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Commit8bf7496

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Reduce the number of pallocs() in BRIN
Instead of allocating memory in brin_deform_tuple and brin_copy_tupleover and over during a scan, allow reuse of previously allocated memory.This is said to make for a measurable performance improvement.Author: Jinyu Zhang, Álvaro HerreraReviewed by: Tomas VondraDiscussion:https://postgr.es/m/495deb78.4186.1500dacaa63.Coremail.beijing_pg@163.com
1 parente8fdbd5 commit8bf7496

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5 files changed

+78
-42
lines changed

5 files changed

+78
-42
lines changed

‎contrib/pageinspect/brinfuncs.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -226,7 +226,8 @@ brin_page_items(PG_FUNCTION_ARGS)
226226
if (ItemIdIsUsed(itemId))
227227
{
228228
dtup=brin_deform_tuple(bdesc,
229-
(BrinTuple*)PageGetItem(page,itemId));
229+
(BrinTuple*)PageGetItem(page,itemId),
230+
NULL);
230231
attno=1;
231232
unusedItem= false;
232233
}

‎src/backend/access/brin/brin.c

Lines changed: 15 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -217,7 +217,7 @@ brininsert(Relation idxRel, Datum *values, bool *nulls,
217217
MemoryContextSwitchTo(tupcxt);
218218
}
219219

220-
dtup=brin_deform_tuple(bdesc,brtup);
220+
dtup=brin_deform_tuple(bdesc,brtup,NULL);
221221

222222
/*
223223
* Compare the key values of the new tuple to the stored index values;
@@ -268,7 +268,7 @@ brininsert(Relation idxRel, Datum *values, bool *nulls,
268268
* re-acquiring the lock.
269269
*/
270270
origsz=ItemIdGetLength(lp);
271-
origtup=brin_copy_tuple(brtup,origsz);
271+
origtup=brin_copy_tuple(brtup,origsz,NULL,NULL);
272272

273273
/*
274274
* Before releasing the lock, check if we can attempt a same-page
@@ -363,6 +363,9 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
363363
FmgrInfo*consistentFn;
364364
MemoryContextoldcxt;
365365
MemoryContextperRangeCxt;
366+
BrinMemTuple*dtup;
367+
BrinTuple*btup=NULL;
368+
Sizebtupsz=0;
366369

367370
opaque= (BrinOpaque*)scan->opaque;
368371
bdesc=opaque->bo_bdesc;
@@ -384,6 +387,9 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
384387
*/
385388
consistentFn=palloc0(sizeof(FmgrInfo)*bdesc->bd_tupdesc->natts);
386389

390+
/* allocate an initial in-memory tuple, out of the per-range memcxt */
391+
dtup=brin_new_memtuple(bdesc);
392+
387393
/*
388394
* Setup and use a per-range memory context, which is reset every time we
389395
* loop below. This avoids having to free the tuples within the loop.
@@ -401,6 +407,7 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
401407
for (heapBlk=0;heapBlk<nblocks;heapBlk+=opaque->bo_pagesPerRange)
402408
{
403409
booladdrange;
410+
boolgottuple= false;
404411
BrinTuple*tup;
405412
OffsetNumberoff;
406413
Sizesize;
@@ -414,23 +421,22 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
414421
scan->xs_snapshot);
415422
if (tup)
416423
{
417-
tup=brin_copy_tuple(tup,size);
424+
gottuple= true;
425+
btup=brin_copy_tuple(tup,size,btup,&btupsz);
418426
LockBuffer(buf,BUFFER_LOCK_UNLOCK);
419427
}
420428

421429
/*
422430
* For page ranges with no indexed tuple, we must return the whole
423431
* range; otherwise, compare it to the scan keys.
424432
*/
425-
if (tup==NULL)
433+
if (!gottuple)
426434
{
427435
addrange= true;
428436
}
429437
else
430438
{
431-
BrinMemTuple*dtup;
432-
433-
dtup=brin_deform_tuple(bdesc,tup);
439+
dtup=brin_deform_tuple(bdesc,btup,dtup);
434440
if (dtup->bt_placeholder)
435441
{
436442
/*
@@ -1210,7 +1216,7 @@ summarize_range(IndexInfo *indexInfo, BrinBuildState *state, Relation heapRel,
12101216
/* the placeholder tuple must exist */
12111217
if (phtup==NULL)
12121218
elog(ERROR,"missing placeholder tuple");
1213-
phtup=brin_copy_tuple(phtup,phsz);
1219+
phtup=brin_copy_tuple(phtup,phsz,NULL,NULL);
12141220
LockBuffer(phbuf,BUFFER_LOCK_UNLOCK);
12151221

12161222
/* merge it into the tuple from the heap scan */
@@ -1358,7 +1364,7 @@ union_tuples(BrinDesc *bdesc, BrinMemTuple *a, BrinTuple *b)
13581364
"brin union",
13591365
ALLOCSET_DEFAULT_SIZES);
13601366
oldcxt=MemoryContextSwitchTo(cxt);
1361-
db=brin_deform_tuple(bdesc,b);
1367+
db=brin_deform_tuple(bdesc,b,NULL);
13621368
MemoryContextSwitchTo(oldcxt);
13631369

13641370
for (keyno=0;keyno<bdesc->bd_tupdesc->natts;keyno++)

‎src/backend/access/brin/brin_pageops.c

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -548,6 +548,8 @@ brin_evacuate_page(Relation idxRel, BlockNumber pagesPerRange,
548548
OffsetNumberoff;
549549
OffsetNumbermaxoff;
550550
Pagepage;
551+
BrinTuple*btup=NULL;
552+
Sizebtupsz=0;
551553

552554
page=BufferGetPage(buf);
553555

@@ -567,7 +569,7 @@ brin_evacuate_page(Relation idxRel, BlockNumber pagesPerRange,
567569
{
568570
sz=ItemIdGetLength(lp);
569571
tup= (BrinTuple*)PageGetItem(page,lp);
570-
tup=brin_copy_tuple(tup,sz);
572+
tup=brin_copy_tuple(tup,sz,btup,&btupsz);
571573

572574
LockBuffer(buf,BUFFER_LOCK_UNLOCK);
573575

‎src/backend/access/brin/brin_tuple.c

Lines changed: 49 additions & 28 deletions
Original file line numberDiff line numberDiff line change
@@ -311,17 +311,26 @@ brin_free_tuple(BrinTuple *tuple)
311311
}
312312

313313
/*
314-
* Create a palloc'd copy of a BrinTuple.
314+
* Given a brin tuple of size len, create a copy of it. If 'dest' is not
315+
* NULL, its size is destsz, and can be used as output buffer; if the tuple
316+
* to be copied does not fit, it is enlarged by repalloc, and the size is
317+
* updated to match. This avoids palloc/free cycles when many brin tuples
318+
* are being processed in loops.
315319
*/
316320
BrinTuple*
317-
brin_copy_tuple(BrinTuple*tuple,Sizelen)
321+
brin_copy_tuple(BrinTuple*tuple,Sizelen,BrinTuple*dest,Size*destsz)
318322
{
319-
BrinTuple*newtup;
323+
if (!destsz||*destsz==0)
324+
dest=palloc(len);
325+
elseif (len>*destsz)
326+
{
327+
dest=repalloc(dest,len);
328+
*destsz=len;
329+
}
320330

321-
newtup=palloc(len);
322-
memcpy(newtup,tuple,len);
331+
memcpy(dest,tuple,len);
323332

324-
returnnewtup;
333+
returndest;
325334
}
326335

327336
/*
@@ -348,54 +357,69 @@ BrinMemTuple *
348357
brin_new_memtuple(BrinDesc*brdesc)
349358
{
350359
BrinMemTuple*dtup;
351-
char*currdatum;
352360
longbasesize;
353-
inti;
354361

355362
basesize=MAXALIGN(sizeof(BrinMemTuple)+
356363
sizeof(BrinValues)*brdesc->bd_tupdesc->natts);
357364
dtup=palloc0(basesize+sizeof(Datum)*brdesc->bd_totalstored);
358-
currdatum= (char*)dtup+basesize;
359-
for (i=0;i<brdesc->bd_tupdesc->natts;i++)
360-
{
361-
dtup->bt_columns[i].bv_attno=i+1;
362-
dtup->bt_columns[i].bv_allnulls= true;
363-
dtup->bt_columns[i].bv_hasnulls= false;
364-
dtup->bt_columns[i].bv_values= (Datum*)currdatum;
365-
currdatum+=sizeof(Datum)*brdesc->bd_info[i]->oi_nstored;
366-
}
365+
366+
dtup->bt_values=palloc(sizeof(Datum)*brdesc->bd_totalstored);
367+
dtup->bt_allnulls=palloc(sizeof(bool)*brdesc->bd_tupdesc->natts);
368+
dtup->bt_hasnulls=palloc(sizeof(bool)*brdesc->bd_tupdesc->natts);
367369

368370
dtup->bt_context=AllocSetContextCreate(CurrentMemoryContext,
369371
"brin dtuple",
370372
ALLOCSET_DEFAULT_SIZES);
373+
374+
brin_memtuple_initialize(dtup,brdesc);
375+
371376
returndtup;
372377
}
373378

374379
/*
375-
* Reset a BrinMemTuple to initial state
380+
* Reset a BrinMemTuple to initial state. We return the same tuple, for
381+
* notational convenience.
376382
*/
377-
void
383+
BrinMemTuple*
378384
brin_memtuple_initialize(BrinMemTuple*dtuple,BrinDesc*brdesc)
379385
{
380386
inti;
387+
char*currdatum;
381388

382389
MemoryContextReset(dtuple->bt_context);
390+
391+
currdatum= (char*)dtuple+
392+
MAXALIGN(sizeof(BrinMemTuple)+
393+
sizeof(BrinValues)*brdesc->bd_tupdesc->natts);
383394
for (i=0;i<brdesc->bd_tupdesc->natts;i++)
384395
{
385396
dtuple->bt_columns[i].bv_allnulls= true;
386397
dtuple->bt_columns[i].bv_hasnulls= false;
398+
399+
dtuple->bt_columns[i].bv_attno=i+1;
400+
dtuple->bt_columns[i].bv_allnulls= true;
401+
dtuple->bt_columns[i].bv_hasnulls= false;
402+
dtuple->bt_columns[i].bv_values= (Datum*)currdatum;
403+
currdatum+=sizeof(Datum)*brdesc->bd_info[i]->oi_nstored;
387404
}
405+
406+
returndtuple;
388407
}
389408

390409
/*
391410
* Convert a BrinTuple back to a BrinMemTuple. This is the reverse of
392411
* brin_form_tuple.
393412
*
413+
* As an optimization, the caller can pass a previously allocated 'dMemtuple'.
414+
* This avoids having to allocate it here, which can be useful when this
415+
* function is called many times in a loop. It is caller's responsibility
416+
* that the given BrinMemTuple matches what we need here.
417+
*
394418
* Note we don't need the "on disk tupdesc" here; we rely on our own routine to
395419
* deconstruct the tuple from the on-disk format.
396420
*/
397421
BrinMemTuple*
398-
brin_deform_tuple(BrinDesc*brdesc,BrinTuple*tuple)
422+
brin_deform_tuple(BrinDesc*brdesc,BrinTuple*tuple,BrinMemTuple*dMemtuple)
399423
{
400424
BrinMemTuple*dtup;
401425
Datum*values;
@@ -407,15 +431,16 @@ brin_deform_tuple(BrinDesc *brdesc, BrinTuple *tuple)
407431
intvalueno;
408432
MemoryContextoldcxt;
409433

410-
dtup=brin_new_memtuple(brdesc);
434+
dtup=dMemtuple ?brin_memtuple_initialize(dMemtuple,brdesc) :
435+
brin_new_memtuple(brdesc);
411436

412437
if (BrinTupleIsPlaceholder(tuple))
413438
dtup->bt_placeholder= true;
414439
dtup->bt_blkno=tuple->bt_blkno;
415440

416-
values=palloc(sizeof(Datum)*brdesc->bd_totalstored);
417-
allnulls=palloc(sizeof(bool)*brdesc->bd_tupdesc->natts);
418-
hasnulls=palloc(sizeof(bool)*brdesc->bd_tupdesc->natts);
441+
values=dtup->bt_values;
442+
allnulls=dtup->bt_allnulls;
443+
hasnulls=dtup->bt_hasnulls;
419444

420445
tp= (char*)tuple+BrinTupleDataOffset(tuple);
421446

@@ -458,10 +483,6 @@ brin_deform_tuple(BrinDesc *brdesc, BrinTuple *tuple)
458483

459484
MemoryContextSwitchTo(oldcxt);
460485

461-
pfree(values);
462-
pfree(allnulls);
463-
pfree(hasnulls);
464-
465486
returndtup;
466487
}
467488

‎src/include/access/brin_tuple.h

Lines changed: 9 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -38,6 +38,11 @@ typedef struct BrinMemTuple
3838
boolbt_placeholder;/* this is a placeholder tuple */
3939
BlockNumberbt_blkno;/* heap blkno that the tuple is for */
4040
MemoryContextbt_context;/* memcxt holding the bt_columns values */
41+
/* output arrays for brin_deform_tuple: */
42+
Datum*bt_values;/* values array */
43+
bool*bt_allnulls;/* allnulls array */
44+
bool*bt_hasnulls;/* hasnulls array */
45+
/* not an output array, but must be last */
4146
BrinValuesbt_columns[FLEXIBLE_ARRAY_MEMBER];
4247
}BrinMemTuple;
4348

@@ -83,14 +88,15 @@ extern BrinTuple *brin_form_tuple(BrinDesc *brdesc, BlockNumber blkno,
8388
externBrinTuple*brin_form_placeholder_tuple(BrinDesc*brdesc,
8489
BlockNumberblkno,Size*size);
8590
externvoidbrin_free_tuple(BrinTuple*tuple);
86-
externBrinTuple*brin_copy_tuple(BrinTuple*tuple,Sizelen);
91+
externBrinTuple*brin_copy_tuple(BrinTuple*tuple,Sizelen,
92+
BrinTuple*dest,Size*destsz);
8793
externboolbrin_tuples_equal(constBrinTuple*a,Sizealen,
8894
constBrinTuple*b,Sizeblen);
8995

9096
externBrinMemTuple*brin_new_memtuple(BrinDesc*brdesc);
91-
externvoidbrin_memtuple_initialize(BrinMemTuple*dtuple,
97+
externBrinMemTuple*brin_memtuple_initialize(BrinMemTuple*dtuple,
9298
BrinDesc*brdesc);
9399
externBrinMemTuple*brin_deform_tuple(BrinDesc*brdesc,
94-
BrinTuple*tuple);
100+
BrinTuple*tuple,BrinMemTuple*dMemtuple);
95101

96102
#endif/* BRIN_TUPLE_H */

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