#include "postgres.h"
#include "access/nbtree.h"
#include "access/nbtxlog.h"
#include "access/tableam.h"
#include "access/transam.h"
#include "access/xlog.h"
#include "access/xloginsert.h"
#include "miscadmin.h"
#include "storage/indexfsm.h"
#include "storage/lmgr.h"
#include "storage/predicate.h"
#include "storage/procarray.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
#include "utils/snapmgr.h"

Include dependency graph for nbtpage.c:

Functions
static BTMetaPageData *	_bt_getmeta (Relation rel, Buffer metabuf)

static void	_bt_log_reuse_page (Relation rel, BlockNumber blkno, FullTransactionId safexid)

static void	_bt_delitems_delete (Relation rel, Buffer buf, TransactionId snapshotConflictHorizon, OffsetNumber deletable, int ndeletable, BTVacuumPosting updatable, int nupdatable)

static char *	_bt_delitems_update (BTVacuumPosting updatable, int nupdatable, OffsetNumber updatedoffsets, Size *updatedbuflen, bool needswal)

static bool	_bt_mark_page_halfdead (Relation rel, Buffer leafbuf, BTStack stack)

static bool	_bt_unlink_halfdead_page (Relation rel, Buffer leafbuf, BlockNumber scanblkno, bool rightsib_empty, BTVacState vstate)

static bool	_bt_lock_subtree_parent (Relation rel, BlockNumber child, BTStack stack, Buffer subtreeparent, OffsetNumber poffset, BlockNumber topparent, BlockNumber topparentrightsib)

static void	_bt_pendingfsm_add (BTVacState *vstate, BlockNumber target, FullTransactionId safexid)

void	_bt_initmetapage (Page page, BlockNumber rootbknum, uint32 level, bool allequalimage)

void	_bt_upgrademetapage (Page page)

bool	_bt_vacuum_needs_cleanup (Relation rel)

void	_bt_set_cleanup_info (Relation rel, BlockNumber num_delpages)

Buffer	_bt_getroot (Relation rel, int access)

Buffer	_bt_gettrueroot (Relation rel)

int	_bt_getrootheight (Relation rel)

void	_bt_metaversion (Relation rel, bool heapkeyspace, bool allequalimage)

void	_bt_checkpage (Relation rel, Buffer buf)

Buffer	_bt_getbuf (Relation rel, BlockNumber blkno, int access)

Buffer	_bt_relandgetbuf (Relation rel, Buffer obuf, BlockNumber blkno, int access)

void	_bt_relbuf (Relation rel, Buffer buf)

void	_bt_lockbuf (Relation rel, Buffer buf, int access)

void	_bt_unlockbuf (Relation rel, Buffer buf)

bool	_bt_conditionallockbuf (Relation rel, Buffer buf)

void	_bt_upgradelockbufcleanup (Relation rel, Buffer buf)

void	_bt_pageinit (Page page, Size size)

void	_bt_delitems_vacuum (Relation rel, Buffer buf, OffsetNumber deletable, int ndeletable, BTVacuumPosting updatable, int nupdatable)

static int	_bt_delitems_cmp (const void a, const void b)

void	_bt_delitems_delete_check (Relation rel, Buffer buf, Relation heapRel, TM_IndexDeleteOp *delstate)

static bool	_bt_leftsib_splitflag (Relation rel, BlockNumber leftsib, BlockNumber target)

static bool	_bt_rightsib_halfdeadflag (Relation rel, BlockNumber leafrightsib)

void	_bt_pagedel (Relation rel, Buffer leafbuf, BTVacState *vstate)

void	_bt_pendingfsm_init (Relation rel, BTVacState *vstate, bool cleanuponly)

void	_bt_pendingfsm_finalize (Relation rel, BTVacState *vstate)

Function Documentation

◆ _bt_checkpage()

void _bt_checkpage	(	Relation	rel,
		Buffer	buf
	)

Definition at line 794 of file nbtpage.c.

 {
     Page        page = BufferGetPage(buf);
  
     /*
      * ReadBuffer verifies that every newly-read page passes
      * PageHeaderIsValid, which means it either contains a reasonably sane
      * page header or is all-zero.  We have to defend against the all-zero
      * case, however.
      */
     if (PageIsNew(page))
         ereport(ERROR,
                 (errcode(ERRCODE_INDEX_CORRUPTED),
                  errmsg("index \"%s\" contains unexpected zero page at block %u",
                         RelationGetRelationName(rel),
                         BufferGetBlockNumber(buf)),
                  errhint("Please REINDEX it.")));
  
     /*
      * Additionally check that the special area looks sane.
      */
     if (PageGetSpecialSize(page) != MAXALIGN(sizeof(BTPageOpaqueData)))
         ereport(ERROR,
                 (errcode(ERRCODE_INDEX_CORRUPTED),
                  errmsg("index \"%s\" contains corrupted page at block %u",
                         RelationGetRelationName(rel),
                         BufferGetBlockNumber(buf)),
                  errhint("Please REINDEX it.")));
 }

References buf, BufferGetBlockNumber(), BufferGetPage(), ereport, errcode(), errhint(), errmsg(), ERROR, MAXALIGN, PageGetSpecialSize(), PageIsNew(), and RelationGetRelationName.

Referenced by _bt_getbuf(), _bt_relandgetbuf(), _bt_search_insert(), bt_recheck_sibling_links(), btvacuumpage(), and palloc_btree_page().

◆ _bt_conditionallockbuf()

bool _bt_conditionallockbuf	(	Relation	rel,
		Buffer	buf
	)

Definition at line 1105 of file nbtpage.c.

 {
     /* ConditionalLockBuffer() asserts that pin is held by this backend */
     if (!ConditionalLockBuffer(buf))
         return false;
  
     if (!RelationUsesLocalBuffers(rel))
         VALGRIND_MAKE_MEM_DEFINED(BufferGetPage(buf), BLCKSZ);
  
     return true;
 }

References buf, BufferGetPage(), ConditionalLockBuffer(), RelationUsesLocalBuffers, and VALGRIND_MAKE_MEM_DEFINED.

Referenced by _bt_getbuf(), and _bt_search_insert().

◆ _bt_delitems_cmp()

static int _bt_delitems_cmp	(	const void *	a,
		const void *	b
	)

static

Definition at line 1475 of file nbtpage.c.

 {
     TM_IndexDelete *indexdelete1 = (TM_IndexDelete *) a;
     TM_IndexDelete *indexdelete2 = (TM_IndexDelete *) b;
  
     if (indexdelete1->id > indexdelete2->id)
         return 1;
     if (indexdelete1->id < indexdelete2->id)
         return -1;
  
     Assert(false);
  
     return 0;
 }

References a, Assert(), b, and TM_IndexDelete::id.

Referenced by _bt_delitems_delete_check().

◆ _bt_delitems_delete()

static void _bt_delitems_delete	(	Relation	rel,
		Buffer	buf,
		TransactionId	snapshotConflictHorizon,
		OffsetNumber *	deletable,
		int	ndeletable,
		BTVacuumPosting *	updatable,
		int	nupdatable
	)

static

Definition at line 1296 of file nbtpage.c.

 {
     Page        page = BufferGetPage(buf);
     BTPageOpaque opaque;
     bool        needswal = RelationNeedsWAL(rel);
     char       *updatedbuf = NULL;
     Size        updatedbuflen = 0;
     OffsetNumber updatedoffsets[MaxIndexTuplesPerPage];
  
     /* Shouldn't be called unless there's something to do */
     Assert(ndeletable > 0 || nupdatable > 0);
  
     /* Generate new versions of posting lists without deleted TIDs */
     if (nupdatable > 0)
         updatedbuf = _bt_delitems_update(updatable, nupdatable,
                                          updatedoffsets, &updatedbuflen,
                                          needswal);
  
     /* No ereport(ERROR) until changes are logged */
     START_CRIT_SECTION();
  
     /* Handle updates and deletes just like _bt_delitems_vacuum */
     for (int i = 0; i < nupdatable; i++)
     {
         OffsetNumber updatedoffset = updatedoffsets[i];
         IndexTuple  itup;
         Size        itemsz;
  
         itup = updatable[i]->itup;
         itemsz = MAXALIGN(IndexTupleSize(itup));
         if (!PageIndexTupleOverwrite(page, updatedoffset, (Item) itup,
                                      itemsz))
             elog(PANIC, "failed to update partially dead item in block %u of index \"%s\"",
                  BufferGetBlockNumber(buf), RelationGetRelationName(rel));
     }
  
     if (ndeletable > 0)
         PageIndexMultiDelete(page, deletable, ndeletable);
  
     /*
      * Unlike _bt_delitems_vacuum, we *must not* clear the vacuum cycle ID at
      * this point.  The VACUUM command alone controls vacuum cycle IDs.
      */
     opaque = BTPageGetOpaque(page);
  
     /*
      * Clear the BTP_HAS_GARBAGE page flag.
      *
      * This flag indicates the presence of LP_DEAD items on the page (though
      * not reliably).  Note that we only rely on it with pg_upgrade'd
      * !heapkeyspace indexes.
      */
     opaque->btpo_flags &= ~BTP_HAS_GARBAGE;
  
     MarkBufferDirty(buf);
  
     /* XLOG stuff */
     if (needswal)
     {
         XLogRecPtr  recptr;
         xl_btree_delete xlrec_delete;
  
         xlrec_delete.snapshotConflictHorizon = snapshotConflictHorizon;
         xlrec_delete.ndeleted = ndeletable;
         xlrec_delete.nupdated = nupdatable;
  
         XLogBeginInsert();
         XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
         XLogRegisterData((char *) &xlrec_delete, SizeOfBtreeDelete);
  
         if (ndeletable > 0)
             XLogRegisterBufData(0, (char *) deletable,
                                 ndeletable * sizeof(OffsetNumber));
  
         if (nupdatable > 0)
         {
             XLogRegisterBufData(0, (char *) updatedoffsets,
                                 nupdatable * sizeof(OffsetNumber));
             XLogRegisterBufData(0, updatedbuf, updatedbuflen);
         }
  
         recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_DELETE);
  
         PageSetLSN(page, recptr);
     }
  
     END_CRIT_SECTION();
  
     /* can't leak memory here */
     if (updatedbuf != NULL)
         pfree(updatedbuf);
     /* free tuples allocated within _bt_delitems_update() */
     for (int i = 0; i < nupdatable; i++)
         pfree(updatable[i]->itup);
 }

References _bt_delitems_update(), Assert(), BTP_HAS_GARBAGE, BTPageGetOpaque, BTPageOpaqueData::btpo_flags, buf, BufferGetBlockNumber(), BufferGetPage(), elog(), END_CRIT_SECTION, i, IndexTupleSize, BTVacuumPostingData::itup, MarkBufferDirty(), MAXALIGN, MaxIndexTuplesPerPage, xl_btree_delete::ndeleted, xl_btree_delete::nupdated, PageIndexMultiDelete(), PageIndexTupleOverwrite(), PageSetLSN(), PANIC, pfree(), REGBUF_STANDARD, RelationGetRelationName, RelationNeedsWAL, SizeOfBtreeDelete, xl_btree_delete::snapshotConflictHorizon, START_CRIT_SECTION, XLOG_BTREE_DELETE, XLogBeginInsert(), XLogInsert(), XLogRegisterBufData(), XLogRegisterBuffer(), and XLogRegisterData().

Referenced by _bt_delitems_delete_check().

◆ _bt_delitems_delete_check()

void _bt_delitems_delete_check	(	Relation	rel,
		Buffer	buf,
		Relation	heapRel,
		TM_IndexDeleteOp *	delstate
	)

Definition at line 1529 of file nbtpage.c.

 {
     Page        page = BufferGetPage(buf);
     TransactionId snapshotConflictHorizon;
     OffsetNumber postingidxoffnum = InvalidOffsetNumber;
     int         ndeletable = 0,
                 nupdatable = 0;
     OffsetNumber deletable[MaxIndexTuplesPerPage];
     BTVacuumPosting updatable[MaxIndexTuplesPerPage];
  
     /* Use tableam interface to determine which tuples to delete first */
     snapshotConflictHorizon = table_index_delete_tuples(heapRel, delstate);
  
     /* Should not WAL-log snapshotConflictHorizon unless it's required */
     if (!XLogStandbyInfoActive())
         snapshotConflictHorizon = InvalidTransactionId;
  
     /*
      * Construct a leaf-page-wise description of what _bt_delitems_delete()
      * needs to do to physically delete index tuples from the page.
      *
      * Must sort deltids array to restore leaf-page-wise order (original order
      * before call to tableam).  This is the order that the loop expects.
      *
      * Note that deltids array might be a lot smaller now.  It might even have
      * no entries at all (with bottom-up deletion caller), in which case there
      * is nothing left to do.
      */
     qsort(delstate->deltids, delstate->ndeltids, sizeof(TM_IndexDelete),
           _bt_delitems_cmp);
     if (delstate->ndeltids == 0)
     {
         Assert(delstate->bottomup);
         return;
     }
  
     /* We definitely have to delete at least one index tuple (or one TID) */
     for (int i = 0; i < delstate->ndeltids; i++)
     {
         TM_IndexStatus *dstatus = delstate->status + delstate->deltids[i].id;
         OffsetNumber idxoffnum = dstatus->idxoffnum;
         ItemId      itemid = PageGetItemId(page, idxoffnum);
         IndexTuple  itup = (IndexTuple) PageGetItem(page, itemid);
         int         nestedi,
                     nitem;
         BTVacuumPosting vacposting;
  
         Assert(OffsetNumberIsValid(idxoffnum));
  
         if (idxoffnum == postingidxoffnum)
         {
             /*
              * This deltid entry is a TID from a posting list tuple that has
              * already been completely processed
              */
             Assert(BTreeTupleIsPosting(itup));
             Assert(ItemPointerCompare(BTreeTupleGetHeapTID(itup),
                                       &delstate->deltids[i].tid) < 0);
             Assert(ItemPointerCompare(BTreeTupleGetMaxHeapTID(itup),
                                       &delstate->deltids[i].tid) >= 0);
             continue;
         }
  
         if (!BTreeTupleIsPosting(itup))
         {
             /* Plain non-pivot tuple */
             Assert(ItemPointerEquals(&itup->t_tid, &delstate->deltids[i].tid));
             if (dstatus->knowndeletable)
                 deletable[ndeletable++] = idxoffnum;
             continue;
         }
  
         /*
          * itup is a posting list tuple whose lowest deltids entry (which may
          * or may not be for the first TID from itup) is considered here now.
          * We should process all of the deltids entries for the posting list
          * together now, though (not just the lowest).  Remember to skip over
          * later itup-related entries during later iterations of outermost
          * loop.
          */
         postingidxoffnum = idxoffnum;   /* Remember work in outermost loop */
         nestedi = i;            /* Initialize for first itup deltids entry */
         vacposting = NULL;      /* Describes final action for itup */
         nitem = BTreeTupleGetNPosting(itup);
         for (int p = 0; p < nitem; p++)
         {
             ItemPointer ptid = BTreeTupleGetPostingN(itup, p);
             int         ptidcmp = -1;
  
             /*
              * This nested loop reuses work across ptid TIDs taken from itup.
              * We take advantage of the fact that both itup's TIDs and deltids
              * entries (within a single itup/posting list grouping) must both
              * be in ascending TID order.
              */
             for (; nestedi < delstate->ndeltids; nestedi++)
             {
                 TM_IndexDelete *tcdeltid = &delstate->deltids[nestedi];
                 TM_IndexStatus *tdstatus = (delstate->status + tcdeltid->id);
  
                 /* Stop once we get past all itup related deltids entries */
                 Assert(tdstatus->idxoffnum >= idxoffnum);
                 if (tdstatus->idxoffnum != idxoffnum)
                     break;
  
                 /* Skip past non-deletable itup related entries up front */
                 if (!tdstatus->knowndeletable)
                     continue;
  
                 /* Entry is first partial ptid match (or an exact match)? */
                 ptidcmp = ItemPointerCompare(&tcdeltid->tid, ptid);
                 if (ptidcmp >= 0)
                 {
                     /* Greater than or equal (partial or exact) match... */
                     break;
                 }
             }
  
             /* ...exact ptid match to a deletable deltids entry? */
             if (ptidcmp != 0)
                 continue;
  
             /* Exact match for deletable deltids entry -- ptid gets deleted */
             if (vacposting == NULL)
             {
                 vacposting = palloc(offsetof(BTVacuumPostingData, deletetids) +
                                     nitem * sizeof(uint16));
                 vacposting->itup = itup;
                 vacposting->updatedoffset = idxoffnum;
                 vacposting->ndeletedtids = 0;
             }
             vacposting->deletetids[vacposting->ndeletedtids++] = p;
         }
  
         /* Final decision on itup, a posting list tuple */
  
         if (vacposting == NULL)
         {
             /* No TIDs to delete from itup -- do nothing */
         }
         else if (vacposting->ndeletedtids == nitem)
         {
             /* Straight delete of itup (to delete all TIDs) */
             deletable[ndeletable++] = idxoffnum;
             /* Turns out we won't need granular information */
             pfree(vacposting);
         }
         else
         {
             /* Delete some (but not all) TIDs from itup */
             Assert(vacposting->ndeletedtids > 0 &&
                    vacposting->ndeletedtids < nitem);
             updatable[nupdatable++] = vacposting;
         }
     }
  
     /* Physically delete tuples (or TIDs) using deletable (or updatable) */
     _bt_delitems_delete(rel, buf, snapshotConflictHorizon,
                         deletable, ndeletable, updatable, nupdatable);
  
     /* be tidy */
     for (int i = 0; i < nupdatable; i++)
         pfree(updatable[i]);
 }

References _bt_delitems_cmp(), _bt_delitems_delete(), Assert(), TM_IndexDeleteOp::bottomup, BTreeTupleGetHeapTID(), BTreeTupleGetMaxHeapTID(), BTreeTupleGetNPosting(), BTreeTupleGetPostingN(), BTreeTupleIsPosting(), buf, BufferGetPage(), BTVacuumPostingData::deletetids, TM_IndexDeleteOp::deltids, i, TM_IndexDelete::id, TM_IndexStatus::idxoffnum, InvalidOffsetNumber, InvalidTransactionId, ItemPointerCompare(), ItemPointerEquals(), BTVacuumPostingData::itup, TM_IndexStatus::knowndeletable, MaxIndexTuplesPerPage, BTVacuumPostingData::ndeletedtids, TM_IndexDeleteOp::ndeltids, OffsetNumberIsValid, PageGetItem(), PageGetItemId(), palloc(), pfree(), qsort, TM_IndexDeleteOp::status, IndexTupleData::t_tid, table_index_delete_tuples(), TM_IndexDelete::tid, BTVacuumPostingData::updatedoffset, and XLogStandbyInfoActive.

Referenced by _bt_bottomupdel_pass(), and _bt_simpledel_pass().

◆ _bt_delitems_update()

static char * _bt_delitems_update	(	BTVacuumPosting *	updatable,
		int	nupdatable,
		OffsetNumber *	updatedoffsets,
		Size *	updatedbuflen,
		bool	needswal
	)

static

Definition at line 1416 of file nbtpage.c.

 {
     char       *updatedbuf = NULL;
     Size        buflen = 0;
  
     /* Shouldn't be called unless there's something to do */
     Assert(nupdatable > 0);
  
     for (int i = 0; i < nupdatable; i++)
     {
         BTVacuumPosting vacposting = updatable[i];
         Size        itemsz;
  
         /* Replace work area IndexTuple with updated version */
         _bt_update_posting(vacposting);
  
         /* Keep track of size of xl_btree_update for updatedbuf in passing */
         itemsz = SizeOfBtreeUpdate + vacposting->ndeletedtids * sizeof(uint16);
         buflen += itemsz;
  
         /* Build updatedoffsets buffer in passing */
         updatedoffsets[i] = vacposting->updatedoffset;
     }
  
     /* XLOG stuff */
     if (needswal)
     {
         Size        offset = 0;
  
         /* Allocate, set final size for caller */
         updatedbuf = palloc(buflen);
         *updatedbuflen = buflen;
         for (int i = 0; i < nupdatable; i++)
         {
             BTVacuumPosting vacposting = updatable[i];
             Size        itemsz;
             xl_btree_update update;
  
             update.ndeletedtids = vacposting->ndeletedtids;
             memcpy(updatedbuf + offset, &update.ndeletedtids,
                    SizeOfBtreeUpdate);
             offset += SizeOfBtreeUpdate;
  
             itemsz = update.ndeletedtids * sizeof(uint16);
             memcpy(updatedbuf + offset, vacposting->deletetids, itemsz);
             offset += itemsz;
         }
     }
  
     return updatedbuf;
 }

References _bt_update_posting(), Assert(), BTVacuumPostingData::deletetids, i, BTVacuumPostingData::ndeletedtids, xl_btree_update::ndeletedtids, palloc(), SizeOfBtreeUpdate, and BTVacuumPostingData::updatedoffset.

Referenced by _bt_delitems_delete(), and _bt_delitems_vacuum().

◆ _bt_delitems_vacuum()

void _bt_delitems_vacuum	(	Relation	rel,
		Buffer	buf,
		OffsetNumber *	deletable,
		int	ndeletable,
		BTVacuumPosting *	updatable,
		int	nupdatable
	)

Definition at line 1166 of file nbtpage.c.

 {
     Page        page = BufferGetPage(buf);
     BTPageOpaque opaque;
     bool        needswal = RelationNeedsWAL(rel);
     char       *updatedbuf = NULL;
     Size        updatedbuflen = 0;
     OffsetNumber updatedoffsets[MaxIndexTuplesPerPage];
  
     /* Shouldn't be called unless there's something to do */
     Assert(ndeletable > 0 || nupdatable > 0);
  
     /* Generate new version of posting lists without deleted TIDs */
     if (nupdatable > 0)
         updatedbuf = _bt_delitems_update(updatable, nupdatable,
                                          updatedoffsets, &updatedbuflen,
                                          needswal);
  
     /* No ereport(ERROR) until changes are logged */
     START_CRIT_SECTION();
  
     /*
      * Handle posting tuple updates.
      *
      * Deliberately do this before handling simple deletes.  If we did it the
      * other way around (i.e. WAL record order -- simple deletes before
      * updates) then we'd have to make compensating changes to the 'updatable'
      * array of offset numbers.
      *
      * PageIndexTupleOverwrite() won't unset each item's LP_DEAD bit when it
      * happens to already be set.  It's important that we not interfere with
      * any future simple index tuple deletion operations.
      */
     for (int i = 0; i < nupdatable; i++)
     {
         OffsetNumber updatedoffset = updatedoffsets[i];
         IndexTuple  itup;
         Size        itemsz;
  
         itup = updatable[i]->itup;
         itemsz = MAXALIGN(IndexTupleSize(itup));
         if (!PageIndexTupleOverwrite(page, updatedoffset, (Item) itup,
                                      itemsz))
             elog(PANIC, "failed to update partially dead item in block %u of index \"%s\"",
                  BufferGetBlockNumber(buf), RelationGetRelationName(rel));
     }
  
     /* Now handle simple deletes of entire tuples */
     if (ndeletable > 0)
         PageIndexMultiDelete(page, deletable, ndeletable);
  
     /*
      * We can clear the vacuum cycle ID since this page has certainly been
      * processed by the current vacuum scan.
      */
     opaque = BTPageGetOpaque(page);
     opaque->btpo_cycleid = 0;
  
     /*
      * Clear the BTP_HAS_GARBAGE page flag.
      *
      * This flag indicates the presence of LP_DEAD items on the page (though
      * not reliably).  Note that we only rely on it with pg_upgrade'd
      * !heapkeyspace indexes.  That's why clearing it here won't usually
      * interfere with simple index tuple deletion.
      */
     opaque->btpo_flags &= ~BTP_HAS_GARBAGE;
  
     MarkBufferDirty(buf);
  
     /* XLOG stuff */
     if (needswal)
     {
         XLogRecPtr  recptr;
         xl_btree_vacuum xlrec_vacuum;
  
         xlrec_vacuum.ndeleted = ndeletable;
         xlrec_vacuum.nupdated = nupdatable;
  
         XLogBeginInsert();
         XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
         XLogRegisterData((char *) &xlrec_vacuum, SizeOfBtreeVacuum);
  
         if (ndeletable > 0)
             XLogRegisterBufData(0, (char *) deletable,
                                 ndeletable * sizeof(OffsetNumber));
  
         if (nupdatable > 0)
         {
             XLogRegisterBufData(0, (char *) updatedoffsets,
                                 nupdatable * sizeof(OffsetNumber));
             XLogRegisterBufData(0, updatedbuf, updatedbuflen);
         }
  
         recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_VACUUM);
  
         PageSetLSN(page, recptr);
     }
  
     END_CRIT_SECTION();
  
     /* can't leak memory here */
     if (updatedbuf != NULL)
         pfree(updatedbuf);
     /* free tuples allocated within _bt_delitems_update() */
     for (int i = 0; i < nupdatable; i++)
         pfree(updatable[i]->itup);
 }

References _bt_delitems_update(), Assert(), BTP_HAS_GARBAGE, BTPageGetOpaque, BTPageOpaqueData::btpo_cycleid, BTPageOpaqueData::btpo_flags, buf, BufferGetBlockNumber(), BufferGetPage(), elog(), END_CRIT_SECTION, i, IndexTupleSize, BTVacuumPostingData::itup, MarkBufferDirty(), MAXALIGN, MaxIndexTuplesPerPage, xl_btree_vacuum::ndeleted, xl_btree_vacuum::nupdated, PageIndexMultiDelete(), PageIndexTupleOverwrite(), PageSetLSN(), PANIC, pfree(), REGBUF_STANDARD, RelationGetRelationName, RelationNeedsWAL, SizeOfBtreeVacuum, START_CRIT_SECTION, XLOG_BTREE_VACUUM, XLogBeginInsert(), XLogInsert(), XLogRegisterBufData(), XLogRegisterBuffer(), and XLogRegisterData().

Referenced by btvacuumpage().

◆ _bt_getbuf()

Buffer _bt_getbuf	(	Relation	rel,
		BlockNumber	blkno,
		int	access
	)

Definition at line 871 of file nbtpage.c.

 {
     Buffer      buf;
  
     if (blkno != P_NEW)
     {
         /* Read an existing block of the relation */
         buf = ReadBuffer(rel, blkno);
         _bt_lockbuf(rel, buf, access);
         _bt_checkpage(rel, buf);
     }
     else
     {
         bool        needLock;
         Page        page;
  
         Assert(access == BT_WRITE);
  
         /*
          * First see if the FSM knows of any free pages.
          *
          * We can't trust the FSM's report unreservedly; we have to check that
          * the page is still free.  (For example, an already-free page could
          * have been re-used between the time the last VACUUM scanned it and
          * the time the VACUUM made its FSM updates.)
          *
          * In fact, it's worse than that: we can't even assume that it's safe
          * to take a lock on the reported page.  If somebody else has a lock
          * on it, or even worse our own caller does, we could deadlock.  (The
          * own-caller scenario is actually not improbable. Consider an index
          * on a serial or timestamp column.  Nearly all splits will be at the
          * rightmost page, so it's entirely likely that _bt_split will call us
          * while holding a lock on the page most recently acquired from FSM. A
          * VACUUM running concurrently with the previous split could well have
          * placed that page back in FSM.)
          *
          * To get around that, we ask for only a conditional lock on the
          * reported page.  If we fail, then someone else is using the page,
          * and we may reasonably assume it's not free.  (If we happen to be
          * wrong, the worst consequence is the page will be lost to use till
          * the next VACUUM, which is no big problem.)
          */
         for (;;)
         {
             blkno = GetFreeIndexPage(rel);
             if (blkno == InvalidBlockNumber)
                 break;
             buf = ReadBuffer(rel, blkno);
             if (_bt_conditionallockbuf(rel, buf))
             {
                 page = BufferGetPage(buf);
  
                 /*
                  * It's possible to find an all-zeroes page in an index.  For
                  * example, a backend might successfully extend the relation
                  * one page and then crash before it is able to make a WAL
                  * entry for adding the page.  If we find a zeroed page then
                  * reclaim it immediately.
                  */
                 if (PageIsNew(page))
                 {
                     /* Okay to use page.  Initialize and return it. */
                     _bt_pageinit(page, BufferGetPageSize(buf));
                     return buf;
                 }
  
                 if (BTPageIsRecyclable(page))
                 {
                     /*
                      * If we are generating WAL for Hot Standby then create a
                      * WAL record that will allow us to conflict with queries
                      * running on standby, in case they have snapshots older
                      * than safexid value
                      */
                     if (XLogStandbyInfoActive() && RelationNeedsWAL(rel))
                         _bt_log_reuse_page(rel, blkno,
                                            BTPageGetDeleteXid(page));
  
                     /* Okay to use page.  Re-initialize and return it. */
                     _bt_pageinit(page, BufferGetPageSize(buf));
                     return buf;
                 }
                 elog(DEBUG2, "FSM returned nonrecyclable page");
                 _bt_relbuf(rel, buf);
             }
             else
             {
                 elog(DEBUG2, "FSM returned nonlockable page");
                 /* couldn't get lock, so just drop pin */
                 ReleaseBuffer(buf);
             }
         }
  
         /*
          * Extend the relation by one page.
          *
          * We have to use a lock to ensure no one else is extending the rel at
          * the same time, else we will both try to initialize the same new
          * page.  We can skip locking for new or temp relations, however,
          * since no one else could be accessing them.
          */
         needLock = !RELATION_IS_LOCAL(rel);
  
         if (needLock)
             LockRelationForExtension(rel, ExclusiveLock);
  
         buf = ReadBuffer(rel, P_NEW);
  
         /* Acquire buffer lock on new page */
         _bt_lockbuf(rel, buf, BT_WRITE);
  
         /*
          * Release the file-extension lock; it's now OK for someone else to
          * extend the relation some more.  Note that we cannot release this
          * lock before we have buffer lock on the new page, or we risk a race
          * condition against btvacuumscan --- see comments therein.
          */
         if (needLock)
             UnlockRelationForExtension(rel, ExclusiveLock);
  
         /* Initialize the new page before returning it */
         page = BufferGetPage(buf);
         Assert(PageIsNew(page));
         _bt_pageinit(page, BufferGetPageSize(buf));
     }
  
     /* ref count and lock type are correct */
     return buf;
 }

References _bt_checkpage(), _bt_conditionallockbuf(), _bt_lockbuf(), _bt_log_reuse_page(), _bt_pageinit(), _bt_relbuf(), Assert(), BT_WRITE, BTPageGetDeleteXid(), BTPageIsRecyclable(), buf, BufferGetPage(), BufferGetPageSize(), DEBUG2, elog(), ExclusiveLock, GetFreeIndexPage(), InvalidBlockNumber, LockRelationForExtension(), P_NEW, PageIsNew(), ReadBuffer(), RELATION_IS_LOCAL, RelationNeedsWAL, ReleaseBuffer(), UnlockRelationForExtension(), and XLogStandbyInfoActive.

Referenced by _bt_finish_split(), _bt_getroot(), _bt_getrootheight(), _bt_getstackbuf(), _bt_gettrueroot(), _bt_insertonpg(), _bt_killitems(), _bt_leftsib_splitflag(), _bt_metaversion(), _bt_moveright(), _bt_newroot(), _bt_pagedel(), _bt_readnextpage(), _bt_rightsib_halfdeadflag(), _bt_set_cleanup_info(), _bt_split(), _bt_unlink_halfdead_page(), _bt_vacuum_needs_cleanup(), and _bt_walk_left().

◆ _bt_getmeta()

static BTMetaPageData * _bt_getmeta	(	Relation	rel,
		Buffer	metabuf
	)

static

Definition at line 144 of file nbtpage.c.

 {
     Page        metapg;
     BTPageOpaque metaopaque;
     BTMetaPageData *metad;
  
     metapg = BufferGetPage(metabuf);
     metaopaque = BTPageGetOpaque(metapg);
     metad = BTPageGetMeta(metapg);
  
     /* sanity-check the metapage */
     if (!P_ISMETA(metaopaque) ||
         metad->btm_magic != BTREE_MAGIC)
         ereport(ERROR,
                 (errcode(ERRCODE_INDEX_CORRUPTED),
                  errmsg("index \"%s\" is not a btree",
                         RelationGetRelationName(rel))));
  
     if (metad->btm_version < BTREE_MIN_VERSION ||
         metad->btm_version > BTREE_VERSION)
         ereport(ERROR,
                 (errcode(ERRCODE_INDEX_CORRUPTED),
                  errmsg("version mismatch in index \"%s\": file version %d, "
                         "current version %d, minimal supported version %d",
                         RelationGetRelationName(rel),
                         metad->btm_version, BTREE_VERSION, BTREE_MIN_VERSION)));
  
     return metad;
 }

References BTMetaPageData::btm_magic, BTMetaPageData::btm_version, BTPageGetMeta, BTPageGetOpaque, BTREE_MAGIC, BTREE_MIN_VERSION, BTREE_VERSION, BufferGetPage(), ereport, errcode(), errmsg(), ERROR, P_ISMETA, and RelationGetRelationName.

Referenced by _bt_getroot(), _bt_getrootheight(), and _bt_metaversion().

◆ _bt_getroot()

Buffer _bt_getroot	(	Relation	rel,
		int	access
	)

Definition at line 343 of file nbtpage.c.

 {
     Buffer      metabuf;
     Buffer      rootbuf;
     Page        rootpage;
     BTPageOpaque rootopaque;
     BlockNumber rootblkno;
     uint32      rootlevel;
     BTMetaPageData *metad;
  
     /*
      * Try to use previously-cached metapage data to find the root.  This
      * normally saves one buffer access per index search, which is a very
      * helpful savings in bufmgr traffic and hence contention.
      */
     if (rel->rd_amcache != NULL)
     {
         metad = (BTMetaPageData *) rel->rd_amcache;
         /* We shouldn't have cached it if any of these fail */
         Assert(metad->btm_magic == BTREE_MAGIC);
         Assert(metad->btm_version >= BTREE_MIN_VERSION);
         Assert(metad->btm_version <= BTREE_VERSION);
         Assert(!metad->btm_allequalimage ||
                metad->btm_version > BTREE_NOVAC_VERSION);
         Assert(metad->btm_root != P_NONE);
  
         rootblkno = metad->btm_fastroot;
         Assert(rootblkno != P_NONE);
         rootlevel = metad->btm_fastlevel;
  
         rootbuf = _bt_getbuf(rel, rootblkno, BT_READ);
         rootpage = BufferGetPage(rootbuf);
         rootopaque = BTPageGetOpaque(rootpage);
  
         /*
          * Since the cache might be stale, we check the page more carefully
          * here than normal.  We *must* check that it's not deleted. If it's
          * not alone on its level, then we reject too --- this may be overly
          * paranoid but better safe than sorry.  Note we don't check P_ISROOT,
          * because that's not set in a "fast root".
          */
         if (!P_IGNORE(rootopaque) &&
             rootopaque->btpo_level == rootlevel &&
             P_LEFTMOST(rootopaque) &&
             P_RIGHTMOST(rootopaque))
         {
             /* OK, accept cached page as the root */
             return rootbuf;
         }
         _bt_relbuf(rel, rootbuf);
         /* Cache is stale, throw it away */
         if (rel->rd_amcache)
             pfree(rel->rd_amcache);
         rel->rd_amcache = NULL;
     }
  
     metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
     metad = _bt_getmeta(rel, metabuf);
  
     /* if no root page initialized yet, do it */
     if (metad->btm_root == P_NONE)
     {
         Page        metapg;
  
         /* If access = BT_READ, caller doesn't want us to create root yet */
         if (access == BT_READ)
         {
             _bt_relbuf(rel, metabuf);
             return InvalidBuffer;
         }
  
         /* trade in our read lock for a write lock */
         _bt_unlockbuf(rel, metabuf);
         _bt_lockbuf(rel, metabuf, BT_WRITE);
  
         /*
          * Race condition:  if someone else initialized the metadata between
          * the time we released the read lock and acquired the write lock, we
          * must avoid doing it again.
          */
         if (metad->btm_root != P_NONE)
         {
             /*
              * Metadata initialized by someone else.  In order to guarantee no
              * deadlocks, we have to release the metadata page and start all
              * over again.  (Is that really true? But it's hardly worth trying
              * to optimize this case.)
              */
             _bt_relbuf(rel, metabuf);
             return _bt_getroot(rel, access);
         }
  
         /*
          * Get, initialize, write, and leave a lock of the appropriate type on
          * the new root page.  Since this is the first page in the tree, it's
          * a leaf as well as the root.
          */
         rootbuf = _bt_getbuf(rel, P_NEW, BT_WRITE);
         rootblkno = BufferGetBlockNumber(rootbuf);
         rootpage = BufferGetPage(rootbuf);
         rootopaque = BTPageGetOpaque(rootpage);
         rootopaque->btpo_prev = rootopaque->btpo_next = P_NONE;
         rootopaque->btpo_flags = (BTP_LEAF | BTP_ROOT);
         rootopaque->btpo_level = 0;
         rootopaque->btpo_cycleid = 0;
         /* Get raw page pointer for metapage */
         metapg = BufferGetPage(metabuf);
  
         /* NO ELOG(ERROR) till meta is updated */
         START_CRIT_SECTION();
  
         /* upgrade metapage if needed */
         if (metad->btm_version < BTREE_NOVAC_VERSION)
             _bt_upgrademetapage(metapg);
  
         metad->btm_root = rootblkno;
         metad->btm_level = 0;
         metad->btm_fastroot = rootblkno;
         metad->btm_fastlevel = 0;
         metad->btm_last_cleanup_num_delpages = 0;
         metad->btm_last_cleanup_num_heap_tuples = -1.0;
  
         MarkBufferDirty(rootbuf);
         MarkBufferDirty(metabuf);
  
         /* XLOG stuff */
         if (RelationNeedsWAL(rel))
         {
             xl_btree_newroot xlrec;
             XLogRecPtr  recptr;
             xl_btree_metadata md;
  
             XLogBeginInsert();
             XLogRegisterBuffer(0, rootbuf, REGBUF_WILL_INIT);
             XLogRegisterBuffer(2, metabuf, REGBUF_WILL_INIT | REGBUF_STANDARD);
  
             Assert(metad->btm_version >= BTREE_NOVAC_VERSION);
             md.version = metad->btm_version;
             md.root = rootblkno;
             md.level = 0;
             md.fastroot = rootblkno;
             md.fastlevel = 0;
             md.last_cleanup_num_delpages = 0;
             md.allequalimage = metad->btm_allequalimage;
  
             XLogRegisterBufData(2, (char *) &md, sizeof(xl_btree_metadata));
  
             xlrec.rootblk = rootblkno;
             xlrec.level = 0;
  
             XLogRegisterData((char *) &xlrec, SizeOfBtreeNewroot);
  
             recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_NEWROOT);
  
             PageSetLSN(rootpage, recptr);
             PageSetLSN(metapg, recptr);
         }
  
         END_CRIT_SECTION();
  
         /*
          * swap root write lock for read lock.  There is no danger of anyone
          * else accessing the new root page while it's unlocked, since no one
          * else knows where it is yet.
          */
         _bt_unlockbuf(rel, rootbuf);
         _bt_lockbuf(rel, rootbuf, BT_READ);
  
         /* okay, metadata is correct, release lock on it without caching */
         _bt_relbuf(rel, metabuf);
     }
     else
     {
         rootblkno = metad->btm_fastroot;
         Assert(rootblkno != P_NONE);
         rootlevel = metad->btm_fastlevel;
  
         /*
          * Cache the metapage data for next time
          */
         rel->rd_amcache = MemoryContextAlloc(rel->rd_indexcxt,
                                              sizeof(BTMetaPageData));
         memcpy(rel->rd_amcache, metad, sizeof(BTMetaPageData));
  
         /*
          * We are done with the metapage; arrange to release it via first
          * _bt_relandgetbuf call
          */
         rootbuf = metabuf;
  
         for (;;)
         {
             rootbuf = _bt_relandgetbuf(rel, rootbuf, rootblkno, BT_READ);
             rootpage = BufferGetPage(rootbuf);
             rootopaque = BTPageGetOpaque(rootpage);
  
             if (!P_IGNORE(rootopaque))
                 break;
  
             /* it's dead, Jim.  step right one page */
             if (P_RIGHTMOST(rootopaque))
                 elog(ERROR, "no live root page found in index \"%s\"",
                      RelationGetRelationName(rel));
             rootblkno = rootopaque->btpo_next;
         }
  
         if (rootopaque->btpo_level != rootlevel)
             elog(ERROR, "root page %u of index \"%s\" has level %u, expected %u",
                  rootblkno, RelationGetRelationName(rel),
                  rootopaque->btpo_level, rootlevel);
     }
  
     /*
      * By here, we have a pin and read lock on the root page, and no lock set
      * on the metadata page.  Return the root page's buffer.
      */
     return rootbuf;
 }

Referenced by _bt_get_endpoint(), and _bt_search().

◆ _bt_getrootheight()

int _bt_getrootheight ( Relation rel )

Definition at line 672 of file nbtpage.c.

 {
     BTMetaPageData *metad;
  
     if (rel->rd_amcache == NULL)
     {
         Buffer      metabuf;
  
         metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
         metad = _bt_getmeta(rel, metabuf);
  
         /*
          * If there's no root page yet, _bt_getroot() doesn't expect a cache
          * to be made, so just stop here and report the index height is zero.
          * (XXX perhaps _bt_getroot() should be changed to allow this case.)
          */
         if (metad->btm_root == P_NONE)
         {
             _bt_relbuf(rel, metabuf);
             return 0;
         }
  
         /*
          * Cache the metapage data for next time
          */
         rel->rd_amcache = MemoryContextAlloc(rel->rd_indexcxt,
                                              sizeof(BTMetaPageData));
         memcpy(rel->rd_amcache, metad, sizeof(BTMetaPageData));
         _bt_relbuf(rel, metabuf);
     }
  
     /* Get cached page */
     metad = (BTMetaPageData *) rel->rd_amcache;
     /* We shouldn't have cached it if any of these fail */
     Assert(metad->btm_magic == BTREE_MAGIC);
     Assert(metad->btm_version >= BTREE_MIN_VERSION);
     Assert(metad->btm_version <= BTREE_VERSION);
     Assert(!metad->btm_allequalimage ||
            metad->btm_version > BTREE_NOVAC_VERSION);
     Assert(metad->btm_fastroot != P_NONE);
  
     return metad->btm_fastlevel;
 }

References _bt_getbuf(), _bt_getmeta(), _bt_relbuf(), Assert(), BT_READ, BTMetaPageData::btm_allequalimage, BTMetaPageData::btm_fastlevel, BTMetaPageData::btm_fastroot, BTMetaPageData::btm_magic, BTMetaPageData::btm_root, BTMetaPageData::btm_version, BTREE_MAGIC, BTREE_METAPAGE, BTREE_MIN_VERSION, BTREE_NOVAC_VERSION, BTREE_VERSION, MemoryContextAlloc(), P_NONE, RelationData::rd_amcache, and RelationData::rd_indexcxt.

Referenced by _bt_insertonpg(), and get_relation_info().

◆ _bt_gettrueroot()

Buffer _bt_gettrueroot ( Relation rel )

Definition at line 577 of file nbtpage.c.

 {
     Buffer      metabuf;
     Page        metapg;
     BTPageOpaque metaopaque;
     Buffer      rootbuf;
     Page        rootpage;
     BTPageOpaque rootopaque;
     BlockNumber rootblkno;
     uint32      rootlevel;
     BTMetaPageData *metad;
  
     /*
      * We don't try to use cached metapage data here, since (a) this path is
      * not performance-critical, and (b) if we are here it suggests our cache
      * is out-of-date anyway.  In light of point (b), it's probably safest to
      * actively flush any cached metapage info.
      */
     if (rel->rd_amcache)
         pfree(rel->rd_amcache);
     rel->rd_amcache = NULL;
  
     metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
     metapg = BufferGetPage(metabuf);
     metaopaque = BTPageGetOpaque(metapg);
     metad = BTPageGetMeta(metapg);
  
     if (!P_ISMETA(metaopaque) ||
         metad->btm_magic != BTREE_MAGIC)
         ereport(ERROR,
                 (errcode(ERRCODE_INDEX_CORRUPTED),
                  errmsg("index \"%s\" is not a btree",
                         RelationGetRelationName(rel))));
  
     if (metad->btm_version < BTREE_MIN_VERSION ||
         metad->btm_version > BTREE_VERSION)
         ereport(ERROR,
                 (errcode(ERRCODE_INDEX_CORRUPTED),
                  errmsg("version mismatch in index \"%s\": file version %d, "
                         "current version %d, minimal supported version %d",
                         RelationGetRelationName(rel),
                         metad->btm_version, BTREE_VERSION, BTREE_MIN_VERSION)));
  
     /* if no root page initialized yet, fail */
     if (metad->btm_root == P_NONE)
     {
         _bt_relbuf(rel, metabuf);
         return InvalidBuffer;
     }
  
     rootblkno = metad->btm_root;
     rootlevel = metad->btm_level;
  
     /*
      * We are done with the metapage; arrange to release it via first
      * _bt_relandgetbuf call
      */
     rootbuf = metabuf;
  
     for (;;)
     {
         rootbuf = _bt_relandgetbuf(rel, rootbuf, rootblkno, BT_READ);
         rootpage = BufferGetPage(rootbuf);
         rootopaque = BTPageGetOpaque(rootpage);
  
         if (!P_IGNORE(rootopaque))
             break;
  
         /* it's dead, Jim.  step right one page */
         if (P_RIGHTMOST(rootopaque))
             elog(ERROR, "no live root page found in index \"%s\"",
                  RelationGetRelationName(rel));
         rootblkno = rootopaque->btpo_next;
     }
  
     if (rootopaque->btpo_level != rootlevel)
         elog(ERROR, "root page %u of index \"%s\" has level %u, expected %u",
              rootblkno, RelationGetRelationName(rel),
              rootopaque->btpo_level, rootlevel);
  
     return rootbuf;
 }

References _bt_getbuf(), _bt_relandgetbuf(), _bt_relbuf(), BT_READ, BTMetaPageData::btm_level, BTMetaPageData::btm_magic, BTMetaPageData::btm_root, BTMetaPageData::btm_version, BTPageGetMeta, BTPageGetOpaque, BTPageOpaqueData::btpo_level, BTPageOpaqueData::btpo_next, BTREE_MAGIC, BTREE_METAPAGE, BTREE_MIN_VERSION, BTREE_VERSION, BufferGetPage(), elog(), ereport, errcode(), errmsg(), ERROR, InvalidBuffer, P_IGNORE, P_ISMETA, P_NONE, P_RIGHTMOST, pfree(), RelationData::rd_amcache, and RelationGetRelationName.

Referenced by _bt_get_endpoint().

◆ _bt_initmetapage()

void _bt_initmetapage	(	Page	page,
		BlockNumber	rootbknum,
		uint32	level,
		bool	allequalimage
	)

Definition at line 69 of file nbtpage.c.

 {
     BTMetaPageData *metad;
     BTPageOpaque metaopaque;
  
     _bt_pageinit(page, BLCKSZ);
  
     metad = BTPageGetMeta(page);
     metad->btm_magic = BTREE_MAGIC;
     metad->btm_version = BTREE_VERSION;
     metad->btm_root = rootbknum;
     metad->btm_level = level;
     metad->btm_fastroot = rootbknum;
     metad->btm_fastlevel = level;
     metad->btm_last_cleanup_num_delpages = 0;
     metad->btm_last_cleanup_num_heap_tuples = -1.0;
     metad->btm_allequalimage = allequalimage;
  
     metaopaque = BTPageGetOpaque(page);
     metaopaque->btpo_flags = BTP_META;
  
     /*
      * Set pd_lower just past the end of the metadata.  This is essential,
      * because without doing so, metadata will be lost if xlog.c compresses
      * the page.
      */
     ((PageHeader) page)->pd_lower =
         ((char *) metad + sizeof(BTMetaPageData)) - (char *) page;
 }

References _bt_pageinit(), BTMetaPageData::btm_allequalimage, BTMetaPageData::btm_fastlevel, BTMetaPageData::btm_fastroot, BTMetaPageData::btm_last_cleanup_num_delpages, BTMetaPageData::btm_last_cleanup_num_heap_tuples, BTMetaPageData::btm_level, BTMetaPageData::btm_magic, BTMetaPageData::btm_root, BTMetaPageData::btm_version, BTP_META, BTPageGetMeta, BTPageGetOpaque, BTPageOpaqueData::btpo_flags, BTREE_MAGIC, and BTREE_VERSION.

Referenced by _bt_uppershutdown(), and btbuildempty().

◆ _bt_leftsib_splitflag()

static bool _bt_leftsib_splitflag	(	Relation	rel,
		BlockNumber	leftsib,
		BlockNumber	target
	)

static

Definition at line 1709 of file nbtpage.c.

 {
     Buffer      buf;
     Page        page;
     BTPageOpaque opaque;
     bool        result;
  
     /* Easy case: No left sibling */
     if (leftsib == P_NONE)
         return false;
  
     buf = _bt_getbuf(rel, leftsib, BT_READ);
     page = BufferGetPage(buf);
     opaque = BTPageGetOpaque(page);
  
     /*
      * If the left sibling was concurrently split, so that its next-pointer
      * doesn't point to the current page anymore, the split that created
      * target must be completed.  Caller can reasonably expect that there will
      * be a downlink to the target page that it can relocate using its stack.
      * (We don't allow splitting an incompletely split page again until the
      * previous split has been completed.)
      */
     result = (opaque->btpo_next == target && P_INCOMPLETE_SPLIT(opaque));
     _bt_relbuf(rel, buf);
  
     return result;
 }

References _bt_getbuf(), _bt_relbuf(), BT_READ, BTPageGetOpaque, BTPageOpaqueData::btpo_next, buf, BufferGetPage(), P_INCOMPLETE_SPLIT, and P_NONE.

Referenced by _bt_lock_subtree_parent(), and _bt_pagedel().

◆ _bt_lock_subtree_parent()

static bool _bt_lock_subtree_parent	(	Relation	rel,
		BlockNumber	child,
		BTStack	stack,
		Buffer *	subtreeparent,
		OffsetNumber *	poffset,
		BlockNumber *	topparent,
		BlockNumber *	topparentrightsib
	)

static

Definition at line 2776 of file nbtpage.c.

 {
     BlockNumber parent,
                 leftsibparent;
     OffsetNumber parentoffset,
                 maxoff;
     Buffer      pbuf;
     Page        page;
     BTPageOpaque opaque;
  
     /*
      * Locate the pivot tuple whose downlink points to "child".  Write lock
      * the parent page itself.
      */
     pbuf = _bt_getstackbuf(rel, stack, child);
     if (pbuf == InvalidBuffer)
     {
         /*
          * Failed to "re-find" a pivot tuple whose downlink matched our child
          * block number on the parent level -- the index must be corrupt.
          * Don't even try to delete the leafbuf subtree.  Just report the
          * issue and press on with vacuuming the index.
          *
          * Note: _bt_getstackbuf() recovers from concurrent page splits that
          * take place on the parent level.  Its approach is a near-exhaustive
          * linear search.  This also gives it a surprisingly good chance of
          * recovering in the event of a buggy or inconsistent opclass.  But we
          * don't rely on that here.
          */
         ereport(LOG,
                 (errcode(ERRCODE_INDEX_CORRUPTED),
                  errmsg_internal("failed to re-find parent key in index \"%s\" for deletion target page %u",
                                  RelationGetRelationName(rel), child)));
         return false;
     }
  
     parent = stack->bts_blkno;
     parentoffset = stack->bts_offset;
  
     page = BufferGetPage(pbuf);
     opaque = BTPageGetOpaque(page);
     maxoff = PageGetMaxOffsetNumber(page);
     leftsibparent = opaque->btpo_prev;
  
     /*
      * _bt_getstackbuf() completes page splits on returned parent buffer when
      * required.
      *
      * In general it's a bad idea for VACUUM to use up more disk space, which
      * is why page deletion does not finish incomplete page splits most of the
      * time.  We allow this limited exception because the risk is much lower,
      * and the potential downside of not proceeding is much higher:  A single
      * internal page with the INCOMPLETE_SPLIT flag set might otherwise
      * prevent us from deleting hundreds of empty leaf pages from one level
      * down.
      */
     Assert(!P_INCOMPLETE_SPLIT(opaque));
  
     if (parentoffset < maxoff)
     {
         /*
          * Child is not the rightmost child in parent, so it's safe to delete
          * the subtree whose root/topparent is child page
          */
         *subtreeparent = pbuf;
         *poffset = parentoffset;
         return true;
     }
  
     /*
      * Child is the rightmost child of parent.
      *
      * Since it's the rightmost child of parent, deleting the child (or
      * deleting the subtree whose root/topparent is the child page) is only
      * safe when it's also possible to delete the parent.
      */
     Assert(parentoffset == maxoff);
     if (parentoffset != P_FIRSTDATAKEY(opaque) || P_RIGHTMOST(opaque))
     {
         /*
          * Child isn't parent's only child, or parent is rightmost on its
          * entire level.  Definitely cannot delete any pages.
          */
         _bt_relbuf(rel, pbuf);
         return false;
     }
  
     /*
      * Now make sure that the parent deletion is itself safe by examining the
      * child's grandparent page.  Recurse, passing the parent page as the
      * child page (child's grandparent is the parent on the next level up). If
      * parent deletion is unsafe, then child deletion must also be unsafe (in
      * which case caller cannot delete any pages at all).
      */
     *topparent = parent;
     *topparentrightsib = opaque->btpo_next;
  
     /*
      * Release lock on parent before recursing.
      *
      * It's OK to release page locks on parent before recursive call locks
      * grandparent.  An internal page can only acquire an entry if the child
      * is split, but that cannot happen as long as we still hold a lock on the
      * leafbuf page.
      */
     _bt_relbuf(rel, pbuf);
  
     /*
      * Before recursing, check that the left sibling of parent (if any) is not
      * marked with INCOMPLETE_SPLIT flag first (must do so after we drop the
      * parent lock).
      *
      * Note: We deliberately avoid completing incomplete splits here.
      */
     if (_bt_leftsib_splitflag(rel, leftsibparent, parent))
         return false;
  
     /* Recurse to examine child page's grandparent page */
     return _bt_lock_subtree_parent(rel, parent, stack->bts_parent,
                                    subtreeparent, poffset,
                                    topparent, topparentrightsib);
 }

References _bt_getstackbuf(), _bt_leftsib_splitflag(), _bt_relbuf(), Assert(), BTPageGetOpaque, BTPageOpaqueData::btpo_next, BTPageOpaqueData::btpo_prev, BTStackData::bts_blkno, BTStackData::bts_offset, BTStackData::bts_parent, BufferGetPage(), ereport, errcode(), errmsg_internal(), InvalidBuffer, LOG, P_FIRSTDATAKEY, P_INCOMPLETE_SPLIT, P_RIGHTMOST, PageGetMaxOffsetNumber(), and RelationGetRelationName.

Referenced by _bt_mark_page_halfdead().

◆ _bt_lockbuf()

void _bt_lockbuf	(	Relation	rel,
		Buffer	buf,
		int	access
	)

Definition at line 1051 of file nbtpage.c.

 {
     /* LockBuffer() asserts that pin is held by this backend */
     LockBuffer(buf, access);
  
     /*
      * It doesn't matter that _bt_unlockbuf() won't get called in the event of
      * an nbtree error (e.g. a unique violation error).  That won't cause
      * Valgrind false positives.
      *
      * The nbtree client requests are superimposed on top of the bufmgr.c
      * buffer pin client requests.  In the event of an nbtree error the buffer
      * will certainly get marked as defined when the backend once again
      * acquires its first pin on the buffer. (Of course, if the backend never
      * touches the buffer again then it doesn't matter that it remains
      * non-accessible to Valgrind.)
      *
      * Note: When an IndexTuple C pointer gets computed using an ItemId read
      * from a page while a lock was held, the C pointer becomes unsafe to
      * dereference forever as soon as the lock is released.  Valgrind can only
      * detect cases where the pointer gets dereferenced with no _current_
      * lock/pin held, though.
      */
     if (!RelationUsesLocalBuffers(rel))
         VALGRIND_MAKE_MEM_DEFINED(BufferGetPage(buf), BLCKSZ);
 }

References buf, BufferGetPage(), LockBuffer(), RelationUsesLocalBuffers, and VALGRIND_MAKE_MEM_DEFINED.

Referenced by _bt_getbuf(), _bt_getroot(), _bt_killitems(), _bt_moveright(), _bt_pagedel(), _bt_readnextpage(), _bt_relandgetbuf(), _bt_search(), _bt_set_cleanup_info(), _bt_unlink_halfdead_page(), and btvacuumpage().

◆ _bt_log_reuse_page()

static void _bt_log_reuse_page	(	Relation	rel,
		BlockNumber	blkno,
		FullTransactionId	safexid
	)

static

Definition at line 828 of file nbtpage.c.

 {
     xl_btree_reuse_page xlrec_reuse;
  
     /*
      * Note that we don't register the buffer with the record, because this
      * operation doesn't modify the page. This record only exists to provide a
      * conflict point for Hot Standby.
      */
  
     /* XLOG stuff */
     xlrec_reuse.locator = rel->rd_locator;
     xlrec_reuse.block = blkno;
     xlrec_reuse.snapshotConflictHorizon = safexid;
  
     XLogBeginInsert();
     XLogRegisterData((char *) &xlrec_reuse, SizeOfBtreeReusePage);
  
     XLogInsert(RM_BTREE_ID, XLOG_BTREE_REUSE_PAGE);
 }

References xl_btree_reuse_page::block, xl_btree_reuse_page::locator, RelationData::rd_locator, SizeOfBtreeReusePage, xl_btree_reuse_page::snapshotConflictHorizon, XLOG_BTREE_REUSE_PAGE, XLogBeginInsert(), XLogInsert(), and XLogRegisterData().

Referenced by _bt_getbuf().

◆ _bt_mark_page_halfdead()

static bool _bt_mark_page_halfdead	(	Relation	rel,
		Buffer	leafbuf,
		BTStack	stack
	)

static

Definition at line 2087 of file nbtpage.c.

 {
     BlockNumber leafblkno;
     BlockNumber leafrightsib;
     BlockNumber topparent;
     BlockNumber topparentrightsib;
     ItemId      itemid;
     Page        page;
     BTPageOpaque opaque;
     Buffer      subtreeparent;
     OffsetNumber poffset;
     OffsetNumber nextoffset;
     IndexTuple  itup;
     IndexTupleData trunctuple;
  
     page = BufferGetPage(leafbuf);
     opaque = BTPageGetOpaque(page);
  
     Assert(!P_RIGHTMOST(opaque) && !P_ISROOT(opaque) &&
            P_ISLEAF(opaque) && !P_IGNORE(opaque) &&
            P_FIRSTDATAKEY(opaque) > PageGetMaxOffsetNumber(page));
  
     /*
      * Save info about the leaf page.
      */
     leafblkno = BufferGetBlockNumber(leafbuf);
     leafrightsib = opaque->btpo_next;
  
     /*
      * Before attempting to lock the parent page, check that the right sibling
      * is not in half-dead state.  A half-dead right sibling would have no
      * downlink in the parent, which would be highly confusing later when we
      * delete the downlink.  It would fail the "right sibling of target page
      * is also the next child in parent page" cross-check below.
      */
     if (_bt_rightsib_halfdeadflag(rel, leafrightsib))
     {
         elog(DEBUG1, "could not delete page %u because its right sibling %u is half-dead",
              leafblkno, leafrightsib);
         return false;
     }
  
     /*
      * We cannot delete a page that is the rightmost child of its immediate
      * parent, unless it is the only child --- in which case the parent has to
      * be deleted too, and the same condition applies recursively to it. We
      * have to check this condition all the way up before trying to delete,
      * and lock the parent of the root of the to-be-deleted subtree (the
      * "subtree parent").  _bt_lock_subtree_parent() locks the subtree parent
      * for us.  We remove the downlink to the "top parent" page (subtree root
      * page) from the subtree parent page below.
      *
      * Initialize topparent to be leafbuf page now.  The final to-be-deleted
      * subtree is often a degenerate one page subtree consisting only of the
      * leafbuf page.  When that happens, the leafbuf page is the final subtree
      * root page/top parent page.
      */
     topparent = leafblkno;
     topparentrightsib = leafrightsib;
     if (!_bt_lock_subtree_parent(rel, leafblkno, stack,
                                  &subtreeparent, &poffset,
                                  &topparent, &topparentrightsib))
         return false;
  
     /*
      * Check that the parent-page index items we're about to delete/overwrite
      * in subtree parent page contain what we expect.  This can fail if the
      * index has become corrupt for some reason.  We want to throw any error
      * before entering the critical section --- otherwise it'd be a PANIC.
      */
     page = BufferGetPage(subtreeparent);
     opaque = BTPageGetOpaque(page);
  
 #ifdef USE_ASSERT_CHECKING
  
     /*
      * This is just an assertion because _bt_lock_subtree_parent should have
      * guaranteed tuple has the expected contents
      */
     itemid = PageGetItemId(page, poffset);
     itup = (IndexTuple) PageGetItem(page, itemid);
     Assert(BTreeTupleGetDownLink(itup) == topparent);
 #endif
  
     nextoffset = OffsetNumberNext(poffset);
     itemid = PageGetItemId(page, nextoffset);
     itup = (IndexTuple) PageGetItem(page, itemid);
     if (BTreeTupleGetDownLink(itup) != topparentrightsib)
         ereport(ERROR,
                 (errcode(ERRCODE_INDEX_CORRUPTED),
                  errmsg_internal("right sibling %u of block %u is not next child %u of block %u in index \"%s\"",
                                  topparentrightsib, topparent,
                                  BTreeTupleGetDownLink(itup),
                                  BufferGetBlockNumber(subtreeparent),
                                  RelationGetRelationName(rel))));
  
     /*
      * Any insert which would have gone on the leaf block will now go to its
      * right sibling.  In other words, the key space moves right.
      */
     PredicateLockPageCombine(rel, leafblkno, leafrightsib);
  
     /* No ereport(ERROR) until changes are logged */
     START_CRIT_SECTION();
  
     /*
      * Update parent of subtree.  We want to delete the downlink to the top
      * parent page/root of the subtree, and the *following* key.  Easiest way
      * is to copy the right sibling's downlink over the downlink that points
      * to top parent page, and then delete the right sibling's original pivot
      * tuple.
      *
      * Lanin and Shasha make the key space move left when deleting a page,
      * whereas the key space moves right here.  That's why we cannot simply
      * delete the pivot tuple with the downlink to the top parent page.  See
      * nbtree/README.
      */
     page = BufferGetPage(subtreeparent);
     opaque = BTPageGetOpaque(page);
  
     itemid = PageGetItemId(page, poffset);
     itup = (IndexTuple) PageGetItem(page, itemid);
     BTreeTupleSetDownLink(itup, topparentrightsib);
  
     nextoffset = OffsetNumberNext(poffset);
     PageIndexTupleDelete(page, nextoffset);
  
     /*
      * Mark the leaf page as half-dead, and stamp it with a link to the top
      * parent page.  When the leaf page is also the top parent page, the link
      * is set to InvalidBlockNumber.
      */
     page = BufferGetPage(leafbuf);
     opaque = BTPageGetOpaque(page);
     opaque->btpo_flags |= BTP_HALF_DEAD;
  
     Assert(PageGetMaxOffsetNumber(page) == P_HIKEY);
     MemSet(&trunctuple, 0, sizeof(IndexTupleData));
     trunctuple.t_info = sizeof(IndexTupleData);
     if (topparent != leafblkno)
         BTreeTupleSetTopParent(&trunctuple, topparent);
     else
         BTreeTupleSetTopParent(&trunctuple, InvalidBlockNumber);
  
     if (!PageIndexTupleOverwrite(page, P_HIKEY, (Item) &trunctuple,
                                  IndexTupleSize(&trunctuple)))
         elog(ERROR, "could not overwrite high key in half-dead page");
  
     /* Must mark buffers dirty before XLogInsert */
     MarkBufferDirty(subtreeparent);
     MarkBufferDirty(leafbuf);
  
     /* XLOG stuff */
     if (RelationNeedsWAL(rel))
     {
         xl_btree_mark_page_halfdead xlrec;
         XLogRecPtr  recptr;
  
         xlrec.poffset = poffset;
         xlrec.leafblk = leafblkno;
         if (topparent != leafblkno)
             xlrec.topparent = topparent;
         else
             xlrec.topparent = InvalidBlockNumber;
  
         XLogBeginInsert();
         XLogRegisterBuffer(0, leafbuf, REGBUF_WILL_INIT);
         XLogRegisterBuffer(1, subtreeparent, REGBUF_STANDARD);
  
         page = BufferGetPage(leafbuf);
         opaque = BTPageGetOpaque(page);
         xlrec.leftblk = opaque->btpo_prev;
         xlrec.rightblk = opaque->btpo_next;
  
         XLogRegisterData((char *) &xlrec, SizeOfBtreeMarkPageHalfDead);
  
         recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_MARK_PAGE_HALFDEAD);
  
         page = BufferGetPage(subtreeparent);
         PageSetLSN(page, recptr);
         page = BufferGetPage(leafbuf);
         PageSetLSN(page, recptr);
     }
  
     END_CRIT_SECTION();
  
     _bt_relbuf(rel, subtreeparent);
     return true;
 }

References _bt_lock_subtree_parent(), _bt_relbuf(), _bt_rightsib_halfdeadflag(), Assert(), BTP_HALF_DEAD, BTPageGetOpaque, BTPageOpaqueData::btpo_flags, BTPageOpaqueData::btpo_next, BTPageOpaqueData::btpo_prev, BTreeTupleGetDownLink(), BTreeTupleSetDownLink(), BTreeTupleSetTopParent(), BufferGetBlockNumber(), BufferGetPage(), DEBUG1, elog(), END_CRIT_SECTION, ereport, errcode(), errmsg_internal(), ERROR, IndexTupleSize, InvalidBlockNumber, xl_btree_mark_page_halfdead::leafblk, xl_btree_mark_page_halfdead::leftblk, MarkBufferDirty(), MemSet, OffsetNumberNext, P_FIRSTDATAKEY, P_HIKEY, P_IGNORE, P_ISLEAF, P_ISROOT, P_RIGHTMOST, PageGetItem(), PageGetItemId(), PageGetMaxOffsetNumber(), PageIndexTupleDelete(), PageIndexTupleOverwrite(), PageSetLSN(), xl_btree_mark_page_halfdead::poffset, PredicateLockPageCombine(), REGBUF_STANDARD, REGBUF_WILL_INIT, RelationGetRelationName, RelationNeedsWAL, xl_btree_mark_page_halfdead::rightblk, SizeOfBtreeMarkPageHalfDead, START_CRIT_SECTION, IndexTupleData::t_info, xl_btree_mark_page_halfdead::topparent, XLOG_BTREE_MARK_PAGE_HALFDEAD, XLogBeginInsert(), XLogInsert(), XLogRegisterBuffer(), and XLogRegisterData().

Referenced by _bt_pagedel().

◆ _bt_metaversion()

void _bt_metaversion	(	Relation	rel,
		bool *	heapkeyspace,
		bool *	allequalimage
	)

Definition at line 736 of file nbtpage.c.

 {
     BTMetaPageData *metad;
  
     if (rel->rd_amcache == NULL)
     {
         Buffer      metabuf;
  
         metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
         metad = _bt_getmeta(rel, metabuf);
  
         /*
          * If there's no root page yet, _bt_getroot() doesn't expect a cache
          * to be made, so just stop here.  (XXX perhaps _bt_getroot() should
          * be changed to allow this case.)
          */
         if (metad->btm_root == P_NONE)
         {
             *heapkeyspace = metad->btm_version > BTREE_NOVAC_VERSION;
             *allequalimage = metad->btm_allequalimage;
  
             _bt_relbuf(rel, metabuf);
             return;
         }
  
         /*
          * Cache the metapage data for next time
          *
          * An on-the-fly version upgrade performed by _bt_upgrademetapage()
          * can change the nbtree version for an index without invalidating any
          * local cache.  This is okay because it can only happen when moving
          * from version 2 to version 3, both of which are !heapkeyspace
          * versions.
          */
         rel->rd_amcache = MemoryContextAlloc(rel->rd_indexcxt,
                                              sizeof(BTMetaPageData));
         memcpy(rel->rd_amcache, metad, sizeof(BTMetaPageData));
         _bt_relbuf(rel, metabuf);
     }
  
     /* Get cached page */
     metad = (BTMetaPageData *) rel->rd_amcache;
     /* We shouldn't have cached it if any of these fail */
     Assert(metad->btm_magic == BTREE_MAGIC);
     Assert(metad->btm_version >= BTREE_MIN_VERSION);
     Assert(metad->btm_version <= BTREE_VERSION);
     Assert(!metad->btm_allequalimage ||
            metad->btm_version > BTREE_NOVAC_VERSION);
     Assert(metad->btm_fastroot != P_NONE);
  
     *heapkeyspace = metad->btm_version > BTREE_NOVAC_VERSION;
     *allequalimage = metad->btm_allequalimage;
 }

References _bt_getbuf(), _bt_getmeta(), _bt_relbuf(), Assert(), BT_READ, BTMetaPageData::btm_allequalimage, BTMetaPageData::btm_fastroot, BTMetaPageData::btm_magic, BTMetaPageData::btm_root, BTMetaPageData::btm_version, BTREE_MAGIC, BTREE_METAPAGE, BTREE_MIN_VERSION, BTREE_NOVAC_VERSION, BTREE_VERSION, MemoryContextAlloc(), P_NONE, RelationData::rd_amcache, and RelationData::rd_indexcxt.

Referenced by _bt_first(), _bt_mkscankey(), and bt_index_check_internal().

◆ _bt_pagedel()

void _bt_pagedel	(	Relation	rel,
		Buffer	leafbuf,
		BTVacState *	vstate
	)

Definition at line 1816 of file nbtpage.c.

 {
     BlockNumber rightsib;
     bool        rightsib_empty;
     Page        page;
     BTPageOpaque opaque;
  
     /*
      * Save original leafbuf block number from caller.  Only deleted blocks
      * that are <= scanblkno are added to bulk delete stat's pages_deleted
      * count.
      */
     BlockNumber scanblkno = BufferGetBlockNumber(leafbuf);
  
     /*
      * "stack" is a search stack leading (approximately) to the target page.
      * It is initially NULL, but when iterating, we keep it to avoid
      * duplicated search effort.
      *
      * Also, when "stack" is not NULL, we have already checked that the
      * current page is not the right half of an incomplete split, i.e. the
      * left sibling does not have its INCOMPLETE_SPLIT flag set, including
      * when the current target page is to the right of caller's initial page
      * (the scanblkno page).
      */
     BTStack     stack = NULL;
  
     for (;;)
     {
         page = BufferGetPage(leafbuf);
         opaque = BTPageGetOpaque(page);
  
         /*
          * Internal pages are never deleted directly, only as part of deleting
          * the whole subtree all the way down to leaf level.
          *
          * Also check for deleted pages here.  Caller never passes us a fully
          * deleted page.  Only VACUUM can delete pages, so there can't have
          * been a concurrent deletion.  Assume that we reached any deleted
          * page encountered here by following a sibling link, and that the
          * index is corrupt.
          */
         Assert(!P_ISDELETED(opaque));
         if (!P_ISLEAF(opaque) || P_ISDELETED(opaque))
         {
             /*
              * Pre-9.4 page deletion only marked internal pages as half-dead,
              * but now we only use that flag on leaf pages. The old algorithm
              * was never supposed to leave half-dead pages in the tree, it was
              * just a transient state, but it was nevertheless possible in
              * error scenarios. We don't know how to deal with them here. They
              * are harmless as far as searches are considered, but inserts
              * into the deleted keyspace could add out-of-order downlinks in
              * the upper levels. Log a notice, hopefully the admin will notice
              * and reindex.
              */
             if (P_ISHALFDEAD(opaque))
                 ereport(LOG,
                         (errcode(ERRCODE_INDEX_CORRUPTED),
                          errmsg("index \"%s\" contains a half-dead internal page",
                                 RelationGetRelationName(rel)),
                          errhint("This can be caused by an interrupted VACUUM in version 9.3 or older, before upgrade. Please REINDEX it.")));
  
             if (P_ISDELETED(opaque))
                 ereport(LOG,
                         (errcode(ERRCODE_INDEX_CORRUPTED),
                          errmsg_internal("found deleted block %u while following right link from block %u in index \"%s\"",
                                          BufferGetBlockNumber(leafbuf),
                                          scanblkno,
                                          RelationGetRelationName(rel))));
  
             _bt_relbuf(rel, leafbuf);
             return;
         }
  
         /*
          * We can never delete rightmost pages nor root pages.  While at it,
          * check that page is empty, since it's possible that the leafbuf page
          * was empty a moment ago, but has since had some inserts.
          *
          * To keep the algorithm simple, we also never delete an incompletely
          * split page (they should be rare enough that this doesn't make any
          * meaningful difference to disk usage):
          *
          * The INCOMPLETE_SPLIT flag on the page tells us if the page is the
          * left half of an incomplete split, but ensuring that it's not the
          * right half is more complicated.  For that, we have to check that
          * the left sibling doesn't have its INCOMPLETE_SPLIT flag set using
          * _bt_leftsib_splitflag().  On the first iteration, we temporarily
          * release the lock on scanblkno/leafbuf, check the left sibling, and
          * construct a search stack to scanblkno.  On subsequent iterations,
          * we know we stepped right from a page that passed these tests, so
          * it's OK.
          */
         if (P_RIGHTMOST(opaque) || P_ISROOT(opaque) ||
             P_FIRSTDATAKEY(opaque) <= PageGetMaxOffsetNumber(page) ||
             P_INCOMPLETE_SPLIT(opaque))
         {
             /* Should never fail to delete a half-dead page */
             Assert(!P_ISHALFDEAD(opaque));
  
             _bt_relbuf(rel, leafbuf);
             return;
         }
  
         /*
          * First, remove downlink pointing to the page (or a parent of the
          * page, if we are going to delete a taller subtree), and mark the
          * leafbuf page half-dead
          */
         if (!P_ISHALFDEAD(opaque))
         {
             /*
              * We need an approximate pointer to the page's parent page.  We
              * use a variant of the standard search mechanism to search for
              * the page's high key; this will give us a link to either the
              * current parent or someplace to its left (if there are multiple
              * equal high keys, which is possible with !heapkeyspace indexes).
              *
              * Also check if this is the right-half of an incomplete split
              * (see comment above).
              */
             if (!stack)
             {
                 BTScanInsert itup_key;
                 ItemId      itemid;
                 IndexTuple  targetkey;
                 BlockNumber leftsib,
                             leafblkno;
                 Buffer      sleafbuf;
  
                 itemid = PageGetItemId(page, P_HIKEY);
                 targetkey = CopyIndexTuple((IndexTuple) PageGetItem(page, itemid));
  
                 leftsib = opaque->btpo_prev;
                 leafblkno = BufferGetBlockNumber(leafbuf);
  
                 /*
                  * To avoid deadlocks, we'd better drop the leaf page lock
                  * before going further.
                  */
                 _bt_unlockbuf(rel, leafbuf);
  
                 /*
                  * Check that the left sibling of leafbuf (if any) is not
                  * marked with INCOMPLETE_SPLIT flag before proceeding
                  */
                 Assert(leafblkno == scanblkno);
                 if (_bt_leftsib_splitflag(rel, leftsib, leafblkno))
                 {
                     ReleaseBuffer(leafbuf);
                     return;
                 }
  
                 /* we need an insertion scan key for the search, so build one */
                 itup_key = _bt_mkscankey(rel, targetkey);
                 /* find the leftmost leaf page with matching pivot/high key */
                 itup_key->pivotsearch = true;
                 stack = _bt_search(rel, itup_key, &sleafbuf, BT_READ, NULL);
                 /* won't need a second lock or pin on leafbuf */
                 _bt_relbuf(rel, sleafbuf);
  
                 /*
                  * Re-lock the leaf page, and start over to use our stack
                  * within _bt_mark_page_halfdead.  We must do it that way
                  * because it's possible that leafbuf can no longer be
                  * deleted.  We need to recheck.
                  *
                  * Note: We can't simply hold on to the sleafbuf lock instead,
                  * because it's barely possible that sleafbuf is not the same
                  * page as leafbuf.  This happens when leafbuf split after our
                  * original lock was dropped, but before _bt_search finished
                  * its descent.  We rely on the assumption that we'll find
                  * leafbuf isn't safe to delete anymore in this scenario.
                  * (Page deletion can cope with the stack being to the left of
                  * leafbuf, but not to the right of leafbuf.)
                  */
                 _bt_lockbuf(rel, leafbuf, BT_WRITE);
                 continue;
             }
  
             /*
              * See if it's safe to delete the leaf page, and determine how
              * many parent/internal pages above the leaf level will be
              * deleted.  If it's safe then _bt_mark_page_halfdead will also
              * perform the first phase of deletion, which includes marking the
              * leafbuf page half-dead.
              */
             Assert(P_ISLEAF(opaque) && !P_IGNORE(opaque));
             if (!_bt_mark_page_halfdead(rel, leafbuf, stack))
             {
                 _bt_relbuf(rel, leafbuf);
                 return;
             }
         }
  
         /*
          * Then unlink it from its siblings.  Each call to
          * _bt_unlink_halfdead_page unlinks the topmost page from the subtree,
          * making it shallower.  Iterate until the leafbuf page is deleted.
          */
         rightsib_empty = false;
         Assert(P_ISLEAF(opaque) && P_ISHALFDEAD(opaque));
         while (P_ISHALFDEAD(opaque))
         {
             /* Check for interrupts in _bt_unlink_halfdead_page */
             if (!_bt_unlink_halfdead_page(rel, leafbuf, scanblkno,
                                           &rightsib_empty, vstate))
             {
                 /*
                  * _bt_unlink_halfdead_page should never fail, since we
                  * established that deletion is generally safe in
                  * _bt_mark_page_halfdead -- index must be corrupt.
                  *
                  * Note that _bt_unlink_halfdead_page already released the
                  * lock and pin on leafbuf for us.
                  */
                 Assert(false);
                 return;
             }
         }
  
         Assert(P_ISLEAF(opaque) && P_ISDELETED(opaque));
  
         rightsib = opaque->btpo_next;
  
         _bt_relbuf(rel, leafbuf);
  
         /*
          * Check here, as calling loops will have locks held, preventing
          * interrupts from being processed.
          */
         CHECK_FOR_INTERRUPTS();
  
         /*
          * The page has now been deleted. If its right sibling is completely
          * empty, it's possible that the reason we haven't deleted it earlier
          * is that it was the rightmost child of the parent. Now that we
          * removed the downlink for this page, the right sibling might now be
          * the only child of the parent, and could be removed. It would be
          * picked up by the next vacuum anyway, but might as well try to
          * remove it now, so loop back to process the right sibling.
          *
          * Note: This relies on the assumption that _bt_getstackbuf() will be
          * able to reuse our original descent stack with a different child
          * block (provided that the child block is to the right of the
          * original leaf page reached by _bt_search()). It will even update
          * the descent stack each time we loop around, avoiding repeated work.
          */
         if (!rightsib_empty)
             break;
  
         leafbuf = _bt_getbuf(rel, rightsib, BT_WRITE);
     }
 }

References _bt_getbuf(), _bt_leftsib_splitflag(), _bt_lockbuf(), _bt_mark_page_halfdead(), _bt_mkscankey(), _bt_relbuf(), _bt_search(), _bt_unlink_halfdead_page(), _bt_unlockbuf(), Assert(), BT_READ, BT_WRITE, BTPageGetOpaque, BTPageOpaqueData::btpo_next, BTPageOpaqueData::btpo_prev, BufferGetBlockNumber(), BufferGetPage(), CHECK_FOR_INTERRUPTS, CopyIndexTuple(), ereport, errcode(), errhint(), errmsg(), errmsg_internal(), LOG, P_FIRSTDATAKEY, P_HIKEY, P_IGNORE, P_INCOMPLETE_SPLIT, P_ISDELETED, P_ISHALFDEAD, P_ISLEAF, P_ISROOT, P_RIGHTMOST, PageGetItem(), PageGetItemId(), PageGetMaxOffsetNumber(), BTScanInsertData::pivotsearch, RelationGetRelationName, and ReleaseBuffer().

Referenced by btvacuumpage().

◆ _bt_pageinit()

void _bt_pageinit	(	Page	page,
		Size	size
	)

Definition at line 1141 of file nbtpage.c.

 {
     PageInit(page, size, sizeof(BTPageOpaqueData));
 }

References PageInit().

Referenced by _bt_blnewpage(), _bt_getbuf(), _bt_initmetapage(), _bt_restore_meta(), _bt_split(), btree_xlog_mark_page_halfdead(), btree_xlog_newroot(), btree_xlog_split(), and btree_xlog_unlink_page().

◆ _bt_pendingfsm_add()

static void _bt_pendingfsm_add	(	BTVacState *	vstate,
		BlockNumber	target,
		FullTransactionId	safexid
	)

static

Definition at line 3021 of file nbtpage.c.

 {
     Assert(vstate->npendingpages <= vstate->bufsize);
     Assert(vstate->bufsize <= vstate->maxbufsize);
  
 #ifdef USE_ASSERT_CHECKING
  
     /*
      * Verify an assumption made by _bt_pendingfsm_finalize(): pages from the
      * array will always be in safexid order (since that is the order that we
      * save them in here)
      */
     if (vstate->npendingpages > 0)
     {
         FullTransactionId lastsafexid =
         vstate->pendingpages[vstate->npendingpages - 1].safexid;
  
         Assert(FullTransactionIdFollowsOrEquals(safexid, lastsafexid));
     }
 #endif
  
     /*
      * If temp buffer reaches maxbufsize/work_mem capacity then we discard
      * information about this page.
      *
      * Note that this also covers the case where we opted to not use the
      * optimization in _bt_pendingfsm_init().
      */
     if (vstate->npendingpages == vstate->maxbufsize)
         return;
  
     /* Consider enlarging buffer */
     if (vstate->npendingpages == vstate->bufsize)
     {
         int         newbufsize = vstate->bufsize * 2;
  
         /* Respect work_mem */
         if (newbufsize > vstate->maxbufsize)
             newbufsize = vstate->maxbufsize;
  
         vstate->bufsize = newbufsize;
         vstate->pendingpages =
             repalloc(vstate->pendingpages,
                      sizeof(BTPendingFSM) * vstate->bufsize);
     }
  
     /* Save metadata for newly deleted page */
     vstate->pendingpages[vstate->npendingpages].target = target;
     vstate->pendingpages[vstate->npendingpages].safexid = safexid;
     vstate->npendingpages++;
 }

References Assert(), BTVacState::bufsize, FullTransactionIdFollowsOrEquals, BTVacState::maxbufsize, BTVacState::npendingpages, BTVacState::pendingpages, repalloc(), BTPendingFSM::safexid, and BTPendingFSM::target.

Referenced by _bt_unlink_halfdead_page().

◆ _bt_pendingfsm_finalize()

void _bt_pendingfsm_finalize	(	Relation	rel,
		BTVacState *	vstate
	)

Definition at line 2956 of file nbtpage.c.

 {
     IndexBulkDeleteResult *stats = vstate->stats;
  
     Assert(stats->pages_newly_deleted >= vstate->npendingpages);
  
     if (vstate->npendingpages == 0)
     {
         /* Just free memory when nothing to do */
         if (vstate->pendingpages)
             pfree(vstate->pendingpages);
  
         return;
     }
  
 #ifdef DEBUG_BTREE_PENDING_FSM
  
     /*
      * Debugging aid: Sleep for 5 seconds to greatly increase the chances of
      * placing pending pages in the FSM.  Note that the optimization will
      * never be effective without some other backend concurrently consuming an
      * XID.
      */
     pg_usleep(5000000L);
 #endif
  
     /*
      * Recompute VACUUM XID boundaries.
      *
      * We don't actually care about the oldest non-removable XID.  Computing
      * the oldest such XID has a useful side-effect that we rely on: it
      * forcibly updates the XID horizon state for this backend.  This step is
      * essential; GlobalVisCheckRemovableFullXid() will not reliably recognize
      * that it is now safe to recycle newly deleted pages without this step.
      */
     GetOldestNonRemovableTransactionId(NULL);
  
     for (int i = 0; i < vstate->npendingpages; i++)
     {
         BlockNumber target = vstate->pendingpages[i].target;
         FullTransactionId safexid = vstate->pendingpages[i].safexid;
  
         /*
          * Do the equivalent of checking BTPageIsRecyclable(), but without
          * accessing the page again a second time.
          *
          * Give up on finding the first non-recyclable page -- all later pages
          * must be non-recyclable too, since _bt_pendingfsm_add() adds pages
          * to the array in safexid order.
          */
         if (!GlobalVisCheckRemovableFullXid(NULL, safexid))
             break;
  
         RecordFreeIndexPage(rel, target);
         stats->pages_free++;
     }
  
     pfree(vstate->pendingpages);
 }

References Assert(), GetOldestNonRemovableTransactionId(), GlobalVisCheckRemovableFullXid(), i, BTVacState::npendingpages, IndexBulkDeleteResult::pages_free, IndexBulkDeleteResult::pages_newly_deleted, BTVacState::pendingpages, pfree(), pg_usleep(), RecordFreeIndexPage(), BTPendingFSM::safexid, BTVacState::stats, and BTPendingFSM::target.

Referenced by btvacuumscan().

◆ _bt_pendingfsm_init()

void _bt_pendingfsm_init	(	Relation	rel,
		BTVacState *	vstate,
		bool	cleanuponly
	)

Definition at line 2915 of file nbtpage.c.

 {
     int64       maxbufsize;
  
     /*
      * Don't bother with optimization in cleanup-only case -- we don't expect
      * any newly deleted pages.  Besides, cleanup-only calls to btvacuumscan()
      * can only take place because this optimization didn't work out during
      * the last VACUUM.
      */
     if (cleanuponly)
         return;
  
     /*
      * Cap maximum size of array so that we always respect work_mem.  Avoid
      * int overflow here.
      */
     vstate->bufsize = 256;
     maxbufsize = (work_mem * 1024L) / sizeof(BTPendingFSM);
     maxbufsize = Min(maxbufsize, INT_MAX);
     maxbufsize = Min(maxbufsize, MaxAllocSize / sizeof(BTPendingFSM));
     /* Stay sane with small work_mem */
     maxbufsize = Max(maxbufsize, vstate->bufsize);
     vstate->maxbufsize = maxbufsize;
  
     /* Allocate buffer, indicate that there are currently 0 pending pages */
     vstate->pendingpages = palloc(sizeof(BTPendingFSM) * vstate->bufsize);
     vstate->npendingpages = 0;
 }

References BTVacState::bufsize, Max, MaxAllocSize, BTVacState::maxbufsize, Min, BTVacState::npendingpages, palloc(), BTVacState::pendingpages, and work_mem.

Referenced by btvacuumscan().

◆ _bt_relandgetbuf()

Buffer _bt_relandgetbuf	(	Relation	rel,
		Buffer	obuf,
		BlockNumber	blkno,
		int	access
	)

Definition at line 1015 of file nbtpage.c.

 {
     Buffer      buf;
  
     Assert(blkno != P_NEW);
     if (BufferIsValid(obuf))
         _bt_unlockbuf(rel, obuf);
     buf = ReleaseAndReadBuffer(obuf, rel, blkno);
     _bt_lockbuf(rel, buf, access);
  
     _bt_checkpage(rel, buf);
     return buf;
 }

References _bt_checkpage(), _bt_lockbuf(), _bt_unlockbuf(), Assert(), buf, BufferIsValid(), P_NEW, and ReleaseAndReadBuffer().

Referenced by _bt_check_unique(), _bt_get_endpoint(), _bt_getroot(), _bt_gettrueroot(), _bt_moveright(), _bt_search(), _bt_stepright(), and _bt_walk_left().

◆ _bt_relbuf()

void _bt_relbuf	(	Relation	rel,
		Buffer	buf
	)

Definition at line 1035 of file nbtpage.c.

 {
     _bt_unlockbuf(rel, buf);
     ReleaseBuffer(buf);
 }

References _bt_unlockbuf(), buf, and ReleaseBuffer().

Referenced by _bt_check_unique(), _bt_doinsert(), _bt_finish_split(), _bt_getbuf(), _bt_getroot(), _bt_getrootheight(), _bt_getstackbuf(), _bt_gettrueroot(), _bt_insert_parent(), _bt_insertonpg(), _bt_killitems(), _bt_leftsib_splitflag(), _bt_lock_subtree_parent(), _bt_mark_page_halfdead(), _bt_metaversion(), _bt_moveright(), _bt_newroot(), _bt_pagedel(), _bt_readnextpage(), _bt_rightsib_halfdeadflag(), _bt_search_insert(), _bt_set_cleanup_info(), _bt_split(), _bt_stepright(), _bt_unlink_halfdead_page(), _bt_vacuum_needs_cleanup(), _bt_walk_left(), bt_rootdescend(), btvacuumpage(), and pgstat_btree_page().

◆ _bt_rightsib_halfdeadflag()

static bool _bt_rightsib_halfdeadflag	(	Relation	rel,
		BlockNumber	leafrightsib
	)

static

Definition at line 1766 of file nbtpage.c.

 {
     Buffer      buf;
     Page        page;
     BTPageOpaque opaque;
     bool        result;
  
     Assert(leafrightsib != P_NONE);
  
     buf = _bt_getbuf(rel, leafrightsib, BT_READ);
     page = BufferGetPage(buf);
     opaque = BTPageGetOpaque(page);
  
     Assert(P_ISLEAF(opaque) && !P_ISDELETED(opaque));
     result = P_ISHALFDEAD(opaque);
     _bt_relbuf(rel, buf);
  
     return result;
 }

References _bt_getbuf(), _bt_relbuf(), Assert(), BT_READ, BTPageGetOpaque, buf, BufferGetPage(), P_ISDELETED, P_ISHALFDEAD, P_ISLEAF, and P_NONE.

Referenced by _bt_mark_page_halfdead().

◆ _bt_set_cleanup_info()

void _bt_set_cleanup_info	(	Relation	rel,
		BlockNumber	num_delpages
	)

Definition at line 234 of file nbtpage.c.

 {
     Buffer      metabuf;
     Page        metapg;
     BTMetaPageData *metad;
  
     /*
      * On-disk compatibility note: The btm_last_cleanup_num_delpages metapage
      * field started out as a TransactionId field called btm_oldest_btpo_xact.
      * Both "versions" are just uint32 fields.  It was convenient to repurpose
      * the field when we began to use 64-bit XIDs in deleted pages.
      *
      * It's possible that a pg_upgrade'd database will contain an XID value in
      * what is now recognized as the metapage's btm_last_cleanup_num_delpages
      * field.  _bt_vacuum_needs_cleanup() may even believe that this value
      * indicates that there are lots of pages that it needs to recycle, when
      * in reality there are only one or two.  The worst that can happen is
      * that there will be a call to btvacuumscan a little earlier, which will
      * set btm_last_cleanup_num_delpages to a sane value when we're called.
      *
      * Note also that the metapage's btm_last_cleanup_num_heap_tuples field is
      * no longer used as of PostgreSQL 14.  We set it to -1.0 on rewrite, just
      * to be consistent.
      */
     metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
     metapg = BufferGetPage(metabuf);
     metad = BTPageGetMeta(metapg);
  
     /* Don't miss chance to upgrade index/metapage when BTREE_MIN_VERSION */
     if (metad->btm_version >= BTREE_NOVAC_VERSION &&
         metad->btm_last_cleanup_num_delpages == num_delpages)
     {
         /* Usually means index continues to have num_delpages of 0 */
         _bt_relbuf(rel, metabuf);
         return;
     }
  
     /* trade in our read lock for a write lock */
     _bt_unlockbuf(rel, metabuf);
     _bt_lockbuf(rel, metabuf, BT_WRITE);
  
     START_CRIT_SECTION();
  
     /* upgrade meta-page if needed */
     if (metad->btm_version < BTREE_NOVAC_VERSION)
         _bt_upgrademetapage(metapg);
  
     /* update cleanup-related information */
     metad->btm_last_cleanup_num_delpages = num_delpages;
     metad->btm_last_cleanup_num_heap_tuples = -1.0;
     MarkBufferDirty(metabuf);
  
     /* write wal record if needed */
     if (RelationNeedsWAL(rel))
     {
         xl_btree_metadata md;
         XLogRecPtr  recptr;
  
         XLogBeginInsert();
         XLogRegisterBuffer(0, metabuf, REGBUF_WILL_INIT | REGBUF_STANDARD);
  
         Assert(metad->btm_version >= BTREE_NOVAC_VERSION);
         md.version = metad->btm_version;
         md.root = metad->btm_root;
         md.level = metad->btm_level;
         md.fastroot = metad->btm_fastroot;
         md.fastlevel = metad->btm_fastlevel;
         md.last_cleanup_num_delpages = num_delpages;
         md.allequalimage = metad->btm_allequalimage;
  
         XLogRegisterBufData(0, (char *) &md, sizeof(xl_btree_metadata));
  
         recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_META_CLEANUP);
  
         PageSetLSN(metapg, recptr);
     }
  
     END_CRIT_SECTION();
  
     _bt_relbuf(rel, metabuf);
 }

Referenced by btvacuumcleanup().

◆ _bt_unlink_halfdead_page()

static bool _bt_unlink_halfdead_page	(	Relation	rel,
		Buffer	leafbuf,
		BlockNumber	scanblkno,
		bool *	rightsib_empty,
		BTVacState *	vstate
	)

static

Definition at line 2303 of file nbtpage.c.

 {
     BlockNumber leafblkno = BufferGetBlockNumber(leafbuf);
     IndexBulkDeleteResult *stats = vstate->stats;
     BlockNumber leafleftsib;
     BlockNumber leafrightsib;
     BlockNumber target;
     BlockNumber leftsib;
     BlockNumber rightsib;
     Buffer      lbuf = InvalidBuffer;
     Buffer      buf;
     Buffer      rbuf;
     Buffer      metabuf = InvalidBuffer;
     Page        metapg = NULL;
     BTMetaPageData *metad = NULL;
     ItemId      itemid;
     Page        page;
     BTPageOpaque opaque;
     FullTransactionId safexid;
     bool        rightsib_is_rightmost;
     uint32      targetlevel;
     IndexTuple  leafhikey;
     BlockNumber leaftopparent;
  
     page = BufferGetPage(leafbuf);
     opaque = BTPageGetOpaque(page);
  
     Assert(P_ISLEAF(opaque) && !P_ISDELETED(opaque) && P_ISHALFDEAD(opaque));
  
     /*
      * Remember some information about the leaf page.
      */
     itemid = PageGetItemId(page, P_HIKEY);
     leafhikey = (IndexTuple) PageGetItem(page, itemid);
     target = BTreeTupleGetTopParent(leafhikey);
     leafleftsib = opaque->btpo_prev;
     leafrightsib = opaque->btpo_next;
  
     _bt_unlockbuf(rel, leafbuf);
  
     /*
      * Check here, as calling loops will have locks held, preventing
      * interrupts from being processed.
      */
     CHECK_FOR_INTERRUPTS();
  
     /* Unlink the current top parent of the subtree */
     if (!BlockNumberIsValid(target))
     {
         /* Target is leaf page (or leaf page is top parent, if you prefer) */
         target = leafblkno;
  
         buf = leafbuf;
         leftsib = leafleftsib;
         targetlevel = 0;
     }
     else
     {
         /* Target is the internal page taken from leaf's top parent link */
         Assert(target != leafblkno);
  
         /* Fetch the block number of the target's left sibling */
         buf = _bt_getbuf(rel, target, BT_READ);
         page = BufferGetPage(buf);
         opaque = BTPageGetOpaque(page);
         leftsib = opaque->btpo_prev;
         targetlevel = opaque->btpo_level;
         Assert(targetlevel > 0);
  
         /*
          * To avoid deadlocks, we'd better drop the target page lock before
          * going further.
          */
         _bt_unlockbuf(rel, buf);
     }
  
     /*
      * We have to lock the pages we need to modify in the standard order:
      * moving right, then up.  Else we will deadlock against other writers.
      *
      * So, first lock the leaf page, if it's not the target.  Then find and
      * write-lock the current left sibling of the target page.  The sibling
      * that was current a moment ago could have split, so we may have to move
      * right.
      */
     if (target != leafblkno)
         _bt_lockbuf(rel, leafbuf, BT_WRITE);
     if (leftsib != P_NONE)
     {
         lbuf = _bt_getbuf(rel, leftsib, BT_WRITE);
         page = BufferGetPage(lbuf);
         opaque = BTPageGetOpaque(page);
         while (P_ISDELETED(opaque) || opaque->btpo_next != target)
         {
             bool        leftsibvalid = true;
  
             /*
              * Before we follow the link from the page that was the left
              * sibling mere moments ago, validate its right link.  This
              * reduces the opportunities for loop to fail to ever make any
              * progress in the presence of index corruption.
              *
              * Note: we rely on the assumption that there can only be one
              * vacuum process running at a time (against the same index).
              */
             if (P_RIGHTMOST(opaque) || P_ISDELETED(opaque) ||
                 leftsib == opaque->btpo_next)
                 leftsibvalid = false;
  
             leftsib = opaque->btpo_next;
             _bt_relbuf(rel, lbuf);
  
             if (!leftsibvalid)
             {
                 if (target != leafblkno)
                 {
                     /* we have only a pin on target, but pin+lock on leafbuf */
                     ReleaseBuffer(buf);
                     _bt_relbuf(rel, leafbuf);
                 }
                 else
                 {
                     /* we have only a pin on leafbuf */
                     ReleaseBuffer(leafbuf);
                 }
  
                 ereport(LOG,
                         (errcode(ERRCODE_INDEX_CORRUPTED),
                          errmsg_internal("valid left sibling for deletion target could not be located: "
                                          "left sibling %u of target %u with leafblkno %u and scanblkno %u in index \"%s\"",
                                          leftsib, target, leafblkno, scanblkno,
                                          RelationGetRelationName(rel))));
  
                 return false;
             }
  
             CHECK_FOR_INTERRUPTS();
  
             /* step right one page */
             lbuf = _bt_getbuf(rel, leftsib, BT_WRITE);
             page = BufferGetPage(lbuf);
             opaque = BTPageGetOpaque(page);
         }
     }
     else
         lbuf = InvalidBuffer;
  
     /* Next write-lock the target page itself */
     _bt_lockbuf(rel, buf, BT_WRITE);
     page = BufferGetPage(buf);
     opaque = BTPageGetOpaque(page);
  
     /*
      * Check page is still empty etc, else abandon deletion.  This is just for
      * paranoia's sake; a half-dead page cannot resurrect because there can be
      * only one vacuum process running at a time.
      */
     if (P_RIGHTMOST(opaque) || P_ISROOT(opaque) || P_ISDELETED(opaque))
         elog(ERROR, "target page changed status unexpectedly in block %u of index \"%s\"",
              target, RelationGetRelationName(rel));
  
     if (opaque->btpo_prev != leftsib)
         ereport(ERROR,
                 (errcode(ERRCODE_INDEX_CORRUPTED),
                  errmsg_internal("target page left link unexpectedly changed from %u to %u in block %u of index \"%s\"",
                                  leftsib, opaque->btpo_prev, target,
                                  RelationGetRelationName(rel))));
  
     if (target == leafblkno)
     {
         if (P_FIRSTDATAKEY(opaque) <= PageGetMaxOffsetNumber(page) ||
             !P_ISLEAF(opaque) || !P_ISHALFDEAD(opaque))
             elog(ERROR, "target leaf page changed status unexpectedly in block %u of index \"%s\"",
                  target, RelationGetRelationName(rel));
  
         /* Leaf page is also target page: don't set leaftopparent */
         leaftopparent = InvalidBlockNumber;
     }
     else
     {
         IndexTuple  finaldataitem;
  
         if (P_FIRSTDATAKEY(opaque) != PageGetMaxOffsetNumber(page) ||
             P_ISLEAF(opaque))
             elog(ERROR, "target internal page on level %u changed status unexpectedly in block %u of index \"%s\"",
                  targetlevel, target, RelationGetRelationName(rel));
  
         /* Target is internal: set leaftopparent for next call here...  */
         itemid = PageGetItemId(page, P_FIRSTDATAKEY(opaque));
         finaldataitem = (IndexTuple) PageGetItem(page, itemid);
         leaftopparent = BTreeTupleGetDownLink(finaldataitem);
         /* ...except when it would be a redundant pointer-to-self */
         if (leaftopparent == leafblkno)
             leaftopparent = InvalidBlockNumber;
     }
  
     /* No leaftopparent for level 0 (leaf page) or level 1 target */
     Assert(!BlockNumberIsValid(leaftopparent) || targetlevel > 1);
  
     /*
      * And next write-lock the (current) right sibling.
      */
     rightsib = opaque->btpo_next;
     rbuf = _bt_getbuf(rel, rightsib, BT_WRITE);
     page = BufferGetPage(rbuf);
     opaque = BTPageGetOpaque(page);
     if (opaque->btpo_prev != target)
         ereport(ERROR,
                 (errcode(ERRCODE_INDEX_CORRUPTED),
                  errmsg_internal("right sibling's left-link doesn't match: "
                                  "block %u links to %u instead of expected %u in index \"%s\"",
                                  rightsib, opaque->btpo_prev, target,
                                  RelationGetRelationName(rel))));
     rightsib_is_rightmost = P_RIGHTMOST(opaque);
     *rightsib_empty = (P_FIRSTDATAKEY(opaque) > PageGetMaxOffsetNumber(page));
  
     /*
      * If we are deleting the next-to-last page on the target's level, then
      * the rightsib is a candidate to become the new fast root. (In theory, it
      * might be possible to push the fast root even further down, but the odds
      * of doing so are slim, and the locking considerations daunting.)
      *
      * We can safely acquire a lock on the metapage here --- see comments for
      * _bt_newroot().
      */
     if (leftsib == P_NONE && rightsib_is_rightmost)
     {
         page = BufferGetPage(rbuf);
         opaque = BTPageGetOpaque(page);
         if (P_RIGHTMOST(opaque))
         {
             /* rightsib will be the only one left on the level */
             metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_WRITE);
             metapg = BufferGetPage(metabuf);
             metad = BTPageGetMeta(metapg);
  
             /*
              * The expected case here is btm_fastlevel == targetlevel+1; if
              * the fastlevel is <= targetlevel, something is wrong, and we
              * choose to overwrite it to fix it.
              */
             if (metad->btm_fastlevel > targetlevel + 1)
             {
                 /* no update wanted */
                 _bt_relbuf(rel, metabuf);
                 metabuf = InvalidBuffer;
             }
         }
     }
  
     /*
      * Here we begin doing the deletion.
      */
  
     /* No ereport(ERROR) until changes are logged */
     START_CRIT_SECTION();
  
     /*
      * Update siblings' side-links.  Note the target page's side-links will
      * continue to point to the siblings.  Asserts here are just rechecking
      * things we already verified above.
      */
     if (BufferIsValid(lbuf))
     {
         page = BufferGetPage(lbuf);
         opaque = BTPageGetOpaque(page);
         Assert(opaque->btpo_next == target);
         opaque->btpo_next = rightsib;
     }
     page = BufferGetPage(rbuf);
     opaque = BTPageGetOpaque(page);
     Assert(opaque->btpo_prev == target);
     opaque->btpo_prev = leftsib;
  
     /*
      * If we deleted a parent of the targeted leaf page, instead of the leaf
      * itself, update the leaf to point to the next remaining child in the
      * subtree.
      *
      * Note: We rely on the fact that a buffer pin on the leaf page has been
      * held since leafhikey was initialized.  This is safe, though only
      * because the page was already half-dead at that point.  The leaf page
      * cannot have been modified by any other backend during the period when
      * no lock was held.
      */
     if (target != leafblkno)
         BTreeTupleSetTopParent(leafhikey, leaftopparent);
  
     /*
      * Mark the page itself deleted.  It can be recycled when all current
      * transactions are gone.  Storing GetTopTransactionId() would work, but
      * we're in VACUUM and would not otherwise have an XID.  Having already
      * updated links to the target, ReadNextFullTransactionId() suffices as an
      * upper bound.  Any scan having retained a now-stale link is advertising
      * in its PGPROC an xmin less than or equal to the value we read here.  It
      * will continue to do so, holding back the xmin horizon, for the duration
      * of that scan.
      */
     page = BufferGetPage(buf);
     opaque = BTPageGetOpaque(page);
     Assert(P_ISHALFDEAD(opaque) || !P_ISLEAF(opaque));
  
     /*
      * Store upper bound XID that's used to determine when deleted page is no
      * longer needed as a tombstone
      */
     safexid = ReadNextFullTransactionId();
     BTPageSetDeleted(page, safexid);
     opaque->btpo_cycleid = 0;
  
     /* And update the metapage, if needed */
     if (BufferIsValid(metabuf))
     {
         /* upgrade metapage if needed */
         if (metad->btm_version < BTREE_NOVAC_VERSION)
             _bt_upgrademetapage(metapg);
         metad->btm_fastroot = rightsib;
         metad->btm_fastlevel = targetlevel;
         MarkBufferDirty(metabuf);
     }
  
     /* Must mark buffers dirty before XLogInsert */
     MarkBufferDirty(rbuf);
     MarkBufferDirty(buf);
     if (BufferIsValid(lbuf))
         MarkBufferDirty(lbuf);
     if (target != leafblkno)
         MarkBufferDirty(leafbuf);
  
     /* XLOG stuff */
     if (RelationNeedsWAL(rel))
     {
         xl_btree_unlink_page xlrec;
         xl_btree_metadata xlmeta;
         uint8       xlinfo;
         XLogRecPtr  recptr;
  
         XLogBeginInsert();
  
         XLogRegisterBuffer(0, buf, REGBUF_WILL_INIT);
         if (BufferIsValid(lbuf))
             XLogRegisterBuffer(1, lbuf, REGBUF_STANDARD);
         XLogRegisterBuffer(2, rbuf, REGBUF_STANDARD);
         if (target != leafblkno)
             XLogRegisterBuffer(3, leafbuf, REGBUF_WILL_INIT);
  
         /* information stored on the target/to-be-unlinked block */
         xlrec.leftsib = leftsib;
         xlrec.rightsib = rightsib;
         xlrec.level = targetlevel;
         xlrec.safexid = safexid;
  
         /* information needed to recreate the leaf block (if not the target) */
         xlrec.leafleftsib = leafleftsib;
         xlrec.leafrightsib = leafrightsib;
         xlrec.leaftopparent = leaftopparent;
  
         XLogRegisterData((char *) &xlrec, SizeOfBtreeUnlinkPage);
  
         if (BufferIsValid(metabuf))
         {
             XLogRegisterBuffer(4, metabuf, REGBUF_WILL_INIT | REGBUF_STANDARD);
  
             Assert(metad->btm_version >= BTREE_NOVAC_VERSION);
             xlmeta.version = metad->btm_version;
             xlmeta.root = metad->btm_root;
             xlmeta.level = metad->btm_level;
             xlmeta.fastroot = metad->btm_fastroot;
             xlmeta.fastlevel = metad->btm_fastlevel;
             xlmeta.last_cleanup_num_delpages = metad->btm_last_cleanup_num_delpages;
             xlmeta.allequalimage = metad->btm_allequalimage;
  
             XLogRegisterBufData(4, (char *) &xlmeta, sizeof(xl_btree_metadata));
             xlinfo = XLOG_BTREE_UNLINK_PAGE_META;
         }
         else
             xlinfo = XLOG_BTREE_UNLINK_PAGE;
  
         recptr = XLogInsert(RM_BTREE_ID, xlinfo);
  
         if (BufferIsValid(metabuf))
         {
             PageSetLSN(metapg, recptr);
         }
         page = BufferGetPage(rbuf);
         PageSetLSN(page, recptr);
         page = BufferGetPage(buf);
         PageSetLSN(page, recptr);
         if (BufferIsValid(lbuf))
         {
             page = BufferGetPage(lbuf);
             PageSetLSN(page, recptr);
         }
         if (target != leafblkno)
         {
             page = BufferGetPage(leafbuf);
             PageSetLSN(page, recptr);
         }
     }
  
     END_CRIT_SECTION();
  
     /* release metapage */
     if (BufferIsValid(metabuf))
         _bt_relbuf(rel, metabuf);
  
     /* release siblings */
     if (BufferIsValid(lbuf))
         _bt_relbuf(rel, lbuf);
     _bt_relbuf(rel, rbuf);
  
     /* If the target is not leafbuf, we're done with it now -- release it */
     if (target != leafblkno)
         _bt_relbuf(rel, buf);
  
     /*
      * Maintain pages_newly_deleted, which is simply the number of pages
      * deleted by the ongoing VACUUM operation.
      *
      * Maintain pages_deleted in a way that takes into account how
      * btvacuumpage() will count deleted pages that have yet to become
      * scanblkno -- only count page when it's not going to get that treatment
      * later on.
      */
     stats->pages_newly_deleted++;
     if (target <= scanblkno)
         stats->pages_deleted++;
  
     /*
      * Remember information about the target page (now a newly deleted page)
      * in dedicated vstate space for later.  The page will be considered as a
      * candidate to place in the FSM at the end of the current btvacuumscan()
      * call.
      */
     _bt_pendingfsm_add(vstate, target, safexid);
  
     return true;
 }

References _bt_getbuf(), _bt_lockbuf(), _bt_pendingfsm_add(), _bt_relbuf(), _bt_unlockbuf(), _bt_upgrademetapage(), xl_btree_metadata::allequalimage, Assert(), BlockNumberIsValid(), BT_READ, BT_WRITE, BTMetaPageData::btm_allequalimage, BTMetaPageData::btm_fastlevel, BTMetaPageData::btm_fastroot, BTMetaPageData::btm_last_cleanup_num_delpages, BTMetaPageData::btm_level, BTMetaPageData::btm_root, BTMetaPageData::btm_version, BTPageGetMeta, BTPageGetOpaque, BTPageSetDeleted(), BTPageOpaqueData::btpo_cycleid, BTPageOpaqueData::btpo_level, BTPageOpaqueData::btpo_next, BTPageOpaqueData::btpo_prev, BTREE_METAPAGE, BTREE_NOVAC_VERSION, BTreeTupleGetDownLink(), BTreeTupleGetTopParent(), BTreeTupleSetTopParent(), buf, BufferGetBlockNumber(), BufferGetPage(), BufferIsValid(), CHECK_FOR_INTERRUPTS, elog(), END_CRIT_SECTION, ereport, errcode(), errmsg_internal(), ERROR, xl_btree_metadata::fastlevel, xl_btree_metadata::fastroot, InvalidBlockNumber, InvalidBuffer, xl_btree_metadata::last_cleanup_num_delpages, xl_btree_unlink_page::leafleftsib, xl_btree_unlink_page::leafrightsib, xl_btree_unlink_page::leaftopparent, xl_btree_unlink_page::leftsib, xl_btree_metadata::level, xl_btree_unlink_page::level, LOG, MarkBufferDirty(), P_FIRSTDATAKEY, P_HIKEY, P_ISDELETED, P_ISHALFDEAD, P_ISLEAF, P_ISROOT, P_NONE, P_RIGHTMOST, PageGetItem(), PageGetItemId(), PageGetMaxOffsetNumber(), IndexBulkDeleteResult::pages_deleted, IndexBulkDeleteResult::pages_newly_deleted, PageSetLSN(), ReadNextFullTransactionId(), REGBUF_STANDARD, REGBUF_WILL_INIT, RelationGetRelationName, RelationNeedsWAL, ReleaseBuffer(), xl_btree_unlink_page::rightsib, xl_btree_metadata::root, xl_btree_unlink_page::safexid, SizeOfBtreeUnlinkPage, START_CRIT_SECTION, BTVacState::stats, xl_btree_metadata::version, XLOG_BTREE_UNLINK_PAGE, XLOG_BTREE_UNLINK_PAGE_META, XLogBeginInsert(), XLogInsert(), XLogRegisterBufData(), XLogRegisterBuffer(), and XLogRegisterData().

Referenced by _bt_pagedel().

◆ _bt_unlockbuf()

void _bt_unlockbuf	(	Relation	rel,
		Buffer	buf
	)

Definition at line 1082 of file nbtpage.c.

 {
     /*
      * Buffer is pinned and locked, which means that it is expected to be
      * defined and addressable.  Check that proactively.
      */
     VALGRIND_CHECK_MEM_IS_DEFINED(BufferGetPage(buf), BLCKSZ);
  
     /* LockBuffer() asserts that pin is held by this backend */
     LockBuffer(buf, BUFFER_LOCK_UNLOCK);
  
     if (!RelationUsesLocalBuffers(rel))
         VALGRIND_MAKE_MEM_NOACCESS(BufferGetPage(buf), BLCKSZ);
 }

References buf, BUFFER_LOCK_UNLOCK, BufferGetPage(), LockBuffer(), RelationUsesLocalBuffers, VALGRIND_CHECK_MEM_IS_DEFINED, and VALGRIND_MAKE_MEM_NOACCESS.

Referenced by _bt_drop_lock_and_maybe_pin(), _bt_endpoint(), _bt_first(), _bt_getroot(), _bt_killitems(), _bt_moveright(), _bt_pagedel(), _bt_relandgetbuf(), _bt_relbuf(), _bt_search(), _bt_set_cleanup_info(), and _bt_unlink_halfdead_page().

◆ _bt_upgradelockbufcleanup()

void _bt_upgradelockbufcleanup	(	Relation	rel,
		Buffer	buf
	)

Definition at line 1121 of file nbtpage.c.

 {
     /*
      * Buffer is pinned and locked, which means that it is expected to be
      * defined and addressable.  Check that proactively.
      */
     VALGRIND_CHECK_MEM_IS_DEFINED(BufferGetPage(buf), BLCKSZ);
  
     /* LockBuffer() asserts that pin is held by this backend */
     LockBuffer(buf, BUFFER_LOCK_UNLOCK);
     LockBufferForCleanup(buf);
 }

References buf, BUFFER_LOCK_UNLOCK, BufferGetPage(), LockBuffer(), LockBufferForCleanup(), and VALGRIND_CHECK_MEM_IS_DEFINED.

Referenced by btvacuumpage().

◆ _bt_upgrademetapage()

void _bt_upgrademetapage ( Page page )

Definition at line 109 of file nbtpage.c.

 {
     BTMetaPageData *metad;
     BTPageOpaque metaopaque PG_USED_FOR_ASSERTS_ONLY;
  
     metad = BTPageGetMeta(page);
     metaopaque = BTPageGetOpaque(page);
  
     /* It must be really a meta page of upgradable version */
     Assert(metaopaque->btpo_flags & BTP_META);
     Assert(metad->btm_version < BTREE_NOVAC_VERSION);
     Assert(metad->btm_version >= BTREE_MIN_VERSION);
  
     /* Set version number and fill extra fields added into version 3 */
     metad->btm_version = BTREE_NOVAC_VERSION;
     metad->btm_last_cleanup_num_delpages = 0;
     metad->btm_last_cleanup_num_heap_tuples = -1.0;
     /* Only a REINDEX can set this field */
     Assert(!metad->btm_allequalimage);
     metad->btm_allequalimage = false;
  
     /* Adjust pd_lower (see _bt_initmetapage() for details) */
     ((PageHeader) page)->pd_lower =
         ((char *) metad + sizeof(BTMetaPageData)) - (char *) page;
 }

References Assert(), BTMetaPageData::btm_allequalimage, BTMetaPageData::btm_last_cleanup_num_delpages, BTMetaPageData::btm_last_cleanup_num_heap_tuples, BTMetaPageData::btm_version, BTP_META, BTPageGetMeta, BTPageGetOpaque, BTREE_MIN_VERSION, BTREE_NOVAC_VERSION, and PG_USED_FOR_ASSERTS_ONLY.

Referenced by _bt_getroot(), _bt_insertonpg(), _bt_newroot(), _bt_set_cleanup_info(), and _bt_unlink_halfdead_page().

◆ _bt_vacuum_needs_cleanup()

bool _bt_vacuum_needs_cleanup ( Relation rel )

Definition at line 181 of file nbtpage.c.

 {
     Buffer      metabuf;
     Page        metapg;
     BTMetaPageData *metad;
     uint32      btm_version;
     BlockNumber prev_num_delpages;
  
     /*
      * Copy details from metapage to local variables quickly.
      *
      * Note that we deliberately avoid using cached version of metapage here.
      */
     metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
     metapg = BufferGetPage(metabuf);
     metad = BTPageGetMeta(metapg);
     btm_version = metad->btm_version;
  
     if (btm_version < BTREE_NOVAC_VERSION)
     {
         /*
          * Metapage needs to be dynamically upgraded to store fields that are
          * only present when btm_version >= BTREE_NOVAC_VERSION
          */
         _bt_relbuf(rel, metabuf);
         return true;
     }
  
     prev_num_delpages = metad->btm_last_cleanup_num_delpages;
     _bt_relbuf(rel, metabuf);
  
     /*
      * Trigger cleanup in rare cases where prev_num_delpages exceeds 5% of the
      * total size of the index.  We can reasonably expect (though are not
      * guaranteed) to be able to recycle this many pages if we decide to do a
      * btvacuumscan call during the ongoing btvacuumcleanup.  For further
      * details see the nbtree/README section on placing deleted pages in the
      * FSM.
      */
     if (prev_num_delpages > 0 &&
         prev_num_delpages > RelationGetNumberOfBlocks(rel) / 20)
         return true;
  
     return false;
 }

References _bt_getbuf(), _bt_relbuf(), BT_READ, BTMetaPageData::btm_last_cleanup_num_delpages, BTMetaPageData::btm_version, BTPageGetMeta, BTREE_METAPAGE, BTREE_NOVAC_VERSION, BufferGetPage(), and RelationGetNumberOfBlocks.

Referenced by btvacuumcleanup().

Functions

Function Documentation

◆ _bt_checkpage()

◆ _bt_conditionallockbuf()

◆ _bt_delitems_cmp()

◆ _bt_delitems_delete()

◆ _bt_delitems_delete_check()

◆ _bt_delitems_update()

◆ _bt_delitems_vacuum()

◆ _bt_getbuf()

◆ _bt_getmeta()

◆ _bt_getroot()

◆ _bt_getrootheight()

◆ _bt_gettrueroot()

◆ _bt_initmetapage()

◆ _bt_leftsib_splitflag()

◆ _bt_lock_subtree_parent()

◆ _bt_lockbuf()

◆ _bt_log_reuse_page()

◆ _bt_mark_page_halfdead()

◆ _bt_metaversion()

◆ _bt_pagedel()

◆ _bt_pageinit()

◆ _bt_pendingfsm_add()

◆ _bt_pendingfsm_finalize()

◆ _bt_pendingfsm_init()

◆ _bt_relandgetbuf()

◆ _bt_relbuf()

◆ _bt_rightsib_halfdeadflag()

◆ _bt_set_cleanup_info()

◆ _bt_unlink_halfdead_page()

◆ _bt_unlockbuf()

◆ _bt_upgradelockbufcleanup()

◆ _bt_upgrademetapage()

◆ _bt_vacuum_needs_cleanup()