Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit49b6be2

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

File tree

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

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp