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Commitd26bf23

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Arrange to squeeze out the MINIMAL_TUPLE_PADDING in the tuple representation
written to temp files by tuplesort.c and tuplestore.c. This saves 2 bytes perrow for 32-bit machines, and 6 bytes per row for 64-bit machines, which seemsworth the slight additional uglification of the tuple read/write routines.
1 parent8ecd535 commitd26bf23

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3 files changed

+42
-22
lines changed

3 files changed

+42
-22
lines changed

‎src/backend/utils/sort/tuplesort.c

Lines changed: 16 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -91,7 +91,7 @@
9191
* Portions Copyright (c) 1994, Regents of the University of California
9292
*
9393
* IDENTIFICATION
94-
* $PostgreSQL: pgsql/src/backend/utils/sort/tuplesort.c,v 1.87 2008/09/15 18:43:41 tgl Exp $
94+
* $PostgreSQL: pgsql/src/backend/utils/sort/tuplesort.c,v 1.88 2008/10/28 15:51:03 tgl Exp $
9595
*
9696
*-------------------------------------------------------------------------
9797
*/
@@ -2632,18 +2632,20 @@ copytup_heap(Tuplesortstate *state, SortTuple *stup, void *tup)
26322632
&stup->isnull1);
26332633
}
26342634

2635-
/*
2636-
* Since MinimalTuple already has length in its first word, we don't need
2637-
* to write that separately.
2638-
*/
26392635
staticvoid
26402636
writetup_heap(Tuplesortstate*state,inttapenum,SortTuple*stup)
26412637
{
26422638
MinimalTupletuple= (MinimalTuple)stup->tuple;
2643-
unsignedinttuplen=tuple->t_len;
2639+
/* the part of the MinimalTuple we'll write: */
2640+
char*tupbody= (char*)tuple+MINIMAL_TUPLE_DATA_OFFSET;
2641+
unsignedinttupbodylen=tuple->t_len-MINIMAL_TUPLE_DATA_OFFSET;
2642+
/* total on-disk footprint: */
2643+
unsignedinttuplen=tupbodylen+sizeof(int);
26442644

26452645
LogicalTapeWrite(state->tapeset,tapenum,
2646-
(void*)tuple,tuplen);
2646+
(void*)&tuplen,sizeof(tuplen));
2647+
LogicalTapeWrite(state->tapeset,tapenum,
2648+
(void*)tupbody,tupbodylen);
26472649
if (state->randomAccess)/* need trailing length word? */
26482650
LogicalTapeWrite(state->tapeset,tapenum,
26492651
(void*)&tuplen,sizeof(tuplen));
@@ -2656,16 +2658,18 @@ static void
26562658
readtup_heap(Tuplesortstate*state,SortTuple*stup,
26572659
inttapenum,unsignedintlen)
26582660
{
2659-
MinimalTupletuple= (MinimalTuple)palloc(len);
2660-
unsignedinttuplen;
2661+
unsignedinttupbodylen=len-sizeof(int);
2662+
unsignedinttuplen=tupbodylen+MINIMAL_TUPLE_DATA_OFFSET;
2663+
MinimalTupletuple= (MinimalTuple)palloc(tuplen);
2664+
char*tupbody= (char*)tuple+MINIMAL_TUPLE_DATA_OFFSET;
26612665
HeapTupleDatahtup;
26622666

26632667
USEMEM(state,GetMemoryChunkSpace(tuple));
26642668
/* read in the tuple proper */
2665-
tuple->t_len=len;
2669+
tuple->t_len=tuplen;
26662670
if (LogicalTapeRead(state->tapeset,tapenum,
2667-
(void*)((char*)tuple+sizeof(int)),
2668-
len-sizeof(int))!= (size_t)(len-sizeof(int)))
2671+
(void*)tupbody,
2672+
tupbodylen)!= (size_t)tupbodylen)
26692673
elog(ERROR,"unexpected end of data");
26702674
if (state->randomAccess)/* need trailing length word? */
26712675
if (LogicalTapeRead(state->tapeset,tapenum, (void*)&tuplen,

‎src/backend/utils/sort/tuplestore.c

Lines changed: 19 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -46,7 +46,7 @@
4646
* Portions Copyright (c) 1994, Regents of the University of California
4747
*
4848
* IDENTIFICATION
49-
* $PostgreSQL: pgsql/src/backend/utils/sort/tuplestore.c,v 1.42 2008/10/07 00:05:55 tgl Exp $
49+
* $PostgreSQL: pgsql/src/backend/utils/sort/tuplestore.c,v 1.43 2008/10/28 15:51:03 tgl Exp $
5050
*
5151
*-------------------------------------------------------------------------
5252
*/
@@ -1173,9 +1173,17 @@ static void
11731173
writetup_heap(Tuplestorestate*state,void*tup)
11741174
{
11751175
MinimalTupletuple= (MinimalTuple)tup;
1176-
unsignedinttuplen=tuple->t_len;
1177-
1178-
if (BufFileWrite(state->myfile, (void*)tuple,tuplen)!= (size_t)tuplen)
1176+
/* the part of the MinimalTuple we'll write: */
1177+
char*tupbody= (char*)tuple+MINIMAL_TUPLE_DATA_OFFSET;
1178+
unsignedinttupbodylen=tuple->t_len-MINIMAL_TUPLE_DATA_OFFSET;
1179+
/* total on-disk footprint: */
1180+
unsignedinttuplen=tupbodylen+sizeof(int);
1181+
1182+
if (BufFileWrite(state->myfile, (void*)&tuplen,
1183+
sizeof(tuplen))!=sizeof(tuplen))
1184+
elog(ERROR,"write failed");
1185+
if (BufFileWrite(state->myfile, (void*)tupbody,
1186+
tupbodylen)!= (size_t)tupbodylen)
11791187
elog(ERROR,"write failed");
11801188
if (state->backward)/* need trailing length word? */
11811189
if (BufFileWrite(state->myfile, (void*)&tuplen,
@@ -1189,14 +1197,16 @@ writetup_heap(Tuplestorestate *state, void *tup)
11891197
staticvoid*
11901198
readtup_heap(Tuplestorestate*state,unsignedintlen)
11911199
{
1192-
MinimalTupletuple= (MinimalTuple)palloc(len);
1193-
unsignedinttuplen;
1200+
unsignedinttupbodylen=len-sizeof(int);
1201+
unsignedinttuplen=tupbodylen+MINIMAL_TUPLE_DATA_OFFSET;
1202+
MinimalTupletuple= (MinimalTuple)palloc(tuplen);
1203+
char*tupbody= (char*)tuple+MINIMAL_TUPLE_DATA_OFFSET;
11941204

11951205
USEMEM(state,GetMemoryChunkSpace(tuple));
11961206
/* read in the tuple proper */
1197-
tuple->t_len=len;
1198-
if (BufFileRead(state->myfile, (void*)((char*)tuple+sizeof(int)),
1199-
len-sizeof(int))!= (size_t)(len-sizeof(int)))
1207+
tuple->t_len=tuplen;
1208+
if (BufFileRead(state->myfile, (void*)tupbody,
1209+
tupbodylen)!= (size_t)tupbodylen)
12001210
elog(ERROR,"unexpected end of data");
12011211
if (state->backward)/* need trailing length word? */
12021212
if (BufFileRead(state->myfile, (void*)&tuplen,

‎src/include/access/htup.h

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/access/htup.h,v 1.101 2008/08/11 11:05:11 heikki Exp $
10+
* $PostgreSQL: pgsql/src/include/access/htup.h,v 1.102 2008/10/28 15:51:03 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -420,11 +420,17 @@ do { \
420420
*
421421
* Note that t_hoff is computed the same as in a full tuple, hence it includes
422422
* the MINIMAL_TUPLE_OFFSET distance. t_len does not include that, however.
423+
*
424+
* MINIMAL_TUPLE_DATA_OFFSET is the offset to the first useful (non-pad) data
425+
* other than the length word. tuplesort.c and tuplestore.c use this to avoid
426+
* writing the padding to disk.
423427
*/
424428
#defineMINIMAL_TUPLE_OFFSET \
425429
((offsetof(HeapTupleHeaderData, t_infomask2) - sizeof(uint32)) / MAXIMUM_ALIGNOF * MAXIMUM_ALIGNOF)
426430
#defineMINIMAL_TUPLE_PADDING \
427431
((offsetof(HeapTupleHeaderData, t_infomask2) - sizeof(uint32)) % MAXIMUM_ALIGNOF)
432+
#defineMINIMAL_TUPLE_DATA_OFFSET \
433+
offsetof(MinimalTupleData, t_infomask2)
428434

429435
typedefstructMinimalTupleData
430436
{

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