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Postgres FD Implementation
Commit 329a5322 authored by Teodor Sigaev's avatar Teodor Sigaev
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Fix infinite loop while checking of partial match in pending list. 

Improve comments. Now GIN-indexable operators should be strict.
Per Tom's questions/suggestions.
parent 27fbfd39
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Showing with 85 additions and 15 deletions
src/backend/access/gin/ginget.c
View file @ 329a5322
......@@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gin/ginget.c,v 1.24 2009/03/25 22:19:01 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/gin/ginget.c,v 1.25 2009/04/05 11:32:01 teodor Exp $
*-------------------------------------------------------------------------
*/
......@@ -618,6 +618,7 @@ entryGetItem(Relation index, GinScanEntry entry)
* Sets key->curItem to new found heap item pointer for one scan key
* Returns isFinished, ie TRUE means we did NOT get a new item pointer!
* Also, *keyrecheck is set true if recheck is needed for this scan key.
* Note: lossy page could be returned after items from the same page.
*/
static bool
keyGetItem(Relation index, GinState *ginstate, MemoryContext tempCtx,
......@@ -635,7 +636,10 @@ keyGetItem(Relation index, GinState *ginstate, MemoryContext tempCtx,
{
/*
* move forward from previously value and set new curItem, which is
* minimal from entries->curItems
* minimal from entries->curItems. Lossy page is encoded by ItemPointer
* with max value for offset (0xffff), so if there is an non-lossy entries
* on lossy page they will returned too and after that the whole page.
* That's not a problem for resulting tidbitmap.
*/
ItemPointerSetMax(&key->curItem);
for (i = 0; i < key->nentries; i++)
......@@ -646,7 +650,8 @@ keyGetItem(Relation index, GinState *ginstate, MemoryContext tempCtx,
{
/*
* Move forward only entries which was the least
* on previous call
* on previous call, key->entryRes[i] points that
* current entry was a result of loop/call.
*/
if (entry->isFinished == FALSE && entryGetItem(index, entry) == FALSE)
{
......@@ -671,11 +676,21 @@ keyGetItem(Relation index, GinState *ginstate, MemoryContext tempCtx,
}
/*
* Now key->curItem contains closest ItemPointer to previous result.
*
* if key->nentries == 1 then the consistentFn should always succeed,
* but we must call it anyway to find out the recheck status.
*/
/* setting up array for consistentFn */
/*----------
* entryRes array is used for:
* - as an argument for consistentFn
* - entry->curItem with corresponding key->entryRes[i] == false are
* greater than key->curItem, so next loop/call they should be
* renewed by entryGetItem(). So, we need to set up an array before
* checking of lossy page.
*----------
*/
for (i = 0; i < key->nentries; i++)
{
entry = key->scanEntry + i;
......@@ -719,7 +734,10 @@ keyGetItem(Relation index, GinState *ginstate, MemoryContext tempCtx,
/*
* Get ItemPointer of next heap row to be checked from pending list.
* Returns false if there are no more.
* Returns false if there are no more. On pages with several rows
* it returns each row separately, on page with part of heap row returns
* per page data. pos->firstOffset and pos->lastOffset points
* fraction of tuples for current heap row.
*
* The pendingBuffer is presumed pinned and share-locked on entry, and is
* pinned and share-locked on success exit. On failure exit it's released.
......@@ -787,6 +805,13 @@ scanGetCandidate(IndexScanDesc scan, pendingPosition *pos)
*/
pos->lastOffset = maxoff + 1;
}
/*
* Now pos->firstOffset points to the first tuple of current heap row,
* pos->lastOffset points to the first tuple of second heap row (or
* to the end of page)
*/
break;
}
}
......@@ -794,6 +819,12 @@ scanGetCandidate(IndexScanDesc scan, pendingPosition *pos)
return true;
}
/*
* Scan page from current tuple (off) up to the first event:
* - tuple's attribute number is not equal to entry's attrnum
* - reach of last tuple
* - match is found (then returns true)
*/
static bool
matchPartialInPendingList(GinState *ginstate, Page page,
OffsetNumber off, OffsetNumber maxoff,
......@@ -817,6 +848,13 @@ matchPartialInPendingList(GinState *ginstate, Page page,
datumExtracted[ off-1 ] = true;
}
/*----------
* Check of partial match.
* case cmp == 0 => match
* case cmp > 0 => not match and finish scan
* case cmp < 0 => not match and continue scan
*----------
*/
cmp = DatumGetInt32(FunctionCall4(&ginstate->comparePartialFn[attrnum],
value,
datum[off-1],
......@@ -826,6 +864,8 @@ matchPartialInPendingList(GinState *ginstate, Page page,
return true;
else if (cmp > 0)
return false;
off++;
}
return false;
......@@ -833,7 +873,7 @@ matchPartialInPendingList(GinState *ginstate, Page page,
/*
* Sets entryRes array for each key by looking at
* every entry per indexed value (row) in pending list.
* every entry per indexed value (heap's row) in pending list.
* returns true if at least one of datum was matched by key's entry
*
* The pendingBuffer is presumed pinned and share-locked on entry.
......@@ -878,9 +918,15 @@ collectDatumForItem(IndexScanDesc scan, pendingPosition *pos)
StopMiddle;
GinScanEntry entry = key->scanEntry + j;
/* already true - do not extra work */
if ( key->entryRes[j] )
continue;
/*
* Interested tuples are from pos->firstOffset to pos->lastOffset
* and they are ordered by (attnum, Datum) as it's done in entry tree
* So we could use binary search to prevent linear scanning
*/
while (StopLow < StopHigh)
{
StopMiddle = StopLow + ((StopHigh - StopLow) >> 1);
......@@ -908,6 +954,11 @@ collectDatumForItem(IndexScanDesc scan, pendingPosition *pos)
if ( res == 0 )
{
/*
* The exact match causes, so we just scan from
* current position to find a partial match.
* See comment above about tuple's ordering.
*/
if ( entry->isPartialMatch )
key->entryRes[j] =
matchPartialInPendingList(&so->ginstate,
......@@ -931,6 +982,12 @@ collectDatumForItem(IndexScanDesc scan, pendingPosition *pos)
}
if ( StopLow>=StopHigh && entry->isPartialMatch )
{
/*
* The exact match wasn't found, so we need to start
* scan from first tuple greater then current entry
* See comment above about tuple's ordering.
*/
key->entryRes[j] =
matchPartialInPendingList(&so->ginstate,
page, StopHigh,
......@@ -941,6 +998,7 @@ collectDatumForItem(IndexScanDesc scan, pendingPosition *pos)
datumExtracted,
entry->strategy,
entry->extra_data);
}
hasMatch |= key->entryRes[j];
}
......@@ -960,6 +1018,11 @@ collectDatumForItem(IndexScanDesc scan, pendingPosition *pos)
{
ItemPointerData item = pos->item;
/*
* need to get next portion of tuples of row containing
* on several pages
*/
if ( scanGetCandidate(scan, pos) == false || !ItemPointerEquals(&pos->item, &item) )
elog(ERROR,"Could not process tuple"); /* XXX should not be here ! */
}
......@@ -1004,19 +1067,23 @@ scanPendingInsert(IndexScanDesc scan, TIDBitmap *tbm, int64 *ntids)
UnlockReleaseBuffer( metabuffer );
/*
* loop for each heap row
* loop for each heap row. scanGetCandidate returns full row
* or row's tuples from first page.
*/
while( scanGetCandidate(scan, &pos) )
{
/*
* Check entries in rows and setup entryRes array
* Check entries in tuple and setup entryRes array
* If tuples of heap's row are placed on several pages
* collectDatumForItem will read all of that pages.
*/
if (!collectDatumForItem(scan, &pos))
continue;
/*
* check for consistent
* Matching of entries of one row is finished,
* so check row by consistent function.
*/
oldCtx = MemoryContextSwitchTo(so->tempCtx);
recheck = false;
......
src/backend/access/gin/ginscan.c
View file @ 329a5322
......@@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gin/ginscan.c,v 1.22 2009/03/25 22:19:01 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/gin/ginscan.c,v 1.23 2009/04/05 11:32:01 teodor Exp $
*-------------------------------------------------------------------------
*/
......@@ -175,12 +175,15 @@ newScanKey(IndexScanDesc scan)
bool *partial_matches = NULL;
Pointer *extra_data = NULL;
/* XXX can't we treat nulls by just setting isVoidRes? */
/* This would amount to assuming that all GIN operators are strict */
/*
* Assume, that GIN-indexable operators are strict, so
* nothing could be found
*/
if (skey->sk_flags & SK_ISNULL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("GIN indexes do not support NULL scan keys")));
{
so->isVoidRes = true;
break;
}
entryValues = (Datum *)
DatumGetPointer(FunctionCall5(&so->ginstate.extractQueryFn[skey->sk_attno - 1],
......
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