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Commit49b6be2

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Tighten coding of inner loops in nocachegetattr ...
seems to have improved speed of routine by 5% or so ...
1 parent1857754 commit49b6be2

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1 file changed

+33
-41
lines changed

1 file changed

+33
-41
lines changed

‎src/backend/access/common/heaptuple.c

Lines changed: 33 additions & 41 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/access/common/heaptuple.c,v 1.46 1998/11/27 19:51:27 vadim Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/access/common/heaptuple.c,v 1.47 1999/01/24 22:53:25 tgl Exp $
1212
*
1313
* NOTES
1414
* The old interface functions have been converted to macros
@@ -311,13 +311,13 @@ heap_getsysattr(HeapTuple tup, Buffer b, int attnum)
311311
*
312312
*This caches attribute offsets in the attribute descriptor.
313313
*
314-
*an alternate way to speed things up would be to cache offsets
314+
*An alternate way to speed things up would be to cache offsets
315315
*with the tuple, but that seems more difficult unless you take
316316
*the storage hit of actually putting those offsets into the
317317
*tuple you send to disk. Yuck.
318318
*
319319
*This scheme will be slightly slower than that, but should
320-
*preform well for queries which hit large #'s of tuples. After
320+
*perform well for queries which hit large #'s of tuples. After
321321
*you cache the offsets once, examining all the other tuples using
322322
*the same attribute descriptor will go much quicker. -cim 5/4/91
323323
* ----------------
@@ -331,8 +331,8 @@ nocachegetattr(HeapTuple tuple,
331331
char*tp;/* ptr to att in tuple */
332332
HeapTupleHeadertup=tuple->t_data;
333333
bits8*bp=tup->t_bits;/* ptr to att in tuple */
334-
intslow;/* do we have to walk nulls? */
335334
Form_pg_attribute*att=tupleDesc->attrs;
335+
intslow=0;/* do we have to walk nulls? */
336336

337337

338338
#ifIN_MACRO
@@ -343,6 +343,8 @@ nocachegetattr(HeapTuple tuple,
343343
*isnull= false;
344344
#endif
345345

346+
attnum--;
347+
346348
/* ----------------
347349
* Three cases:
348350
*
@@ -354,8 +356,6 @@ nocachegetattr(HeapTuple tuple,
354356

355357
if (HeapTupleNoNulls(tuple))
356358
{
357-
attnum--;
358-
359359
#ifIN_MACRO
360360
/* This is handled in the macro */
361361
if (att[attnum]->attcacheoff!=-1)
@@ -373,20 +373,13 @@ nocachegetattr(HeapTuple tuple,
373373
return (Datum)fetchatt(&(att[0]), (char*)tup+tup->t_hoff);
374374
}
375375
#endif
376-
377-
slow=0;
378376
}
379377
else
380378
{
381-
382379
/*
383380
* there's a null somewhere in the tuple
384381
*/
385382

386-
tp= (char*)tup+tup->t_hoff;
387-
slow=0;
388-
attnum--;
389-
390383
/* ----------------
391384
*check to see if desired att is null
392385
* ----------------
@@ -403,34 +396,27 @@ nocachegetattr(HeapTuple tuple,
403396
#endif
404397

405398
/* ----------------
406-
*Now check to see if anypreceeding bits are null...
399+
*Now check to see if anypreceding bits are null...
407400
* ----------------
408401
*/
409402
{
410-
inti=0;/* current offset in bp */
411-
intmask;/* bit in byte we're looking at */
412-
charn;/* current byte in bp */
413-
intbyte,
414-
finalbit;
415-
416-
byte=attnum >>3;
417-
finalbit=attnum&0x07;
403+
intbyte=attnum >>3;
404+
intfinalbit=attnum&0x07;
418405

419-
for (;i <=byte&& !slow;i++)
406+
/* check for nulls "before" final bit of last byte */
407+
if ((~bp[byte])& ((1 <<finalbit)-1))
408+
slow=1;
409+
else
420410
{
421-
n=bp[i];
422-
if (i<byte)
411+
/* check for nulls in any "earlier" bytes */
412+
inti;
413+
for (i=0;i<byte;i++)
423414
{
424-
/* check for nulls in any "earlier" bytes */
425-
if ((~n)!=0)
426-
slow=1;
427-
}
428-
else
429-
{
430-
/* check for nulls "before" final bit of last byte */
431-
mask= (1 <<finalbit)-1;
432-
if ((~n)&mask)
415+
if (bp[i]!=0xFF)
416+
{
433417
slow=1;
418+
break;
419+
}
434420
}
435421
}
436422
}
@@ -449,24 +435,29 @@ nocachegetattr(HeapTuple tuple,
449435
tp+att[attnum]->attcacheoff);
450436
}
451437
elseif (attnum==0)
452-
return (Datum)fetchatt(&(att[0]),(char*)tp);
438+
return (Datum)fetchatt(&(att[0]),tp);
453439
elseif (!HeapTupleAllFixed(tuple))
454440
{
455-
intj=0;
456-
441+
intj;
457442
/*
458443
* In for(), we make this <= and not < because we want to test
459444
* if we can go past it in initializing offsets.
460445
*/
461-
for (j=0;j <=attnum&& !slow;j++)
446+
for (j=0;j <=attnum;j++)
447+
{
462448
if (att[j]->attlen<1&& !VARLENA_FIXED_SIZE(att[j]))
449+
{
463450
slow=1;
451+
break;
452+
}
453+
}
464454
}
465455
}
466456

467457
/*
468-
* if slow is zero, and we got here, we know that we have a tuple with
469-
* no nulls. We also have to initialize the remainder of the
458+
* If slow is zero, and we got here, we know that we have a tuple with
459+
* no nulls or varlenas before the target attribute.
460+
* If possible, we also want to initialize the remainder of the
470461
* attribute cached offset values.
471462
*/
472463
if (!slow)
@@ -550,7 +541,8 @@ nocachegetattr(HeapTuple tuple,
550541

551542
off=att_addlength(off,att[i]->attlen,tp+off);
552543

553-
if (att[i]->attlen==-1&& !VARLENA_FIXED_SIZE(att[i]))
544+
if (usecache&&
545+
att[i]->attlen==-1&& !VARLENA_FIXED_SIZE(att[i]))
554546
usecache= false;
555547
}
556548

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