greenplumn nbtree 源码
greenplumn nbtree 代码
文件路径：/src/backend/access/nbtree/nbtree.c
/*-------------------------------------------------------------------------
*
* nbtree.c
* Implementation of Lehman and Yao's btree management algorithm for
* Postgres.
*
* NOTES
* This file contains only the public interface routines.
*
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/access/nbtree/nbtree.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/nbtree.h"
#include "access/nbtxlog.h"
#include "access/relscan.h"
#include "access/xlog.h"
#include "commands/progress.h"
#include "commands/vacuum.h"
#include "miscadmin.h"
#include "nodes/execnodes.h"
#include "pgstat.h"
#include "postmaster/autovacuum.h"
#include "storage/condition_variable.h"
#include "storage/indexfsm.h"
#include "storage/ipc.h"
#include "storage/lmgr.h"
#include "storage/smgr.h"
#include "utils/builtins.h"
#include "utils/index_selfuncs.h"
#include "utils/memutils.h"
#include "utils/guc.h"
#include "catalog/indexing.h"
#include "catalog/pg_namespace.h"
/* Working state needed by btvacuumpage */
typedef struct
{
IndexVacuumInfo *info;
IndexBulkDeleteResult *stats;
IndexBulkDeleteCallback callback;
void *callback_state;
BTCycleId cycleid;
BlockNumber lastBlockVacuumed; /* highest blkno actually vacuumed */
BlockNumber lastBlockLocked; /* highest blkno we've cleanup-locked */
BlockNumber totFreePages; /* true total # of free pages */
TransactionId oldestBtpoXact;
MemoryContext pagedelcontext;
} BTVacState;
/*
* BTPARALLEL_NOT_INITIALIZED indicates that the scan has not started.
*
* BTPARALLEL_ADVANCING indicates that some process is advancing the scan to
* a new page; others must wait.
*
* BTPARALLEL_IDLE indicates that no backend is currently advancing the scan
* to a new page; some process can start doing that.
*
* BTPARALLEL_DONE indicates that the scan is complete (including error exit).
* We reach this state once for every distinct combination of array keys.
*/
typedef enum
{
BTPARALLEL_NOT_INITIALIZED,
BTPARALLEL_ADVANCING,
BTPARALLEL_IDLE,
BTPARALLEL_DONE
} BTPS_State;
/*
* BTParallelScanDescData contains btree specific shared information required
* for parallel scan.
*/
typedef struct BTParallelScanDescData
{
BlockNumber btps_scanPage; /* latest or next page to be scanned */
BTPS_State btps_pageStatus; /* indicates whether next page is
* available for scan. see above for
* possible states of parallel scan. */
int btps_arrayKeyCount; /* count indicating number of array scan
* keys processed by parallel scan */
slock_t btps_mutex; /* protects above variables */
ConditionVariable btps_cv; /* used to synchronize parallel scan */
} BTParallelScanDescData;
typedef struct BTParallelScanDescData *BTParallelScanDesc;
static void btvacuumscan(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
IndexBulkDeleteCallback callback, void *callback_state,
BTCycleId cycleid, TransactionId *oldestBtpoXact);
static void btvacuumpage(BTVacState *vstate, BlockNumber blkno,
BlockNumber orig_blkno);
/*
* Btree handler function: return IndexAmRoutine with access method parameters
* and callbacks.
*/
Datum
bthandler(PG_FUNCTION_ARGS)
{
IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
amroutine->amstrategies = BTMaxStrategyNumber;
amroutine->amsupport = BTNProcs;
amroutine->amcanorder = true;
amroutine->amcanorderbyop = false;
amroutine->amcanbackward = true;
amroutine->amcanunique = true;
amroutine->amcanmulticol = true;
amroutine->amoptionalkey = true;
amroutine->amsearcharray = true;
amroutine->amsearchnulls = true;
amroutine->amstorage = false;
amroutine->amclusterable = true;
amroutine->ampredlocks = true;
amroutine->amcanparallel = true;
amroutine->amcaninclude = true;
amroutine->amkeytype = InvalidOid;
amroutine->ambuild = btbuild;
amroutine->ambuildempty = btbuildempty;
amroutine->aminsert = btinsert;
amroutine->ambulkdelete = btbulkdelete;
amroutine->amvacuumcleanup = btvacuumcleanup;
amroutine->amcanreturn = btcanreturn;
amroutine->amcostestimate = btcostestimate;
amroutine->amoptions = btoptions;
amroutine->amproperty = btproperty;
amroutine->ambuildphasename = btbuildphasename;
amroutine->amvalidate = btvalidate;
amroutine->ambeginscan = btbeginscan;
amroutine->amrescan = btrescan;
amroutine->amgettuple = btgettuple;
amroutine->amgetbitmap = btgetbitmap;
amroutine->amendscan = btendscan;
amroutine->ammarkpos = btmarkpos;
amroutine->amrestrpos = btrestrpos;
amroutine->amestimateparallelscan = btestimateparallelscan;
amroutine->aminitparallelscan = btinitparallelscan;
amroutine->amparallelrescan = btparallelrescan;
PG_RETURN_POINTER(amroutine);
}
/*
* btbuildempty() -- build an empty btree index in the initialization fork
*/
void
btbuildempty(Relation index)
{
Page metapage;
/* Construct metapage. */
metapage = (Page) palloc(BLCKSZ);
_bt_initmetapage(metapage, P_NONE, 0);
/*
* Write the page and log it. It might seem that an immediate sync would
* be sufficient to guarantee that the file exists on disk, but recovery
* itself might remove it while replaying, for example, an
* XLOG_DBASE_CREATE or XLOG_TBLSPC_CREATE record. Therefore, we need
* this even when wal_level=minimal.
*/
PageSetChecksumInplace(metapage, BTREE_METAPAGE);
smgrwrite(index->rd_smgr, INIT_FORKNUM, BTREE_METAPAGE,
(char *) metapage, true);
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
BTREE_METAPAGE, metapage, true);
/*
* An immediate sync is required even if we xlog'd the page, because the
* write did not go through shared_buffers and therefore a concurrent
* checkpoint may have moved the redo pointer past our xlog record.
*/
smgrimmedsync(index->rd_smgr, INIT_FORKNUM);
}
/*
* For a newly inserted heap tid, check if an entry with this tid
* already exists in a unique index. If it does, abort the inserting
* transaction.
*/
static void
_bt_validate_tid(Relation irel, ItemPointer h_tid)
{
BlockNumber blkno;
BlockNumber num_pages;
Buffer buf;
Page page;
BTPageOpaque opaque;
IndexTuple itup;
OffsetNumber maxoff,
minoff,
offnum;
elog(DEBUG1, "validating tid (%d,%d) for index (%s)",
ItemPointerGetBlockNumber(h_tid), ItemPointerGetOffsetNumber(h_tid),
RelationGetRelationName(irel));
blkno = BTREE_METAPAGE + 1;
num_pages = RelationGetNumberOfBlocks(irel);
for (; blkno < num_pages; blkno++)
{
buf = ReadBuffer(irel, blkno);
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (!PageIsNew(page))
_bt_checkpage(irel, buf);
if (P_ISLEAF(opaque))
{
minoff = P_FIRSTDATAKEY(opaque);
maxoff = PageGetMaxOffsetNumber(page);
for (offnum = minoff;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
itup = (IndexTuple) PageGetItem(page,
PageGetItemId(page, offnum));
if (ItemPointerEquals(&itup->t_tid, h_tid))
{
Form_pg_attribute key_att = TupleDescAttr(RelationGetDescr(irel), 0);
Oid key = InvalidOid;
bool isnull;
if (key_att->atttypid == OIDOID)
{
key = DatumGetInt32(
index_getattr(itup, 1, RelationGetDescr(irel), &isnull));
elog(ERROR, "found tid (%d,%d), %s (%d) already in index (%s)",
ItemPointerGetBlockNumber(h_tid), ItemPointerGetOffsetNumber(h_tid),
NameStr(key_att->attname), key, RelationGetRelationName(irel));
}
else
{
elog(ERROR, "found tid (%d,%d) already in index (%s)",
ItemPointerGetBlockNumber(h_tid), ItemPointerGetOffsetNumber(h_tid),
RelationGetRelationName(irel));
}
}
}
}
ReleaseBuffer(buf);
}
}
/*
* btinsert() -- insert an index tuple into a btree.
*
* Descend the tree recursively, find the appropriate location for our
* new tuple, and put it there.
*/
bool
btinsert(Relation rel, Datum *values, bool *isnull,
ItemPointer ht_ctid, Relation heapRel,
IndexUniqueCheck checkUnique,
IndexInfo *indexInfo)
{
bool result;
IndexTuple itup;
if (checkUnique && (
(gp_indexcheck_insert == INDEX_CHECK_ALL && RelationIsHeap(heapRel)) ||
(gp_indexcheck_insert == INDEX_CHECK_SYSTEM &&
PG_CATALOG_NAMESPACE == RelationGetNamespace(heapRel))))
{
_bt_validate_tid(rel, ht_ctid);
}
/* generate an index tuple */
itup = index_form_tuple(RelationGetDescr(rel), values, isnull);
itup->t_tid = *ht_ctid;
result = _bt_doinsert(rel, itup, checkUnique, heapRel);
pfree(itup);
return result;
}
/*
* btgettuple() -- Get the next tuple in the scan.
*/
bool
btgettuple(IndexScanDesc scan, ScanDirection dir)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
bool res;
/* btree indexes are never lossy */
scan->xs_recheck = false;
/*
* If we have any array keys, initialize them during first call for a
* scan. We can't do this in btrescan because we don't know the scan
* direction at that time.
*/
if (so->numArrayKeys && !BTScanPosIsValid(so->currPos))
{
/* punt if we have any unsatisfiable array keys */
if (so->numArrayKeys < 0)
return false;
_bt_start_array_keys(scan, dir);
}
/* This loop handles advancing to the next array elements, if any */
do
{
/*
* If we've already initialized this scan, we can just advance it in
* the appropriate direction. If we haven't done so yet, we call
* _bt_first() to get the first item in the scan.
*/
if (!BTScanPosIsValid(so->currPos))
res = _bt_first(scan, dir);
else
{
/*
* Check to see if we should kill the previously-fetched tuple.
*/
if (scan->kill_prior_tuple)
{
/*
* Yes, remember it for later. (We'll deal with all such
* tuples at once right before leaving the index page.) The
* test for numKilled overrun is not just paranoia: if the
* caller reverses direction in the indexscan then the same
* item might get entered multiple times. It's not worth
* trying to optimize that, so we don't detect it, but instead
* just forget any excess entries.
*/
if (so->killedItems == NULL)
so->killedItems = (int *)
palloc(MaxIndexTuplesPerPage * sizeof(int));
if (so->numKilled < MaxIndexTuplesPerPage)
so->killedItems[so->numKilled++] = so->currPos.itemIndex;
}
/*
* Now continue the scan.
*/
res = _bt_next(scan, dir);
}
/* If we have a tuple, return it ... */
if (res)
break;
/* ... otherwise see if we have more array keys to deal with */
} while (so->numArrayKeys && _bt_advance_array_keys(scan, dir));
return res;
}
/*
* btgetbitmap() -- construct a TIDBitmap.
*/
int64
btgetbitmap(IndexScanDesc scan, Node **bmNodeP)
{
TIDBitmap *tbm;
BTScanOpaque so = (BTScanOpaque) scan->opaque;
int64 ntids = 0;
ItemPointer heapTid;
/*
* GPDB specific code. Since GPDB also support StreamBitmap
* in bitmap index. So normally we need to create specific bitmap
* node in the amgetbitmap AM.
*/
Assert(bmNodeP);
if (*bmNodeP == NULL)
{
/* XXX should we use less than work_mem for this? */
tbm = tbm_create(work_mem * 1024L, NULL);
*bmNodeP = (Node *) tbm;
}
else if (!IsA(*bmNodeP, TIDBitmap))
elog(ERROR, "non btree bitmap");
else
tbm = (TIDBitmap *)*bmNodeP;
/*
* If we have any array keys, initialize them.
*/
if (so->numArrayKeys)
{
/* punt if we have any unsatisfiable array keys */
if (so->numArrayKeys < 0)
return ntids;
_bt_start_array_keys(scan, ForwardScanDirection);
}
/* This loop handles advancing to the next array elements, if any */
do
{
/* Fetch the first page & tuple */
if (_bt_first(scan, ForwardScanDirection))
{
/* Save tuple ID, and continue scanning */
heapTid = &scan->xs_heaptid;
tbm_add_tuples(tbm, heapTid, 1, false);
ntids++;
for (;;)
{
/*
* Advance to next tuple within page. This is the same as the
* easy case in _bt_next().
*/
if (++so->currPos.itemIndex > so->currPos.lastItem)
{
/* let _bt_next do the heavy lifting */
if (!_bt_next(scan, ForwardScanDirection))
break;
}
/* Save tuple ID, and continue scanning */
heapTid = &so->currPos.items[so->currPos.itemIndex].heapTid;
tbm_add_tuples(tbm, heapTid, 1, false);
ntids++;
}
}
/* Now see if we have more array keys to deal with */
} while (so->numArrayKeys && _bt_advance_array_keys(scan, ForwardScanDirection));
return ntids;
}
/*
* btbeginscan() -- start a scan on a btree index
*/
IndexScanDesc
btbeginscan(Relation rel, int nkeys, int norderbys)
{
IndexScanDesc scan;
BTScanOpaque so;
/* no order by operators allowed */
Assert(norderbys == 0);
/* get the scan */
scan = RelationGetIndexScan(rel, nkeys, norderbys);
/* allocate private workspace */
so = (BTScanOpaque) palloc(sizeof(BTScanOpaqueData));
BTScanPosInvalidate(so->currPos);
BTScanPosInvalidate(so->markPos);
if (scan->numberOfKeys > 0)
so->keyData = (ScanKey) palloc(scan->numberOfKeys * sizeof(ScanKeyData));
else
so->keyData = NULL;
so->arrayKeyData = NULL; /* assume no array keys for now */
so->numArrayKeys = 0;
so->arrayKeys = NULL;
so->arrayContext = NULL;
so->killedItems = NULL; /* until needed */
so->numKilled = 0;
/*
* We don't know yet whether the scan will be index-only, so we do not
* allocate the tuple workspace arrays until btrescan. However, we set up
* scan->xs_itupdesc whether we'll need it or not, since that's so cheap.
*/
so->currTuples = so->markTuples = NULL;
scan->xs_itupdesc = RelationGetDescr(rel);
scan->opaque = so;
return scan;
}
/*
* btrescan() -- rescan an index relation
*/
void
btrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
ScanKey orderbys, int norderbys)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
/* we aren't holding any read locks, but gotta drop the pins */
if (BTScanPosIsValid(so->currPos))
{
/* Before leaving current page, deal with any killed items */
if (so->numKilled > 0)
_bt_killitems(scan);
BTScanPosUnpinIfPinned(so->currPos);
BTScanPosInvalidate(so->currPos);
}
so->markItemIndex = -1;
so->arrayKeyCount = 0;
BTScanPosUnpinIfPinned(so->markPos);
BTScanPosInvalidate(so->markPos);
/*
* Allocate tuple workspace arrays, if needed for an index-only scan and
* not already done in a previous rescan call. To save on palloc
* overhead, both workspaces are allocated as one palloc block; only this
* function and btendscan know that.
*
* NOTE: this data structure also makes it safe to return data from a
* "name" column, even though btree name_ops uses an underlying storage
* datatype of cstring. The risk there is that "name" is supposed to be
* padded to NAMEDATALEN, but the actual index tuple is probably shorter.
* However, since we only return data out of tuples sitting in the
* currTuples array, a fetch of NAMEDATALEN bytes can at worst pull some
* data out of the markTuples array --- running off the end of memory for
* a SIGSEGV is not possible. Yeah, this is ugly as sin, but it beats
* adding special-case treatment for name_ops elsewhere.
*/
if (scan->xs_want_itup && so->currTuples == NULL)
{
so->currTuples = (char *) palloc(BLCKSZ * 2);
so->markTuples = so->currTuples + BLCKSZ;
}
/*
* Reset the scan keys. Note that keys ordering stuff moved to _bt_first.
* - vadim 05/05/97
*/
if (scankey && scan->numberOfKeys > 0)
memmove(scan->keyData,
scankey,
scan->numberOfKeys * sizeof(ScanKeyData));
so->numberOfKeys = 0; /* until _bt_preprocess_keys sets it */
/* If any keys are SK_SEARCHARRAY type, set up array-key info */
_bt_preprocess_array_keys(scan);
}
/*
* btendscan() -- close down a scan
*/
void
btendscan(IndexScanDesc scan)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
/* we aren't holding any read locks, but gotta drop the pins */
if (BTScanPosIsValid(so->currPos))
{
/* Before leaving current page, deal with any killed items */
if (so->numKilled > 0)
_bt_killitems(scan);
BTScanPosUnpinIfPinned(so->currPos);
}
so->markItemIndex = -1;
BTScanPosUnpinIfPinned(so->markPos);
/* No need to invalidate positions, the RAM is about to be freed. */
/* Release storage */
if (so->keyData != NULL)
pfree(so->keyData);
/* so->arrayKeyData and so->arrayKeys are in arrayContext */
if (so->arrayContext != NULL)
MemoryContextDelete(so->arrayContext);
if (so->killedItems != NULL)
pfree(so->killedItems);
if (so->currTuples != NULL)
pfree(so->currTuples);
/* so->markTuples should not be pfree'd, see btrescan */
pfree(so);
}
/*
* btmarkpos() -- save current scan position
*/
void
btmarkpos(IndexScanDesc scan)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
/* There may be an old mark with a pin (but no lock). */
BTScanPosUnpinIfPinned(so->markPos);
/*
* Just record the current itemIndex. If we later step to next page
* before releasing the marked position, _bt_steppage makes a full copy of
* the currPos struct in markPos. If (as often happens) the mark is moved
* before we leave the page, we don't have to do that work.
*/
if (BTScanPosIsValid(so->currPos))
so->markItemIndex = so->currPos.itemIndex;
else
{
BTScanPosInvalidate(so->markPos);
so->markItemIndex = -1;
}
/* Also record the current positions of any array keys */
if (so->numArrayKeys)
_bt_mark_array_keys(scan);
}
/*
* btrestrpos() -- restore scan to last saved position
*/
void
btrestrpos(IndexScanDesc scan)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
/* Restore the marked positions of any array keys */
if (so->numArrayKeys)
_bt_restore_array_keys(scan);
if (so->markItemIndex >= 0)
{
/*
* The scan has never moved to a new page since the last mark. Just
* restore the itemIndex.
*
* NB: In this case we can't count on anything in so->markPos to be
* accurate.
*/
so->currPos.itemIndex = so->markItemIndex;
}
else
{
/*
* The scan moved to a new page after last mark or restore, and we are
* now restoring to the marked page. We aren't holding any read
* locks, but if we're still holding the pin for the current position,
* we must drop it.
*/
if (BTScanPosIsValid(so->currPos))
{
/* Before leaving current page, deal with any killed items */
if (so->numKilled > 0)
_bt_killitems(scan);
BTScanPosUnpinIfPinned(so->currPos);
}
if (BTScanPosIsValid(so->markPos))
{
/* bump pin on mark buffer for assignment to current buffer */
if (BTScanPosIsPinned(so->markPos))
IncrBufferRefCount(so->markPos.buf);
memcpy(&so->currPos, &so->markPos,
offsetof(BTScanPosData, items[1]) +
so->markPos.lastItem * sizeof(BTScanPosItem));
if (so->currTuples)
memcpy(so->currTuples, so->markTuples,
so->markPos.nextTupleOffset);
}
else
BTScanPosInvalidate(so->currPos);
}
}
/*
* btestimateparallelscan -- estimate storage for BTParallelScanDescData
*/
Size
btestimateparallelscan(void)
{
return sizeof(BTParallelScanDescData);
}
/*
* btinitparallelscan -- initialize BTParallelScanDesc for parallel btree scan
*/
void
btinitparallelscan(void *target)
{
BTParallelScanDesc bt_target = (BTParallelScanDesc) target;
SpinLockInit(&bt_target->btps_mutex);
bt_target->btps_scanPage = InvalidBlockNumber;
bt_target->btps_pageStatus = BTPARALLEL_NOT_INITIALIZED;
bt_target->btps_arrayKeyCount = 0;
ConditionVariableInit(&bt_target->btps_cv);
}
/*
* btparallelrescan() -- reset parallel scan
*/
void
btparallelrescan(IndexScanDesc scan)
{
BTParallelScanDesc btscan;
ParallelIndexScanDesc parallel_scan = scan->parallel_scan;
Assert(parallel_scan);
btscan = (BTParallelScanDesc) OffsetToPointer((void *) parallel_scan,
parallel_scan->ps_offset);
/*
* In theory, we don't need to acquire the spinlock here, because there
* shouldn't be any other workers running at this point, but we do so for
* consistency.
*/
SpinLockAcquire(&btscan->btps_mutex);
btscan->btps_scanPage = InvalidBlockNumber;
btscan->btps_pageStatus = BTPARALLEL_NOT_INITIALIZED;
btscan->btps_arrayKeyCount = 0;
SpinLockRelease(&btscan->btps_mutex);
}
/*
* _bt_parallel_seize() -- Begin the process of advancing the scan to a new
* page. Other scans must wait until we call _bt_parallel_release()
* or _bt_parallel_done().
*
* The return value is true if we successfully seized the scan and false
* if we did not. The latter case occurs if no pages remain for the current
* set of scankeys.
*
* If the return value is true, *pageno returns the next or current page
* of the scan (depending on the scan direction). An invalid block number
* means the scan hasn't yet started, and P_NONE means we've reached the end.
* The first time a participating process reaches the last page, it will return
* true and set *pageno to P_NONE; after that, further attempts to seize the
* scan will return false.
*
* Callers should ignore the value of pageno if the return value is false.
*/
bool
_bt_parallel_seize(IndexScanDesc scan, BlockNumber *pageno)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
BTPS_State pageStatus;
bool exit_loop = false;
bool status = true;
ParallelIndexScanDesc parallel_scan = scan->parallel_scan;
BTParallelScanDesc btscan;
*pageno = P_NONE;
btscan = (BTParallelScanDesc) OffsetToPointer((void *) parallel_scan,
parallel_scan->ps_offset);
while (1)
{
SpinLockAcquire(&btscan->btps_mutex);
pageStatus = btscan->btps_pageStatus;
if (so->arrayKeyCount < btscan->btps_arrayKeyCount)
{
/* Parallel scan has already advanced to a new set of scankeys. */
status = false;
}
else if (pageStatus == BTPARALLEL_DONE)
{
/*
* We're done with this set of scankeys. This may be the end, or
* there could be more sets to try.
*/
status = false;
}
else if (pageStatus != BTPARALLEL_ADVANCING)
{
/*
* We have successfully seized control of the scan for the purpose
* of advancing it to a new page!
*/
btscan->btps_pageStatus = BTPARALLEL_ADVANCING;
*pageno = btscan->btps_scanPage;
exit_loop = true;
}
SpinLockRelease(&btscan->btps_mutex);
if (exit_loop || !status)
break;
ConditionVariableSleep(&btscan->btps_cv, WAIT_EVENT_BTREE_PAGE);
}
ConditionVariableCancelSleep();
return status;
}
/*
* _bt_parallel_release() -- Complete the process of advancing the scan to a
* new page. We now have the new value btps_scanPage; some other backend
* can now begin advancing the scan.
*/
void
_bt_parallel_release(IndexScanDesc scan, BlockNumber scan_page)
{
ParallelIndexScanDesc parallel_scan = scan->parallel_scan;
BTParallelScanDesc btscan;
btscan = (BTParallelScanDesc) OffsetToPointer((void *) parallel_scan,
parallel_scan->ps_offset);
SpinLockAcquire(&btscan->btps_mutex);
btscan->btps_scanPage = scan_page;
btscan->btps_pageStatus = BTPARALLEL_IDLE;
SpinLockRelease(&btscan->btps_mutex);
ConditionVariableSignal(&btscan->btps_cv);
}
/*
* _bt_parallel_done() -- Mark the parallel scan as complete.
*
* When there are no pages left to scan, this function should be called to
* notify other workers. Otherwise, they might wait forever for the scan to
* advance to the next page.
*/
void
_bt_parallel_done(IndexScanDesc scan)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
ParallelIndexScanDesc parallel_scan = scan->parallel_scan;
BTParallelScanDesc btscan;
bool status_changed = false;
/* Do nothing, for non-parallel scans */
if (parallel_scan == NULL)
return;
btscan = (BTParallelScanDesc) OffsetToPointer((void *) parallel_scan,
parallel_scan->ps_offset);
/*
* Mark the parallel scan as done for this combination of scan keys,
* unless some other process already did so. See also
* _bt_advance_array_keys.
*/
SpinLockAcquire(&btscan->btps_mutex);
if (so->arrayKeyCount >= btscan->btps_arrayKeyCount &&
btscan->btps_pageStatus != BTPARALLEL_DONE)
{
btscan->btps_pageStatus = BTPARALLEL_DONE;
status_changed = true;
}
SpinLockRelease(&btscan->btps_mutex);
/* wake up all the workers associated with this parallel scan */
if (status_changed)
ConditionVariableBroadcast(&btscan->btps_cv);
}
/*
* _bt_parallel_advance_array_keys() -- Advances the parallel scan for array
* keys.
*
* Updates the count of array keys processed for both local and parallel
* scans.
*/
void
_bt_parallel_advance_array_keys(IndexScanDesc scan)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
ParallelIndexScanDesc parallel_scan = scan->parallel_scan;
BTParallelScanDesc btscan;
btscan = (BTParallelScanDesc) OffsetToPointer((void *) parallel_scan,
parallel_scan->ps_offset);
so->arrayKeyCount++;
SpinLockAcquire(&btscan->btps_mutex);
if (btscan->btps_pageStatus == BTPARALLEL_DONE)
{
btscan->btps_scanPage = InvalidBlockNumber;
btscan->btps_pageStatus = BTPARALLEL_NOT_INITIALIZED;
btscan->btps_arrayKeyCount++;
}
SpinLockRelease(&btscan->btps_mutex);
}
/*
* _bt_vacuum_needs_cleanup() -- Checks if index needs cleanup assuming that
* btbulkdelete() wasn't called.
*/
static bool
_bt_vacuum_needs_cleanup(IndexVacuumInfo *info)
{
Buffer metabuf;
Page metapg;
BTMetaPageData *metad;
bool result = false;
metabuf = _bt_getbuf(info->index, BTREE_METAPAGE, BT_READ);
metapg = BufferGetPage(metabuf);
metad = BTPageGetMeta(metapg);
if (metad->btm_version < BTREE_NOVAC_VERSION)
{
/*
* Do cleanup if metapage needs upgrade, because we don't have
* cleanup-related meta-information yet.
*/
result = true;
}
else if (TransactionIdIsValid(metad->btm_oldest_btpo_xact) &&
TransactionIdPrecedes(metad->btm_oldest_btpo_xact,
RecentGlobalXmin))
{
/*
* If oldest btpo.xact in the deleted pages is older than
* RecentGlobalXmin, then at least one deleted page can be recycled.
*/
result = true;
}
else
{
StdRdOptions *relopts;
float8 cleanup_scale_factor;
float8 prev_num_heap_tuples;
/*
* If table receives enough insertions and no cleanup was performed,
* then index would appear have stale statistics. If scale factor is
* set, we avoid that by performing cleanup if the number of inserted
* tuples exceeds vacuum_cleanup_index_scale_factor fraction of
* original tuples count.
*/
relopts = (StdRdOptions *) info->index->rd_options;
cleanup_scale_factor = (relopts &&
relopts->vacuum_cleanup_index_scale_factor >= 0)
? relopts->vacuum_cleanup_index_scale_factor
: vacuum_cleanup_index_scale_factor;
prev_num_heap_tuples = metad->btm_last_cleanup_num_heap_tuples;
if (cleanup_scale_factor <= 0 ||
prev_num_heap_tuples <= 0 ||
(info->num_heap_tuples - prev_num_heap_tuples) /
prev_num_heap_tuples >= cleanup_scale_factor)
result = true;
}
_bt_relbuf(info->index, metabuf);
return result;
}
/*
* Bulk deletion of all index entries pointing to a set of heap tuples.
* The set of target tuples is specified via a callback routine that tells
* whether any given heap tuple (identified by ItemPointer) is being deleted.
*
* Result: a palloc'd struct containing statistical info for VACUUM displays.
*/
IndexBulkDeleteResult *
btbulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
IndexBulkDeleteCallback callback, void *callback_state)
{
Relation rel = info->index;
BTCycleId cycleid;
/* allocate stats if first time through, else re-use existing struct */
if (stats == NULL)
stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
/* Establish the vacuum cycle ID to use for this scan */
/* The ENSURE stuff ensures we clean up shared memory on failure */
PG_ENSURE_ERROR_CLEANUP(_bt_end_vacuum_callback, PointerGetDatum(rel));
{
TransactionId oldestBtpoXact;
cycleid = _bt_start_vacuum(rel);
btvacuumscan(info, stats, callback, callback_state, cycleid,
&oldestBtpoXact);
/*
* Update cleanup-related information in metapage. This information is
* used only for cleanup but keeping them up to date can avoid
* unnecessary cleanup even after bulkdelete.
*/
_bt_update_meta_cleanup_info(info->index, oldestBtpoXact,
info->num_heap_tuples);
}
PG_END_ENSURE_ERROR_CLEANUP(_bt_end_vacuum_callback, PointerGetDatum(rel));
_bt_end_vacuum(rel);
return stats;
}
/*
* Post-VACUUM cleanup.
*
* Result: a palloc'd struct containing statistical info for VACUUM displays.
*/
IndexBulkDeleteResult *
btvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
{
/* No-op in ANALYZE ONLY mode */
if (info->analyze_only)
return stats;
/*
* If btbulkdelete was called, we need not do anything, just return the
* stats from the latest btbulkdelete call. If it wasn't called, we might
* still need to do a pass over the index, to recycle any newly-recyclable
* pages or to obtain index statistics. _bt_vacuum_needs_cleanup
* determines if either are needed.
*
* Since we aren't going to actually delete any leaf items, there's no
* need to go through all the vacuum-cycle-ID pushups.
*/
if (stats == NULL)
{
TransactionId oldestBtpoXact;
/* Check if we need a cleanup */
if (!_bt_vacuum_needs_cleanup(info))
return NULL;
stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
btvacuumscan(info, stats, NULL, NULL, 0, &oldestBtpoXact);
/* Update cleanup-related information in the metapage */
_bt_update_meta_cleanup_info(info->index, oldestBtpoXact,
info->num_heap_tuples);
}
/*
* It's quite possible for us to be fooled by concurrent page splits into
* double-counting some index tuples, so disbelieve any total that exceeds
* the underlying heap's count ... if we know that accurately. Otherwise
* this might just make matters worse.
*/
if (!info->estimated_count)
{
if (stats->num_index_tuples > info->num_heap_tuples)
stats->num_index_tuples = info->num_heap_tuples;
}
return stats;
}
/*
* btvacuumscan --- scan the index for VACUUMing purposes
*
* This combines the functions of looking for leaf tuples that are deletable
* according to the vacuum callback, looking for empty pages that can be
* deleted, and looking for old deleted pages that can be recycled. Both
* btbulkdelete and btvacuumcleanup invoke this (the latter only if no
* btbulkdelete call occurred).
*
* The caller is responsible for initially allocating/zeroing a stats struct
* and for obtaining a vacuum cycle ID if necessary.
*/
static void
btvacuumscan(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
IndexBulkDeleteCallback callback, void *callback_state,
BTCycleId cycleid, TransactionId *oldestBtpoXact)
{
Relation rel = info->index;
BTVacState vstate;
BlockNumber num_pages;
BlockNumber blkno;
bool needLock;
/*
* Reset counts that will be incremented during the scan; needed in case
* of multiple scans during a single VACUUM command
*/
stats->estimated_count = false;
stats->num_index_tuples = 0;
stats->pages_deleted = 0;
/* Set up info to pass down to btvacuumpage */
vstate.info = info;
vstate.stats = stats;
vstate.callback = callback;
vstate.callback_state = callback_state;
vstate.cycleid = cycleid;
vstate.lastBlockVacuumed = BTREE_METAPAGE; /* Initialise at first block */
vstate.lastBlockLocked = BTREE_METAPAGE;
vstate.totFreePages = 0;
vstate.oldestBtpoXact = InvalidTransactionId;
/* Create a temporary memory context to run _bt_pagedel in */
vstate.pagedelcontext = AllocSetContextCreate(CurrentMemoryContext,
"_bt_pagedel",
ALLOCSET_DEFAULT_SIZES);
/*
* The outer loop iterates over all index pages except the metapage, in
* physical order (we hope the kernel will cooperate in providing
* read-ahead for speed). It is critical that we visit all leaf pages,
* including ones added after we start the scan, else we might fail to
* delete some deletable tuples. Hence, we must repeatedly check the
* relation length. We must acquire the relation-extension lock while
* doing so to avoid a race condition: if someone else is extending the
* relation, there is a window where bufmgr/smgr have created a new
* all-zero page but it hasn't yet been write-locked by _bt_getbuf(). If
* we manage to scan such a page here, we'll improperly assume it can be
* recycled. Taking the lock synchronizes things enough to prevent a
* problem: either num_pages won't include the new page, or _bt_getbuf
* already has write lock on the buffer and it will be fully initialized
* before we can examine it. (See also vacuumlazy.c, which has the same
* issue.) Also, we need not worry if a page is added immediately after
* we look; the page splitting code already has write-lock on the left
* page before it adds a right page, so we must already have processed any
* tuples due to be moved into such a page.
*
* We can skip locking for new or temp relations, however, since no one
* else could be accessing them.
*/
needLock = !RELATION_IS_LOCAL(rel);
blkno = BTREE_METAPAGE + 1;
for (;;)
{
/* Get the current relation length */
if (needLock)
LockRelationForExtension(rel, ExclusiveLock);
num_pages = RelationGetNumberOfBlocks(rel);
if (needLock)
UnlockRelationForExtension(rel, ExclusiveLock);
if (info->report_progress)
pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_TOTAL,
num_pages);
/* Quit if we've scanned the whole relation */
if (blkno >= num_pages)
break;
/* Iterate over pages, then loop back to recheck length */
for (; blkno < num_pages; blkno++)
{
btvacuumpage(&vstate, blkno, blkno);
if (info->report_progress)
pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_DONE,
blkno);
}
}
/*
* Check to see if we need to issue one final WAL record for this index,
* which may be needed for correctness on a hot standby node when non-MVCC
* index scans could take place.
*
* If the WAL is replayed in hot standby, the replay process needs to get
* cleanup locks on all index leaf pages, just as we've been doing here.
* However, we won't issue any WAL records about pages that have no items
* to be deleted. For pages between pages we've vacuumed, the replay code
* will take locks under the direction of the lastBlockVacuumed fields in
* the XLOG_BTREE_VACUUM WAL records. To cover pages after the last one
* we vacuum, we need to issue a dummy XLOG_BTREE_VACUUM WAL record
* against the last leaf page in the index, if that one wasn't vacuumed.
*/
if (XLogStandbyInfoActive() &&
vstate.lastBlockVacuumed < vstate.lastBlockLocked)
{
Buffer buf;
/*
* The page should be valid, but we can't use _bt_getbuf() because we
* want to use a nondefault buffer access strategy. Since we aren't
* going to delete any items, getting cleanup lock again is probably
* overkill, but for consistency do that anyway.
*/
buf = ReadBufferExtended(rel, MAIN_FORKNUM, vstate.lastBlockLocked,
RBM_NORMAL, info->strategy);
LockBufferForCleanup(buf);
_bt_checkpage(rel, buf);
_bt_delitems_vacuum(rel, buf, NULL, 0, vstate.lastBlockVacuumed);
_bt_relbuf(rel, buf);
}
MemoryContextDelete(vstate.pagedelcontext);
/*
* If we found any recyclable pages (and recorded them in the FSM), then
* forcibly update the upper-level FSM pages to ensure that searchers can
* find them. It's possible that the pages were also found during
* previous scans and so this is a waste of time, but it's cheap enough
* relative to scanning the index that it shouldn't matter much, and
* making sure that free pages are available sooner not later seems
* worthwhile.
*
* Note that if no recyclable pages exist, we don't bother vacuuming the
* FSM at all.
*/
if (vstate.totFreePages > 0)
IndexFreeSpaceMapVacuum(rel);
/* update statistics */
stats->num_pages = num_pages;
stats->pages_free = vstate.totFreePages;
if (oldestBtpoXact)
*oldestBtpoXact = vstate.oldestBtpoXact;
}
/*
* btvacuumpage --- VACUUM one page
*
* This processes a single page for btvacuumscan(). In some cases we
* must go back and re-examine previously-scanned pages; this routine
* recurses when necessary to handle that case.
*
* blkno is the page to process. orig_blkno is the highest block number
* reached by the outer btvacuumscan loop (the same as blkno, unless we
* are recursing to re-examine a previous page).
*/
static void
btvacuumpage(BTVacState *vstate, BlockNumber blkno, BlockNumber orig_blkno)
{
IndexVacuumInfo *info = vstate->info;
IndexBulkDeleteResult *stats = vstate->stats;
IndexBulkDeleteCallback callback = vstate->callback;
void *callback_state = vstate->callback_state;
Relation rel = info->index;
bool delete_now;
BlockNumber recurse_to;
Buffer buf;
Page page;
BTPageOpaque opaque = NULL;
restart:
delete_now = false;
recurse_to = P_NONE;
/* call vacuum_delay_point while not holding any buffer lock */
vacuum_delay_point();
/*
* We can't use _bt_getbuf() here because it always applies
* _bt_checkpage(), which will barf on an all-zero page. We want to
* recycle all-zero pages, not fail. Also, we want to use a nondefault
* buffer access strategy.
*/
buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
info->strategy);
LockBuffer(buf, BT_READ);
page = BufferGetPage(buf);
if (!PageIsNew(page))
{
_bt_checkpage(rel, buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
}
/*
* If we are recursing, the only case we want to do anything with is a
* live leaf page having the current vacuum cycle ID. Any other state
* implies we already saw the page (eg, deleted it as being empty).
*/
if (blkno != orig_blkno)
{
if (_bt_page_recyclable(page) ||
P_IGNORE(opaque) ||
!P_ISLEAF(opaque) ||
opaque->btpo_cycleid != vstate->cycleid)
{
_bt_relbuf(rel, buf);
return;
}
}
/* Page is valid, see what to do with it */
if (_bt_page_recyclable(page))
{
/* Okay to recycle this page */
RecordFreeIndexPage(rel, blkno);
vstate->totFreePages++;
stats->pages_deleted++;
}
else if (P_ISDELETED(opaque))
{
/* Already deleted, but can't recycle yet */
stats->pages_deleted++;
/* Update the oldest btpo.xact */
if (!TransactionIdIsValid(vstate->oldestBtpoXact) ||
TransactionIdPrecedes(opaque->btpo.xact, vstate->oldestBtpoXact))
vstate->oldestBtpoXact = opaque->btpo.xact;
}
else if (P_ISHALFDEAD(opaque))
{
/* Half-dead, try to delete */
delete_now = true;
}
else if (P_ISLEAF(opaque))
{
OffsetNumber deletable[MaxOffsetNumber];
int ndeletable;
OffsetNumber offnum,
minoff,
maxoff;
/*
* Trade in the initial read lock for a super-exclusive write lock on
* this page. We must get such a lock on every leaf page over the
* course of the vacuum scan, whether or not it actually contains any
* deletable tuples --- see nbtree/README.
*/
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
LockBufferForCleanup(buf);
/*
* Remember highest leaf page number we've taken cleanup lock on; see
* notes in btvacuumscan
*/
if (blkno > vstate->lastBlockLocked)
vstate->lastBlockLocked = blkno;
/*
* Check whether we need to recurse back to earlier pages. What we
* are concerned about is a page split that happened since we started
* the vacuum scan. If the split moved some tuples to a lower page
* then we might have missed 'em. If so, set up for tail recursion.
* (Must do this before possibly clearing btpo_cycleid below!)
*/
if (vstate->cycleid != 0 &&
opaque->btpo_cycleid == vstate->cycleid &&
!(opaque->btpo_flags & BTP_SPLIT_END) &&
!P_RIGHTMOST(opaque) &&
opaque->btpo_next < orig_blkno)
recurse_to = opaque->btpo_next;
/*
* Scan over all items to see which ones need deleted according to the
* callback function.
*/
ndeletable = 0;
minoff = P_FIRSTDATAKEY(opaque);
maxoff = PageGetMaxOffsetNumber(page);
if (callback)
{
for (offnum = minoff;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
IndexTuple itup;
ItemPointer htup;
itup = (IndexTuple) PageGetItem(page,
PageGetItemId(page, offnum));
htup = &(itup->t_tid);
/*
* During Hot Standby we currently assume that
* XLOG_BTREE_VACUUM records do not produce conflicts. That is
* only true as long as the callback function depends only
* upon whether the index tuple refers to heap tuples removed
* in the initial heap scan. When vacuum starts it derives a
* value of OldestXmin. Backends taking later snapshots could
* have a RecentGlobalXmin with a later xid than the vacuum's
* OldestXmin, so it is possible that row versions deleted
* after OldestXmin could be marked as killed by other
* backends. The callback function *could* look at the index
* tuple state in isolation and decide to delete the index
* tuple, though currently it does not. If it ever did, we
* would need to reconsider whether XLOG_BTREE_VACUUM records
* should cause conflicts. If they did cause conflicts they
* would be fairly harsh conflicts, since we haven't yet
* worked out a way to pass a useful value for
* latestRemovedXid on the XLOG_BTREE_VACUUM records. This
* applies to *any* type of index that marks index tuples as
* killed.
*/
if (callback(htup, callback_state))
deletable[ndeletable++] = offnum;
}
}
/*
* Apply any needed deletes. We issue just one _bt_delitems_vacuum()
* call per page, so as to minimize WAL traffic.
*/
if (ndeletable > 0)
{
/*
* Notice that the issued XLOG_BTREE_VACUUM WAL record includes
* all information to the replay code to allow it to get a cleanup
* lock on all pages between the previous lastBlockVacuumed and
* this page. This ensures that WAL replay locks all leaf pages at
* some point, which is important should non-MVCC scans be
* requested. This is currently unused on standby, but we record
* it anyway, so that the WAL contains the required information.
*
* Since we can visit leaf pages out-of-order when recursing,
* replay might end up locking such pages an extra time, but it
* doesn't seem worth the amount of bookkeeping it'd take to avoid
* that.
*/
_bt_delitems_vacuum(rel, buf, deletable, ndeletable,
vstate->lastBlockVacuumed);
/*
* Remember highest leaf page number we've issued a
* XLOG_BTREE_VACUUM WAL record for.
*/
if (blkno > vstate->lastBlockVacuumed)
vstate->lastBlockVacuumed = blkno;
stats->tuples_removed += ndeletable;
/* must recompute maxoff */
maxoff = PageGetMaxOffsetNumber(page);
}
else
{
/*
* If the page has been split during this vacuum cycle, it seems
* worth expending a write to clear btpo_cycleid even if we don't
* have any deletions to do. (If we do, _bt_delitems_vacuum takes
* care of this.) This ensures we won't process the page again.
*
* We treat this like a hint-bit update because there's no need to
* WAL-log it.
*/
if (vstate->cycleid != 0 &&
opaque->btpo_cycleid == vstate->cycleid)
{
opaque->btpo_cycleid = 0;
MarkBufferDirtyHint(buf, true);
}
}
/*
* If it's now empty, try to delete; else count the live tuples. We
* don't delete when recursing, though, to avoid putting entries into
* freePages out-of-order (doesn't seem worth any extra code to handle
* the case).
*/
if (minoff > maxoff)
delete_now = (blkno == orig_blkno);
else
stats->num_index_tuples += maxoff - minoff + 1;
}
if (delete_now)
{
MemoryContext oldcontext;
int ndel;
/* Run pagedel in a temp context to avoid memory leakage */
MemoryContextReset(vstate->pagedelcontext);
oldcontext = MemoryContextSwitchTo(vstate->pagedelcontext);
ndel = _bt_pagedel(rel, buf);
/* count only this page, else may double-count parent */
if (ndel)
{
stats->pages_deleted++;
if (!TransactionIdIsValid(vstate->oldestBtpoXact) ||
TransactionIdPrecedes(opaque->btpo.xact, vstate->oldestBtpoXact))
vstate->oldestBtpoXact = opaque->btpo.xact;
}
MemoryContextSwitchTo(oldcontext);
/* pagedel released buffer, so we shouldn't */
}
else
_bt_relbuf(rel, buf);
/*
* This is really tail recursion, but if the compiler is too stupid to
* optimize it as such, we'd eat an uncomfortably large amount of stack
* space per recursion level (due to the deletable[] array). A failure is
* improbable since the number of levels isn't likely to be large ... but
* just in case, let's hand-optimize into a loop.
*/
if (recurse_to != P_NONE)
{
blkno = recurse_to;
goto restart;
}
}
/*
* btcanreturn() -- Check whether btree indexes support index-only scans.
*
* btrees always do, so this is trivial.
*/
bool
btcanreturn(Relation index, int attno)
{
return true;
}
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