.h" #include "storage/predicate.h" #include "storage/procarray.h" #include "storage/smgr.h" #include "storage/standby.h" #include "utils/datum.h" #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/relcache.h" #include "utils/snapmgr.h" #include "utils/syscache.h" #include "utils/tqual.h" /* GUC variable */ bool synchronize_seqscans = true; static HeapScanDesc heap_beginscan_internal(Relation relation, Snapshot snapshot, int nkeys, ScanKey key, bool allow_strat, bool allow_sync, bool is_bitmapscan); static XLogRecPtr log_heap_update(Relation reln, Buffer oldbuf, ItemPointerData from, Buffer newbuf, HeapTuple newtup, bool all_visible_cleared, bool new_all_visible_cleared); static bool HeapSatisfiesHOTUpdate(Relation relation, Bitmapset *hot_attrs, HeapTuple oldtup, HeapTuple newtup); /* ---------------------------------------------------------------- * heap support routines * ---------------------------------------------------------------- */ /* ---------------- * initscan - scan code common to heap_beginscan and heap_rescan * ---------------- */ static void initscan(HeapScanDesc scan, ScanKey key, bool is_rescan) { bool allow_strat; bool allow_sync; /* * 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. * (However, some callers need to be able to disable one or both of these * behaviors, independently of the size of the table; also there is a GUC * variable that can disable synchronized scanning.) * * During a rescan, don't make a new strategy object if we don't have to. */ if (!RelationUsesLocalBuffers(scan->rs_rd) && scan->rs_nblocks > NBuffers / 4) { allow_strat = scan->rs_allow_strat; allow_sync = scan->rs_allow_sync; } else allow_strat = allow_sync = false; if (allow_strat) { if (scan->rs_strategy == NULL) scan->rs_strategy = GetAccessStrategy(BAS_BULKREAD); } else { if (scan->rs_strategy != NULL) FreeAccessStrategy(scan->rs_strategy); scan->rs_strategy = NULL; } if (is_rescan) { /* * If rescan, keep the previous startblock setting so that rewinding a * cursor doesn't generate surprising results. Reset the syncscan * setting, though. */ scan->rs_syncscan = (allow_sync && synchronize_seqscans); } else if (allow_sync && synchronize_seqscans) { scan->rs_syncscan = true; scan->rs_startblock = ss_get_location(scan->rs_rd, scan->rs_nblocks); } else { 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; bool all_visible; 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 = ReadBufferExtended(scan->rs_rd, MAIN_FORKNUM, page, RBM_NORMAL, scan->rs_strategy); scan->rs_cblock = page; if (!scan->rs_pageatatime) return; buffer = scan->rs_cbuf; snapshot = scan->rs_snapshot; /* * Prune and repair fragmentation for the whole page, if possible. */ Assert(TransactionIdIsValid(RecentGlobalXmin)); heap_page_prune_opt(scan->rs_rd, buffer, RecentGlobalXmin); /* * 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; /* * If the all-visible flag indicates that all tuples on the page are * visible to everyone, we can skip the per-tuple visibility tests. But * not in hot standby mode. A tuple that's already visible to all * transactions in the master might still be invisible to a read-only * transaction in the standby. */ all_visible = PageIsAllVisible(dp) && !snapshot->takenDuringRecovery; for (lineoff = FirstOffsetNumber, lpp = PageGetItemId(dp, lineoff); lineoff <= lines; lineoff++, lpp++) { if (ItemIdIsNormal(lpp)) { HeapTupleData loctup; bool valid; loctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp); loctup.t_len = ItemIdGetLength(lpp); ItemPointerSet(&(loctup.t_self), page, lineoff); if (all_visible) valid = true; else valid = HeapTupleSatisfiesVisibility(&loctup, snapshot, buffer); CheckForSerializableConflictOut(valid, scan->rs_rd, &loctup, buffer, snapshot); 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); Assert(ItemIdIsNormal(lpp)); 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 (ItemIdIsNormal(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); CheckForSerializableConflictOut(valid, scan->rs_rd, tuple, scan->rs_cbuf, snapshot); if (valid && key != NULL) HeapKeyTest(tuple, RelationGetDescr(scan->rs_rd), nkeys, key, valid); if (valid) { if (!scan->rs_relpredicatelocked) PredicateLockTuple(scan->rs_rd, tuple, snapshot); 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); Assert(ItemIdIsNormal(lpp)); 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(ItemIdIsNormal(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) { if (!scan->rs_relpredicatelocked) PredicateLockTuple(scan->rs_rd, tuple, scan->rs_snapshot); scan->rs_cindex = lineindex; return; } } else { if (!scan->rs_relpredicatelocked) PredicateLockTuple(scan->rs_rd, tuple, scan->rs_snapshot); 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) = false), 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)) ) : ( att_isnull((attnum) - 1, (tup)->t_data->t_bits) ? ( (*(isnull) = true), (Datum) NULL ) : ( nocachegetattr((tup), (attnum), (tupleDesc)) ) ) ) : ( (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); /* Make note that we've accessed a temporary relation */ if (RelationUsesLocalBuffers(r)) MyXactAccessedTempRel = true; 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 (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(relationId))) { /* 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); /* Make note that we've accessed a temporary relation */ if (RelationUsesLocalBuffers(r)) MyXactAccessedTempRel = true; 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); } /* ---------------- * try_relation_openrv - open any relation specified by a RangeVar * * Same as relation_openrv, but return NULL instead of failing for * relation-not-found. (Note that some other causes, such as * permissions problems, will still result in an ereport.) * ---------------- */ Relation try_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, true); /* Return NULL on not-found */ if (!OidIsValid(relOid)) return NULL; /* 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 or foreign table 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; } /* ---------------- * try_heap_openrv - open a heap relation specified * by a RangeVar node * * As above, but return NULL instead of failing for relation-not-found. * ---------------- */ Relation try_heap_openrv(const RangeVar *relation, LOCKMODE lockmode) { Relation r; r = try_relation_openrv(relation, lockmode); if (r) { 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_strat offers an extended API that lets the caller control * whether a nondefault buffer access strategy can be used, and whether * syncscan can be chosen (possibly resulting in the scan not starting from * block zero). Both of these default to TRUE with plain heap_beginscan. * * heap_beginscan_bm is an alternative 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, true, true, false); } HeapScanDesc heap_beginscan_strat(Relation relation, Snapshot snapshot, int nkeys, ScanKey key, bool allow_strat, bool allow_sync) { return heap_beginscan_internal(relation, snapshot, nkeys, key, allow_strat, allow_sync, false); } HeapScanDesc heap_beginscan_bm(Relation relation, Snapshot snapshot, int nkeys, ScanKey key) { return heap_beginscan_internal(relation, snapshot, nkeys, key, false, false, true); } static HeapScanDesc heap_beginscan_internal(Relation relation, Snapshot snapshot, int nkeys, ScanKey key, bool allow_strat, bool allow_sync, 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 */ scan->rs_allow_strat = allow_strat; scan->rs_allow_sync = allow_sync; scan->rs_relpredicatelocked = false; /* * 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, false); 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, true); } /* ---------------- * 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.) * * heap_fetch does not follow HOT chains: only the exact TID requested will * be fetched. * * 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) { ItemPointer tid = &(tuple->t_self); ItemId lp; Buffer buffer; Page page; OffsetNumber offnum; bool valid; /* * Fetch and pin the appropriate page of the relation. */ buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid)); /* * Need share lock on buffer to examine tuple commit status. */ LockBuffer(buffer, BUFFER_LOCK_SHARE); page = 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(page)) { 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(page, offnum); /* * Must check for deleted tuple. */ if (!ItemIdIsNormal(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, lp); tuple->t_len = ItemIdGetLength(lp); tuple->t_tableOid = RelationGetRelid(relation); /* * check time qualification of tuple, then release lock */ valid = HeapTupleSatisfiesVisibility(tuple, snapshot, buffer); if (valid) PredicateLockTuple(relation, tuple, snapshot); CheckForSerializableConflictOut(valid, relation, tuple, buffer, snapshot); 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_hot_search_buffer - search HOT chain for tuple satisfying snapshot * * On entry, *tid is the TID of a tuple (either a simple tuple, or the root * of a HOT chain), and buffer is the buffer holding this tuple. We search * for the first chain member satisfying the given snapshot. If one is * found, we update *tid to reference that tuple's offset number, and * return TRUE. If no match, return FALSE without modifying *tid. * * heapTuple is a caller-supplied buffer. When a match is found, we return * the tuple here, in addition to updating *tid. If no match is found, the * contents of this buffer on return are undefined. * * If all_dead is not NULL, we check non-visible tuples to see if they are * globally dead; *all_dead is set TRUE if all members of the HOT chain * are vacuumable, FALSE if not. * * Unlike heap_fetch, the caller must already have pin and (at least) share * lock on the buffer; it is still pinned/locked at exit. Also unlike * heap_fetch, we do not report any pgstats count; caller may do so if wanted. */ bool heap_hot_search_buffer(ItemPointer tid, Relation relation, Buffer buffer, Snapshot snapshot, HeapTuple heapTuple, bool *all_dead, bool first_call) { Page dp = (Page) BufferGetPage(buffer); TransactionId prev_xmax = InvalidTransactionId; OffsetNumber offnum; bool at_chain_start; bool valid; bool skip; /* If this is not the first call, previous call returned a (live!) tuple */ if (all_dead) *all_dead = first_call; Assert(TransactionIdIsValid(RecentGlobalXmin)); Assert(ItemPointerGetBlockNumber(tid) == BufferGetBlockNumber(buffer)); offnum = ItemPointerGetOffsetNumber(tid); at_chain_start = first_call; skip = !first_call; /* Scan through possible multiple members of HOT-chain */ for (;;) { ItemId lp; /* check for bogus TID */ if (offnum < FirstOffsetNumber || offnum > PageGetMaxOffsetNumber(dp)) break; lp = PageGetItemId(dp, offnum); /* check for unused, dead, or redirected items */ if (!ItemIdIsNormal(lp)) { /* We should only see a redirect at start of chain */ if (ItemIdIsRedirected(lp) && at_chain_start) { /* Follow the redirect */ offnum = ItemIdGetRedirect(lp); at_chain_start = false; continue; } /* else must be end of chain */ break; } heapTuple->t_data = (HeapTupleHeader) PageGetItem(dp, lp); heapTuple->t_len = ItemIdGetLength(lp); heapTuple->t_tableOid = relation->rd_id; heapTuple->t_self = *tid; /* * Shouldn't see a HEAP_ONLY tuple at chain start. */ if (at_chain_start && HeapTupleIsHeapOnly(heapTuple)) break; /* * The xmin should match the previous xmax value, else chain is * broken. */ if (TransactionIdIsValid(prev_xmax) && !TransactionIdEquals(prev_xmax, HeapTupleHeaderGetXmin(heapTuple->t_data))) break; /* * When first_call is true (and thus, skip is initally false) we'll * return the first tuple we find. But on later passes, heapTuple * will initially be pointing to the tuple we returned last time. * Returning it again would be incorrect (and would loop forever), * so we skip it and return the next match we find. */ if (!skip) { /* If it's visible per the snapshot, we must return it */ valid = HeapTupleSatisfiesVisibility(heapTuple, snapshot, buffer); CheckForSerializableConflictOut(valid, relation, heapTuple, buffer, snapshot); if (valid) { ItemPointerSetOffsetNumber(tid, offnum); PredicateLockTuple(relation, heapTuple, snapshot); if (all_dead) *all_dead = false; return true; } } skip = false; /* * If we can't see it, maybe no one else can either. At caller * request, check whether all chain members are dead to all * transactions. */ if (all_dead && *all_dead && HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin, buffer) != HEAPTUPLE_DEAD) *all_dead = false; /* * Check to see if HOT chain continues past this tuple; if so fetch * the next offnum and loop around. */ if (HeapTupleIsHotUpdated(heapTuple)) { Assert(ItemPointerGetBlockNumber(&heapTuple->t_data->t_ctid) == ItemPointerGetBlockNumber(tid)); offnum = ItemPointerGetOffsetNumber(&heapTuple->t_data->t_ctid); at_chain_start = false; prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data); } else break; /* end of chain */ } return false; } /* * heap_hot_search - search HOT chain for tuple satisfying snapshot * * This has the same API as heap_hot_search_buffer, except that the caller * does not provide the buffer containing the page, rather we access it * locally. */ bool heap_hot_search(ItemPointer tid, Relation relation, Snapshot snapshot, bool *all_dead) { bool result; Buffer buffer; HeapTupleData heapTuple; buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid)); LockBuffer(buffer, BUFFER_LOCK_SHARE); result = heap_hot_search_buffer(tid, relation, buffer, snapshot, &heapTuple, all_dead, true); LockBuffer(buffer, BUFFER_LOCK_UNLOCK); ReleaseBuffer(buffer); return result; } /* * 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; Page page; OffsetNumber offnum; ItemId lp; HeapTupleData tp; bool valid; /* * Read, pin, and lock the page. */ buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&ctid)); LockBuffer(buffer, BUFFER_LOCK_SHARE); page = 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(page)) { UnlockReleaseBuffer(buffer); break; } lp = PageGetItemId(page, offnum); if (!ItemIdIsNormal(lp)) { UnlockReleaseBuffer(buffer); break; } /* OK to access the tuple */ tp.t_self = ctid; tp.t_data = (HeapTupleHeader) PageGetItem(page, 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); CheckForSerializableConflictOut(valid, relation, &tp, buffer, snapshot); 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); } } /* * GetBulkInsertState - prepare status object for a bulk insert */ BulkInsertState GetBulkInsertState(void) { BulkInsertState bistate; bistate = (BulkInsertState) palloc(sizeof(BulkInsertStateData)); bistate->strategy = GetAccessStrategy(BAS_BULKWRITE); bistate->current_buf = InvalidBuffer; return bistate; } /* * FreeBulkInsertState - clean up after finishing a bulk insert */ void FreeBulkInsertState(BulkInsertState bistate) { if (bistate->current_buf != InvalidBuffer) ReleaseBuffer(bistate->current_buf); FreeAccessStrategy(bistate->strategy); pfree(bistate); } /* * heap_insert - insert tuple into a heap * * The new tuple is stamped with current transaction ID and the specified * command ID. * * If the HEAP_INSERT_SKIP_WAL option is specified, 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) * * The HEAP_INSERT_SKIP_FSM option is passed directly to * RelationGetBufferForTuple, which see for more info. * * Note that these options will be applied when inserting into the heap's * TOAST table, too, if the tuple requires any out-of-line data. * * The BulkInsertState object (if any; bistate can be NULL for default * behavior) is also just passed through to RelationGetBufferForTuple. * * 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, int options, BulkInsertState bistate) { TransactionId xid = GetCurrentTransactionId(); HeapTuple heaptup; Buffer buffer; Buffer vmbuffer = InvalidBuffer; bool all_visible_cleared = false; 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_infomask2 &= ~(HEAP2_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_RELATION) { /* 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, options); else heaptup = tup; /* * Find buffer to insert this tuple into. If the page is all visible, * this will also pin the requisite visibility map page. */ buffer = RelationGetBufferForTuple(relation, heaptup->t_len, InvalidBuffer, options, bistate, &vmbuffer); /* * We're about to do the actual insert -- check for conflict at the * relation or buffer level first, to avoid possibly having to roll back * work we've just done. */ CheckForSerializableConflictIn(relation, NULL, buffer); /* NO EREPORT(ERROR) from here till changes are logged */ START_CRIT_SECTION(); RelationPutHeapTuple(relation, buffer, heaptup); if (PageIsAllVisible(BufferGetPage(buffer))) { all_visible_cleared = true; PageClearAllVisible(BufferGetPage(buffer)); visibilitymap_clear(relation, ItemPointerGetBlockNumber(&(heaptup->t_self)), vmbuffer); } /* * XXX Should we set PageSetPrunable on this page ? * * The inserting transaction may eventually abort thus making this tuple * DEAD and hence available for pruning. Though we don't want to optimize * for aborts, if no other tuple in this page is UPDATEd/DELETEd, the * aborted tuple will never be pruned until next vacuum is triggered. * * If you do add PageSetPrunable here, add it in heap_xlog_insert too. */ MarkBufferDirty(buffer); /* XLOG stuff */ if (!(options & HEAP_INSERT_SKIP_WAL) && RelationNeedsWAL(relation)) { xl_heap_insert xlrec; xl_heap_header xlhdr; XLogRecPtr recptr; XLogRecData rdata[3]; Page page = BufferGetPage(buffer); uint8 info = XLOG_HEAP_INSERT; xlrec.all_visible_cleared = all_visible_cleared; 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 (vmbuffer != InvalidBuffer) ReleaseBuffer(vmbuffer); /* * 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), 0, NULL); } /* * 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; Page page; BlockNumber block; Buffer buffer; Buffer vmbuffer = InvalidBuffer; bool have_tuple_lock = false; bool iscombo; bool all_visible_cleared = false; Assert(ItemPointerIsValid(tid)); block = ItemPointerGetBlockNumber(tid); buffer = ReadBuffer(relation, block); page = BufferGetPage(buffer); /* * Before locking the buffer, pin the visibility map page if it appears * to be necessary. Since we haven't got the lock yet, someone else might * be in the middle of changing this, so we'll need to recheck after * we have the lock. */ if (PageIsAllVisible(page)) visibilitymap_pin(relation, block, &vmbuffer); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); /* * If we didn't pin the visibility map page and the page has become all * visible while we were busy locking the buffer, we'll have to unlock and * re-lock, to avoid holding the buffer lock across an I/O. That's a bit * unfortunate, but hopefully shouldn't happen often. */ if (vmbuffer == InvalidBuffer && PageIsAllVisible(page)) { LockBuffer(buffer, BUFFER_LOCK_UNLOCK); visibilitymap_pin(relation, block, &vmbuffer); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); } lp = PageGetItemId(page, ItemPointerGetOffsetNumber(tid)); Assert(ItemIdIsNormal(lp)); tp.t_data = (HeapTupleHeader) PageGetItem(page, 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 transaction-snapshot mode 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); if (vmbuffer != InvalidBuffer) ReleaseBuffer(vmbuffer); return result; } /* * We're about to do the actual delete -- check for conflict first, to * avoid possibly having to roll back work we've just done. */ CheckForSerializableConflictIn(relation, &tp, buffer); /* replace cid with a combo cid if necessary */ HeapTupleHeaderAdjustCmax(tp.t_data, &cid, &iscombo); START_CRIT_SECTION(); /* * If this transaction commits, the tuple will become DEAD sooner or * later. Set flag that this page is a candidate for pruning once our xid * falls below the OldestXmin horizon. If the transaction finally aborts, * the subsequent page pruning will be a no-op and the hint will be * cleared. */ PageSetPrunable(page, xid); if (PageIsAllVisible(page)) { all_visible_cleared = true; PageClearAllVisible(page); visibilitymap_clear(relation, BufferGetBlockNumber(buffer), vmbuffer); } /* 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); HeapTupleHeaderClearHotUpdated(tp.t_data); 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 (RelationNeedsWAL(relation)) { xl_heap_delete xlrec; XLogRecPtr recptr; XLogRecData rdata[2]; xlrec.all_visible_cleared = all_visible_cleared; 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(page, recptr); PageSetTLI(page, ThisTimeLineID); } END_CRIT_SECTION(); LockBuffer(buffer, BUFFER_LOCK_UNLOCK); if (vmbuffer != InvalidBuffer) ReleaseBuffer(vmbuffer); /* * 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_RELATION) { /* 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(true), 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, and its HEAP_ONLY_TUPLE flag is set iff a HOT * update was done. 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(); Bitmapset *hot_attrs; ItemId lp; HeapTupleData oldtup; HeapTuple heaptup; Page page; BlockNumber block; Buffer buffer, newbuf, vmbuffer = InvalidBuffer, vmbuffer_new = InvalidBuffer; bool need_toast, already_marked; Size newtupsize, pagefree; bool have_tuple_lock = false; bool iscombo; bool use_hot_update = false; bool all_visible_cleared = false; bool all_visible_cleared_new = false; Assert(ItemPointerIsValid(otid)); /* * Fetch the list of attributes to be checked for HOT update. This is * wasted effort if we fail to update or have to put the new tuple on a * different page. But we must compute the list before obtaining buffer * lock --- in the worst case, if we are doing an update on one of the * relevant system catalogs, we could deadlock if we try to fetch the list * later. In any case, the relcache caches the data so this is usually * pretty cheap. * * Note that we get a copy here, so we need not worry about relcache flush * happening midway through. */ hot_attrs = RelationGetIndexAttrBitmap(relation); block = ItemPointerGetBlockNumber(otid); buffer = ReadBuffer(relation, block); page = BufferGetPage(buffer); /* * Before locking the buffer, pin the visibility map page if it appears * to be necessary. Since we haven't got the lock yet, someone else might * be in the middle of changing this, so we'll need to recheck after * we have the lock. */ if (PageIsAllVisible(page)) visibilitymap_pin(relation, block, &vmbuffer); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); /* * If we didn't pin the visibility map page and the page has become all * visible while we were busy locking the buffer, we'll have to unlock and * re-lock, to avoid holding the buffer lock across an I/O. That's a bit * unfortunate, but hopefully shouldn't happen often. */ if (vmbuffer == InvalidBuffer && PageIsAllVisible(page)) { LockBuffer(buffer, BUFFER_LOCK_UNLOCK); visibilitymap_pin(relation, block, &vmbuffer); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); } lp = PageGetItemId(page, ItemPointerGetOffsetNumber(otid)); Assert(ItemIdIsNormal(lp)); oldtup.t_data = (HeapTupleHeader) PageGetItem(page, 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 transaction-snapshot mode 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); if (vmbuffer != InvalidBuffer) ReleaseBuffer(vmbuffer); bms_free(hot_attrs); return result; } /* * We're about to do the actual update -- check for conflict first, to * avoid possibly having to roll back work we've just done. */ CheckForSerializableConflictIn(relation, &oldtup, buffer); /* 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_infomask2 &= ~(HEAP2_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 */ newtup->t_tableOid = RelationGetRelid(relation); /* * 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_RELATION) { /* 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 = PageGetHeapFreeSpace(page); newtupsize = MAXALIGN(newtup->t_len); if (need_toast || newtupsize > pagefree) { /* Clear obsolete visibility flags ... */ oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | HEAP_XMAX_IS_MULTI | HEAP_IS_LOCKED | HEAP_MOVED); HeapTupleClearHotUpdated(&oldtup); /* ... and store info about transaction updating this tuple */ 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, 0); 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, 0, NULL, &vmbuffer_new); } 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 = PageGetHeapFreeSpace(page); 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, 0, NULL, &vmbuffer_new); } 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; } /* * We're about to create the new tuple -- check for conflict first, to * avoid possibly having to roll back work we've just done. * * NOTE: For a tuple insert, we only need to check for table locks, since * predicate locking at the index level will cover ranges for anything * except a table scan. Therefore, only provide the relation. */ CheckForSerializableConflictIn(relation, NULL, InvalidBuffer); /* * 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. */ if (newbuf == buffer) { /* * Since the new tuple is going into the same page, we might be able * to do a HOT update. Check if any of the index columns have been * changed. If not, then HOT update is possible. */ if (HeapSatisfiesHOTUpdate(relation, hot_attrs, &oldtup, heaptup)) use_hot_update = true; } else { /* Set a hint that the old page could use prune/defrag */ PageSetFull(page); } /* NO EREPORT(ERROR) from here till changes are logged */ START_CRIT_SECTION(); /* * If this transaction commits, the old tuple will become DEAD sooner or * later. Set flag that this page is a candidate for pruning once our xid * falls below the OldestXmin horizon. If the transaction finally aborts, * the subsequent page pruning will be a no-op and the hint will be * cleared. * * XXX Should we set hint on newbuf as well? If the transaction aborts, * there would be a prunable tuple in the newbuf; but for now we choose * not to optimize for aborts. Note that heap_xlog_update must be kept in * sync if this decision changes. */ PageSetPrunable(page, xid); if (use_hot_update) { /* Mark the old tuple as HOT-updated */ HeapTupleSetHotUpdated(&oldtup); /* And mark the new tuple as heap-only */ HeapTupleSetHeapOnly(heaptup); /* Mark the caller's copy too, in case different from heaptup */ HeapTupleSetHeapOnly(newtup); } else { /* Make sure tuples are correctly marked as not-HOT */ HeapTupleClearHotUpdated(&oldtup); HeapTupleClearHeapOnly(heaptup); HeapTupleClearHeapOnly(newtup); } RelationPutHeapTuple(relation, newbuf, heaptup); /* insert new tuple */ if (!already_marked) { /* Clear obsolete visibility flags ... */ oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | HEAP_XMAX_IS_MULTI | HEAP_IS_LOCKED | HEAP_MOVED); /* ... and store info about transaction updating this tuple */ 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; /* clear PD_ALL_VISIBLE flags */ if (PageIsAllVisible(BufferGetPage(buffer))) { all_visible_cleared = true; PageClearAllVisible(BufferGetPage(buffer)); } if (newbuf != buffer && PageIsAllVisible(BufferGetPage(newbuf))) { all_visible_cleared_new = true; PageClearAllVisible(BufferGetPage(newbuf)); } if (newbuf != buffer) MarkBufferDirty(newbuf); MarkBufferDirty(buffer); /* XLOG stuff */ if (RelationNeedsWAL(relation)) { XLogRecPtr recptr = log_heap_update(relation, buffer, oldtup.t_self, newbuf, heaptup, all_visible_cleared, all_visible_cleared_new); 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); /* Clear bits in visibility map */ if (all_visible_cleared) visibilitymap_clear(relation, BufferGetBlockNumber(buffer), vmbuffer); if (all_visible_cleared_new) visibilitymap_clear(relation, BufferGetBlockNumber(newbuf), vmbuffer_new); /* Now we can release the buffer(s) */ if (newbuf != buffer) ReleaseBuffer(newbuf); ReleaseBuffer(buffer); if (BufferIsValid(vmbuffer_new)) ReleaseBuffer(vmbuffer_new); if (BufferIsValid(vmbuffer)) ReleaseBuffer(vmbuffer); /* * 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, use_hot_update); /* * 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); } bms_free(hot_attrs); return HeapTupleMayBeUpdated; } /* * Check if the specified attribute's value is same in both given tuples. * Subroutine for HeapSatisfiesHOTUpdate. */ static bool heap_tuple_attr_equals(TupleDesc tupdesc, int attrnum, HeapTuple tup1, HeapTuple tup2) { Datum value1, value2; bool isnull1, isnull2; Form_pg_attribute att; /* * If it's a whole-tuple reference, say "not equal". It's not really * worth supporting this case, since it could only succeed after a no-op * update, which is hardly a case worth optimizing for. */ if (attrnum == 0) return false; /* * Likewise, automatically say "not equal" for any system attribute other * than OID and tableOID; we cannot expect these to be consistent in a HOT * chain, or even to be set correctly yet in the new tuple. */ if (attrnum < 0) { if (attrnum != ObjectIdAttributeNumber && attrnum != TableOidAttributeNumber) return false; } /* * Extract the corresponding values. XXX this is pretty inefficient if * there are many indexed columns. Should HeapSatisfiesHOTUpdate do a * single heap_deform_tuple call on each tuple, instead? But that doesn't * work for system columns ... */ value1 = heap_getattr(tup1, attrnum, tupdesc, &isnull1); value2 = heap_getattr(tup2, attrnum, tupdesc, &isnull2); /* * If one value is NULL and other is not, then they are certainly not * equal */ if (isnull1 != isnull2) return false; /* * If both are NULL, they can be considered equal. */ if (isnull1) return true; /* * We do simple binary comparison of the two datums. This may be overly * strict because there can be multiple binary representations for the * same logical value. But we should be OK as long as there are no false * positives. Using a type-specific equality operator is messy because * there could be multiple notions of equality in different operator * classes; furthermore, we cannot safely invoke user-defined functions * while holding exclusive buffer lock. */ if (attrnum <= 0) { /* The only allowed system columns are OIDs, so do this */ return (DatumGetObjectId(value1) == DatumGetObjectId(value2)); } else { Assert(attrnum <= tupdesc->natts); att = tupdesc->attrs[attrnum - 1]; return datumIsEqual(value1, value2, att->attbyval, att->attlen); } } /* * Check if the old and new tuples represent a HOT-safe update. To be able * to do a HOT update, we must not have changed any columns used in index * definitions. * * The set of attributes to be checked is passed in (we dare not try to * compute it while holding exclusive buffer lock...) NOTE that hot_attrs * is destructively modified! That is OK since this is invoked at most once * by heap_update(). * * Returns true if safe to do HOT update. */ static bool HeapSatisfiesHOTUpdate(Relation relation, Bitmapset *hot_attrs, HeapTuple oldtup, HeapTuple newtup) { int attrnum; while ((attrnum = bms_first_member(hot_attrs)) >= 0) { /* Adjust for system attributes */ attrnum += FirstLowInvalidHeapAttributeNumber; /* If the attribute value has changed, we can't do HOT update */ if (!heap_tuple_attr_equals(RelationGetDescr(relation), attrnum, oldtup, newtup)) return false; } return true; } /* * 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(true), 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; Page page; 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); page = BufferGetPage(*buffer); lp = PageGetItemId(page, ItemPointerGetOffsetNumber(tid)); Assert(ItemIdIsNormal(lp)); tuple->t_data = (HeapTupleHeader) PageGetItem(page, 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; HeapTupleHeaderClearHotUpdated(tuple->t_data); 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 (RelationNeedsWAL(relation)) { 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(page, recptr); PageSetTLI(page, ThisTimeLineID); } END_CRIT_SECTION(); LockBuffer(*buffer, BUFFER_LOCK_UNLOCK); /* * Don't update the visibility map here. Locking a tuple doesn't change * visibility info. */ /* * 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 || !ItemIdIsNormal(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 (RelationNeedsWAL(relation)) { 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; HeapTupleHeaderClearHotUpdated(tuple); 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 old-style VACUUM FULL, 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. * * Old-style VACUUM FULL is gone, but we have to keep this code as long as * we support having MOVED_OFF/MOVED_IN tuples in the database. */ 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); } } /* * If 'tuple' contains any visible XID greater than latestRemovedXid, * ratchet forwards latestRemovedXid to the greatest one found. * This is used as the basis for generating Hot Standby conflicts, so * if a tuple was never visible then removing it should not conflict * with queries. */ void HeapTupleHeaderAdvanceLatestRemovedXid(HeapTupleHeader tuple, TransactionId *latestRemovedXid) { TransactionId xmin = HeapTupleHeaderGetXmin(tuple); TransactionId xmax = HeapTupleHeaderGetXmax(tuple); TransactionId xvac = HeapTupleHeaderGetXvac(tuple); if (tuple->t_infomask & HEAP_MOVED) { if (TransactionIdPrecedes(*latestRemovedXid, xvac)) *latestRemovedXid = xvac; } /* * Ignore tuples inserted by an aborted transaction or if the tuple was * updated/deleted by the inserting transaction. * * Look for a committed hint bit, or if no xmin bit is set, check clog. * This needs to work on both master and standby, where it is used to * assess btree delete records. */ if ((tuple->t_infomask & HEAP_XMIN_COMMITTED) || (!(tuple->t_infomask & HEAP_XMIN_COMMITTED) && !(tuple->t_infomask & HEAP_XMIN_INVALID) && TransactionIdDidCommit(xmin))) { if (xmax != xmin && TransactionIdFollows(xmax, *latestRemovedXid)) *latestRemovedXid = xmax; } /* *latestRemovedXid may still be invalid at end */ } /* * Perform XLogInsert to register a heap cleanup info message. These * messages are sent once per VACUUM and are required because * of the phasing of removal operations during a lazy VACUUM. * see comments for vacuum_log_cleanup_info(). */ XLogRecPtr log_heap_cleanup_info(RelFileNode rnode, TransactionId latestRemovedXid) { xl_heap_cleanup_info xlrec; XLogRecPtr recptr; XLogRecData rdata; xlrec.node = rnode; xlrec.latestRemovedXid = latestRemovedXid; rdata.data = (char *) &xlrec; rdata.len = SizeOfHeapCleanupInfo; rdata.buffer = InvalidBuffer; rdata.next = NULL; recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_CLEANUP_INFO, &rdata); return recptr; } /* * Perform XLogInsert for a heap-clean operation. Caller must already * have modified the buffer and marked it dirty. * * Note: prior to Postgres 8.3, the entries in the nowunused[] array were * zero-based tuple indexes. Now they are one-based like other uses * of OffsetNumber. * * We also include latestRemovedXid, which is the greatest XID present in * the removed tuples. That allows recovery processing to cancel or wait * for long standby queries that can still see these tuples. */ XLogRecPtr log_heap_clean(Relation reln, Buffer buffer, OffsetNumber *redirected, int nredirected, OffsetNumber *nowdead, int ndead, OffsetNumber *nowunused, int nunused, TransactionId latestRemovedXid) { xl_heap_clean xlrec; uint8 info; XLogRecPtr recptr; XLogRecData rdata[4]; /* Caller should not call me on a non-WAL-logged relation */ Assert(RelationNeedsWAL(reln)); xlrec.node = reln->rd_node; xlrec.block = BufferGetBlockNumber(buffer); xlrec.latestRemovedXid = latestRemovedXid; xlrec.nredirected = nredirected; xlrec.ndead = ndead; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapClean; rdata[0].buffer = InvalidBuffer; rdata[0].next = &(rdata[1]); /* * The OffsetNumber arrays are not actually in the buffer, but we pretend * that they are. When XLogInsert stores the whole buffer, the offset * arrays need not be stored too. Note that even if all three arrays are * empty, we want to expose the buffer as a candidate for whole-page * storage, since this record type implies a defragmentation operation * even if no item pointers changed state. */ if (nredirected > 0) { rdata[1].data = (char *) redirected; rdata[1].len = nredirected * sizeof(OffsetNumber) * 2; } else { rdata[1].data = NULL; rdata[1].len = 0; } rdata[1].buffer = buffer; rdata[1].buffer_std = true; rdata[1].next = &(rdata[2]); if (ndead > 0) { rdata[2].data = (char *) nowdead; rdata[2].len = ndead * sizeof(OffsetNumber); } else { rdata[2].data = NULL; rdata[2].len = 0; } rdata[2].buffer = buffer; rdata[2].buffer_std = true; rdata[2].next = &(rdata[3]); if (nunused > 0) { rdata[3].data = (char *) nowunused; rdata[3].len = nunused * sizeof(OffsetNumber); } else { rdata[3].data = NULL; rdata[3].len = 0; } rdata[3].buffer = buffer; rdata[3].buffer_std = true; rdata[3].next = NULL; info = XLOG_HEAP2_CLEAN; recptr = XLogInsert(RM_HEAP2_ID, info, rdata); return recptr; } /* * Perform XLogInsert for a heap-freeze operation. Caller must already * have modified the buffer and marked it dirty. */ 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 non-WAL-logged relation */ Assert(RelationNeedsWAL(reln)); /* nor when there are no tuples to freeze */ Assert(offcnt > 0); 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. */ rdata[1].data = (char *) offsets; rdata[1].len = offcnt * sizeof(OffsetNumber); 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-visible operation. 'block' is the block * being marked all-visible, and vm_buffer is the buffer containing the * corresponding visibility map block. Both should have already been modified * and dirtied. */ XLogRecPtr log_heap_visible(RelFileNode rnode, BlockNumber block, Buffer vm_buffer) { xl_heap_visible xlrec; XLogRecPtr recptr; XLogRecData rdata[2]; xlrec.node = rnode; xlrec.block = block; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfHeapVisible; rdata[0].buffer = InvalidBuffer; rdata[0].next = &(rdata[1]); rdata[1].data = NULL; rdata[1].len = 0; rdata[1].buffer = vm_buffer; rdata[1].buffer_std = false; rdata[1].next = NULL; recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_VISIBLE, 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 all_visible_cleared, bool new_all_visible_cleared) { xl_heap_update xlrec; xl_heap_header xlhdr; uint8 info; XLogRecPtr recptr; XLogRecData rdata[4]; Page page = BufferGetPage(newbuf); /* Caller should not call me on a non-WAL-logged relation */ Assert(RelationNeedsWAL(reln)); if (HeapTupleIsHeapOnly(newtup)) info = XLOG_HEAP_HOT_UPDATE; else info = XLOG_HEAP_UPDATE; xlrec.target.node = reln->rd_node; xlrec.target.tid = from; xlrec.all_visible_cleared = all_visible_cleared; xlrec.newtid = newtup->t_self; xlrec.new_all_visible_cleared = new_all_visible_cleared; 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.t_infomask2 = newtup->t_data->t_infomask2; xlhdr.t_infomask = newtup->t_data->t_infomask; xlhdr.t_hoff = newtup->t_data->t_hoff; /* * 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 = SizeOfHeapHeader; 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 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, ForkNumber forkNum, 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.forknum = forkNum; 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); /* * The page may be uninitialized. If so, we can't set the LSN and TLI * because that would corrupt the page. */ if (!PageIsNew(page)) { PageSetLSN(page, recptr); PageSetTLI(page, ThisTimeLineID); } END_CRIT_SECTION(); return recptr; } /* * Handles CLEANUP_INFO */ static void heap_xlog_cleanup_info(XLogRecPtr lsn, XLogRecord *record) { xl_heap_cleanup_info *xlrec = (xl_heap_cleanup_info *) XLogRecGetData(record); if (InHotStandby) ResolveRecoveryConflictWithSnapshot(xlrec->latestRemovedXid, xlrec->node); /* * Actual operation is a no-op. Record type exists to provide a means for * conflict processing to occur before we begin index vacuum actions. see * vacuumlazy.c and also comments in btvacuumpage() */ } /* * Handles HEAP2_CLEAN record type */ static void heap_xlog_clean(XLogRecPtr lsn, XLogRecord *record) { xl_heap_clean *xlrec = (xl_heap_clean *) XLogRecGetData(record); Buffer buffer; Page page; OffsetNumber *end; OffsetNumber *redirected; OffsetNumber *nowdead; OffsetNumber *nowunused; int nredirected; int ndead; int nunused; Size freespace; /* * We're about to remove tuples. In Hot Standby mode, ensure that there's * no queries running for which the removed tuples are still visible. * * Not all HEAP2_CLEAN records remove tuples with xids, so we only want to * conflict on the records that cause MVCC failures for user queries. If * latestRemovedXid is invalid, skip conflict processing. */ if (InHotStandby && TransactionIdIsValid(xlrec->latestRemovedXid)) ResolveRecoveryConflictWithSnapshot(xlrec->latestRemovedXid, xlrec->node); RestoreBkpBlocks(lsn, record, true); if (record->xl_info & XLR_BKP_BLOCK_1) return; buffer = XLogReadBufferExtended(xlrec->node, MAIN_FORKNUM, xlrec->block, RBM_NORMAL); if (!BufferIsValid(buffer)) return; LockBufferForCleanup(buffer); page = (Page) BufferGetPage(buffer); if (XLByteLE(lsn, PageGetLSN(page))) { UnlockReleaseBuffer(buffer); return; } nredirected = xlrec->nredirected; ndead = xlrec->ndead; end = (OffsetNumber *) ((char *) xlrec + record->xl_len); redirected = (OffsetNumber *) ((char *) xlrec + SizeOfHeapClean); nowdead = redirected + (nredirected * 2); nowunused = nowdead + ndead; nunused = (end - nowunused); Assert(nunused >= 0); /* Update all item pointers per the record, and repair fragmentation */ heap_page_prune_execute(buffer, redirected, nredirected, nowdead, ndead, nowunused, nunused); freespace = PageGetHeapFreeSpace(page); /* needed to update FSM below */ /* * Note: we don't worry about updating the page's prunability hints. At * worst this will cause an extra prune cycle to occur soon. */ PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); /* * Update the FSM as well. * * XXX: We don't get here if the page was restored from full page image. * We don't bother to update the FSM in that case, it doesn't need to be * totally accurate anyway. */ XLogRecordPageWithFreeSpace(xlrec->node, xlrec->block, freespace); } static void heap_xlog_freeze(XLogRecPtr lsn, XLogRecord *record) { xl_heap_freeze *xlrec = (xl_heap_freeze *) XLogRecGetData(record); TransactionId cutoff_xid = xlrec->cutoff_xid; Buffer buffer; Page page; /* * In Hot Standby mode, ensure that there's no queries running which still * consider the frozen xids as running. */ if (InHotStandby) ResolveRecoveryConflictWithSnapshot(cutoff_xid, xlrec->node); RestoreBkpBlocks(lsn, record, false); if (record->xl_info & XLR_BKP_BLOCK_1) return; buffer = XLogReadBufferExtended(xlrec->node, MAIN_FORKNUM, xlrec->block, RBM_NORMAL); if (!BufferIsValid(buffer)) return; LockBufferForCleanup(buffer); 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); } /* * Replay XLOG_HEAP2_VISIBLE record. * * The critical integrity requirement here is that we must never end up with * a situation where the visibility map bit is set, and the page-level * PD_ALL_VISIBLE bit is clear. If that were to occur, then a subsequent * page modification would fail to clear the visibility map bit. */ static void heap_xlog_visible(XLogRecPtr lsn, XLogRecord *record) { xl_heap_visible *xlrec = (xl_heap_visible *) XLogRecGetData(record); Buffer buffer; Page page; /* * Read the heap page, if it still exists. If the heap file has been * dropped or truncated later in recovery, this might fail. In that case, * there's no point in doing anything further, since the visibility map * will have to be cleared out at the same time. */ buffer = XLogReadBufferExtended(xlrec->node, MAIN_FORKNUM, xlrec->block, RBM_NORMAL); if (!BufferIsValid(buffer)) return; page = (Page) BufferGetPage(buffer); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); /* * We don't bump the LSN of the heap page when setting the visibility * map bit, because that would generate an unworkable volume of * full-page writes. This exposes us to torn page hazards, but since * we're not inspecting the existing page contents in any way, we * don't care. * * However, all operations that clear the visibility map bit *do* bump * the LSN, and those operations will only be replayed if the XLOG LSN * follows the page LSN. Thus, if the page LSN has advanced past our * XLOG record's LSN, we mustn't mark the page all-visible, because * the subsequent update won't be replayed to clear the flag. */ if (!XLByteLE(lsn, PageGetLSN(page))) { PageSetAllVisible(page); MarkBufferDirty(buffer); } /* Done with heap page. */ UnlockReleaseBuffer(buffer); /* * Even we skipped the heap page update due to the LSN interlock, it's * still safe to update the visibility map. Any WAL record that clears * the visibility map bit does so before checking the page LSN, so any * bits that need to be cleared will still be cleared. */ if (record->xl_info & XLR_BKP_BLOCK_1) RestoreBkpBlocks(lsn, record, false); else { Relation reln; Buffer vmbuffer = InvalidBuffer; reln = CreateFakeRelcacheEntry(xlrec->node); visibilitymap_pin(reln, xlrec->block, &vmbuffer); /* * Don't set the bit if replay has already passed this point. * * It might be safe to do this unconditionally; if replay has past * this point, we'll replay at least as far this time as we did before, * and if this bit needs to be cleared, the record responsible for * doing so should be again replayed, and clear it. For right now, * out of an abundance of conservatism, we use the same test here * we did for the heap page; if this results in a dropped bit, no real * harm is done; and the next VACUUM will fix it. */ if (!XLByteLE(lsn, PageGetLSN(BufferGetPage(vmbuffer)))) visibilitymap_set(reln, xlrec->block, lsn, vmbuffer); ReleaseBuffer(vmbuffer); FreeFakeRelcacheEntry(reln); } } static void heap_xlog_newpage(XLogRecPtr lsn, XLogRecord *record) { xl_heap_newpage *xlrec = (xl_heap_newpage *) XLogRecGetData(record); 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. */ buffer = XLogReadBufferExtended(xlrec->node, xlrec->forknum, xlrec->blkno, RBM_ZERO); Assert(BufferIsValid(buffer)); LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); page = (Page) BufferGetPage(buffer); Assert(record->xl_len == SizeOfHeapNewpage + BLCKSZ); memcpy(page, (char *) xlrec + SizeOfHeapNewpage, BLCKSZ); /* * The page may be uninitialized. If so, we can't set the LSN and TLI * because that would corrupt the page. */ if (!PageIsNew(page)) { 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); Buffer buffer; Page page; OffsetNumber offnum; ItemId lp = NULL; HeapTupleHeader htup; BlockNumber blkno; blkno = ItemPointerGetBlockNumber(&(xlrec->target.tid)); /* * The visibility map may need to be fixed even if the heap page is * already up-to-date. */ if (xlrec->all_visible_cleared) { Relation reln = CreateFakeRelcacheEntry(xlrec->target.node); Buffer vmbuffer = InvalidBuffer; visibilitymap_pin(reln, blkno, &vmbuffer); visibilitymap_clear(reln, blkno, vmbuffer); ReleaseBuffer(vmbuffer); FreeFakeRelcacheEntry(reln); } if (record->xl_info & XLR_BKP_BLOCK_1) return; buffer = XLogReadBuffer(xlrec->target.node, blkno, 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 || !ItemIdIsNormal(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); HeapTupleHeaderClearHotUpdated(htup); HeapTupleHeaderSetXmax(htup, record->xl_xid); HeapTupleHeaderSetCmax(htup, FirstCommandId, false); /* Mark the page as a candidate for pruning */ PageSetPrunable(page, record->xl_xid); if (xlrec->all_visible_cleared) PageClearAllVisible(page); /* 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); Buffer buffer; Page page; OffsetNumber offnum; struct { HeapTupleHeaderData hdr; char data[MaxHeapTupleSize]; } tbuf; HeapTupleHeader htup; xl_heap_header xlhdr; uint32 newlen; Size freespace; BlockNumber blkno; blkno = ItemPointerGetBlockNumber(&(xlrec->target.tid)); /* * The visibility map may need to be fixed even if the heap page is * already up-to-date. */ if (xlrec->all_visible_cleared) { Relation reln = CreateFakeRelcacheEntry(xlrec->target.node); Buffer vmbuffer = InvalidBuffer; visibilitymap_pin(reln, blkno, &vmbuffer); visibilitymap_clear(reln, blkno, vmbuffer); ReleaseBuffer(vmbuffer); FreeFakeRelcacheEntry(reln); } if (record->xl_info & XLR_BKP_BLOCK_1) return; if (record->xl_info & XLOG_HEAP_INIT_PAGE) { buffer = XLogReadBuffer(xlrec->target.node, blkno, true); Assert(BufferIsValid(buffer)); page = (Page) BufferGetPage(buffer); PageInit(page, BufferGetPageSize(buffer), 0); } else { buffer = XLogReadBuffer(xlrec->target.node, blkno, 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, true, true); if (offnum == InvalidOffsetNumber) elog(PANIC, "heap_insert_redo: failed to add tuple"); freespace = PageGetHeapFreeSpace(page); /* needed to update FSM below */ PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); if (xlrec->all_visible_cleared) PageClearAllVisible(page); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); /* * If the page is running low on free space, update the FSM as well. * Arbitrarily, our definition of "low" is less than 20%. We can't do much * better than that without knowing the fill-factor for the table. * * XXX: We don't get here if the page was restored from full page image. * We don't bother to update the FSM in that case, it doesn't need to be * totally accurate anyway. */ if (freespace < BLCKSZ / 5) XLogRecordPageWithFreeSpace(xlrec->target.node, blkno, freespace); } /* * Handles UPDATE and HOT_UPDATE */ static void heap_xlog_update(XLogRecPtr lsn, XLogRecord *record, bool hot_update) { xl_heap_update *xlrec = (xl_heap_update *) XLogRecGetData(record); 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; Size freespace; /* * The visibility map may need to be fixed even if the heap page is * already up-to-date. */ if (xlrec->all_visible_cleared) { Relation reln = CreateFakeRelcacheEntry(xlrec->target.node); BlockNumber block = ItemPointerGetBlockNumber(&xlrec->target.tid); Buffer vmbuffer = InvalidBuffer; visibilitymap_pin(reln, block, &vmbuffer); visibilitymap_clear(reln, block, vmbuffer); ReleaseBuffer(vmbuffer); FreeFakeRelcacheEntry(reln); } 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(xlrec->target.node, 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 || !ItemIdIsNormal(lp)) elog(PANIC, "heap_update_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 (hot_update) HeapTupleHeaderSetHotUpdated(htup); else HeapTupleHeaderClearHotUpdated(htup); HeapTupleHeaderSetXmax(htup, record->xl_xid); HeapTupleHeaderSetCmax(htup, FirstCommandId, false); /* Set forward chain link in t_ctid */ htup->t_ctid = xlrec->newtid; /* Mark the page as a candidate for pruning */ PageSetPrunable(page, record->xl_xid); if (xlrec->all_visible_cleared) PageClearAllVisible(page); /* * 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:; /* * The visibility map may need to be fixed even if the heap page is * already up-to-date. */ if (xlrec->new_all_visible_cleared) { Relation reln = CreateFakeRelcacheEntry(xlrec->target.node); BlockNumber block = ItemPointerGetBlockNumber(&xlrec->newtid); Buffer vmbuffer = InvalidBuffer; visibilitymap_pin(reln, block, &vmbuffer); visibilitymap_clear(reln, block, vmbuffer); ReleaseBuffer(vmbuffer); FreeFakeRelcacheEntry(reln); } if (record->xl_info & XLR_BKP_BLOCK_2) return; if (record->xl_info & XLOG_HEAP_INIT_PAGE) { buffer = XLogReadBuffer(xlrec->target.node, ItemPointerGetBlockNumber(&(xlrec->newtid)), true); Assert(BufferIsValid(buffer)); page = (Page) BufferGetPage(buffer); PageInit(page, BufferGetPageSize(buffer), 0); } else { buffer = XLogReadBuffer(xlrec->target.node, 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; 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; 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, true, true); if (offnum == InvalidOffsetNumber) elog(PANIC, "heap_update_redo: failed to add tuple"); if (xlrec->new_all_visible_cleared) PageClearAllVisible(page); freespace = PageGetHeapFreeSpace(page); /* needed to update FSM below */ PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); /* * If the page is running low on free space, update the FSM as well. * Arbitrarily, our definition of "low" is less than 20%. We can't do much * better than that without knowing the fill-factor for the table. * * However, don't update the FSM on HOT updates, because after crash * recovery, either the old or the new tuple will certainly be dead and * prunable. After pruning, the page will have roughly as much free space * as it did before the update, assuming the new tuple is about the same * size as the old one. * * XXX: We don't get here if the page was restored from full page image. * We don't bother to update the FSM in that case, it doesn't need to be * totally accurate anyway. */ if (!hot_update && freespace < BLCKSZ / 5) XLogRecordPageWithFreeSpace(xlrec->target.node, ItemPointerGetBlockNumber(&(xlrec->newtid)), freespace); } static void heap_xlog_lock(XLogRecPtr lsn, XLogRecord *record) { xl_heap_lock *xlrec = (xl_heap_lock *) XLogRecGetData(record); Buffer buffer; Page page; OffsetNumber offnum; ItemId lp = NULL; HeapTupleHeader htup; if (record->xl_info & XLR_BKP_BLOCK_1) return; buffer = XLogReadBuffer(xlrec->target.node, 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 || !ItemIdIsNormal(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; HeapTupleHeaderClearHotUpdated(htup); 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); 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(xlrec->target.node, 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 || !ItemIdIsNormal(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; /* * These operations don't overwrite MVCC data so no conflict processing is * required. The ones in heap2 rmgr do. */ RestoreBkpBlocks(lsn, record, false); switch (info & XLOG_HEAP_OPMASK) { case XLOG_HEAP_INSERT: heap_xlog_insert(lsn, record); break; case XLOG_HEAP_DELETE: heap_xlog_delete(lsn, record); break; case XLOG_HEAP_UPDATE: heap_xlog_update(lsn, record, false); break; case XLOG_HEAP_HOT_UPDATE: heap_xlog_update(lsn, record, true); break; case XLOG_HEAP_NEWPAGE: heap_xlog_newpage(lsn, record); break; case XLOG_HEAP_LOCK: heap_xlog_lock(lsn, record); break; case XLOG_HEAP_INPLACE: heap_xlog_inplace(lsn, record); break; default: elog(PANIC, "heap_redo: unknown op code %u", info); } } void heap2_redo(XLogRecPtr lsn, XLogRecord *record) { uint8 info = record->xl_info & ~XLR_INFO_MASK; /* * Note that RestoreBkpBlocks() is called after conflict processing within * each record type handling function. */ switch (info & XLOG_HEAP_OPMASK) { case XLOG_HEAP2_FREEZE: heap_xlog_freeze(lsn, record); break; case XLOG_HEAP2_CLEAN: heap_xlog_clean(lsn, record); break; case XLOG_HEAP2_CLEANUP_INFO: heap_xlog_cleanup_info(lsn, record); break; case XLOG_HEAP2_VISIBLE: heap_xlog_visible(lsn, record); break; default: 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_HOT_UPDATE) { xl_heap_update *xlrec = (xl_heap_update *) rec; if (xl_info & XLOG_HEAP_INIT_PAGE) /* can this case happen? */ appendStringInfo(buf, "hot_update(init): "); else appendStringInfo(buf, "hot_update: "); out_target(buf, &(xlrec->target)); appendStringInfo(buf, "; new %u/%u", ItemPointerGetBlockNumber(&(xlrec->newtid)), ItemPointerGetOffsetNumber(&(xlrec->newtid))); } else if (info == XLOG_HEAP_NEWPAGE) { xl_heap_newpage *xlrec = (xl_heap_newpage *) rec; appendStringInfo(buf, "newpage: rel %u/%u/%u; fork %u, blk %u", xlrec->node.spcNode, xlrec->node.dbNode, xlrec->node.relNode, xlrec->forknum, 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 if (info == XLOG_HEAP2_CLEAN) { xl_heap_clean *xlrec = (xl_heap_clean *) rec; appendStringInfo(buf, "clean: rel %u/%u/%u; blk %u remxid %u", xlrec->node.spcNode, xlrec->node.dbNode, xlrec->node.relNode, xlrec->block, xlrec->latestRemovedXid); } else if (info == XLOG_HEAP2_CLEANUP_INFO) { xl_heap_cleanup_info *xlrec = (xl_heap_cleanup_info *) rec; appendStringInfo(buf, "cleanup info: remxid %u", xlrec->latestRemovedXid); } else if (info == XLOG_HEAP2_VISIBLE) { xl_heap_visible *xlrec = (xl_heap_visible *) rec; appendStringInfo(buf, "visible: rel %u/%u/%u; blk %u", xlrec->node.spcNode, xlrec->node.dbNode, xlrec->node.relNode, xlrec->block); } 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 WAL is otherwise needed, 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) { /* non-WAL-logged tables never need fsync */ if (!RelationNeedsWAL(rel)) return; /* main heap */ FlushRelationBuffers(rel); /* FlushRelationBuffers will have opened rd_smgr */ smgrimmedsync(rel->rd_smgr, MAIN_FORKNUM); /* FSM is not critical, don't bother syncing it */ /* 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, MAIN_FORKNUM); heap_close(toastrel, AccessShareLock); } }