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Commitf2dec34

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Use one stringbuffer for all rows printed in printtup.c.
This avoids newly allocating, and then possibly growing, thestringbuffer for every row. For wide rows this can substantiallyreduce memory allocator overhead, at the price of not immediatelyreducing memory usage after outputting an especially wide row.Author: Andres FreundDiscussion:https://postgr.es/m/20170914063418.sckdzgjfrsbekae4@alap3.anarazel.de
1 parent1de09ad commitf2dec34

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1 file changed

+25
-21
lines changed

1 file changed

+25
-21
lines changed

‎src/backend/access/common/printtup.c‎

Lines changed: 25 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -57,6 +57,7 @@ typedef struct
5757
typedefstruct
5858
{
5959
DestReceiverpub;/* publicly-known function pointers */
60+
StringInfoDatabuf;/* output buffer */
6061
Portalportal;/* the Portal we are printing from */
6162
boolsendDescrip;/* send RowDescription at startup? */
6263
TupleDescattrinfo;/* The attr info we are set up for */
@@ -127,6 +128,9 @@ printtup_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
127128
DR_printtup*myState= (DR_printtup*)self;
128129
Portalportal=myState->portal;
129130

131+
/* create buffer to be used for all messages */
132+
initStringInfo(&myState->buf);
133+
130134
/*
131135
* Create a temporary memory context that we can reset once per row to
132136
* recover palloc'd memory. This avoids any problems with leaks inside
@@ -302,7 +306,7 @@ printtup(TupleTableSlot *slot, DestReceiver *self)
302306
TupleDesctypeinfo=slot->tts_tupleDescriptor;
303307
DR_printtup*myState= (DR_printtup*)self;
304308
MemoryContextoldcontext;
305-
StringInfoDatabuf;
309+
StringInfobuf=&myState->buf;
306310
intnatts=typeinfo->natts;
307311
inti;
308312

@@ -319,9 +323,9 @@ printtup(TupleTableSlot *slot, DestReceiver *self)
319323
/*
320324
* Prepare a DataRow message (note buffer is in per-row context)
321325
*/
322-
pq_beginmessage(&buf,'D');
326+
pq_beginmessage_reuse(buf,'D');
323327

324-
pq_sendint(&buf,natts,2);
328+
pq_sendint(buf,natts,2);
325329

326330
/*
327331
* send the attributes of this tuple
@@ -333,7 +337,7 @@ printtup(TupleTableSlot *slot, DestReceiver *self)
333337

334338
if (slot->tts_isnull[i])
335339
{
336-
pq_sendint(&buf,-1,4);
340+
pq_sendint(buf,-1,4);
337341
continue;
338342
}
339343

@@ -354,21 +358,21 @@ printtup(TupleTableSlot *slot, DestReceiver *self)
354358
char*outputstr;
355359

356360
outputstr=OutputFunctionCall(&thisState->finfo,attr);
357-
pq_sendcountedtext(&buf,outputstr,strlen(outputstr), false);
361+
pq_sendcountedtext(buf,outputstr,strlen(outputstr), false);
358362
}
359363
else
360364
{
361365
/* Binary output */
362366
bytea*outputbytes;
363367

364368
outputbytes=SendFunctionCall(&thisState->finfo,attr);
365-
pq_sendint(&buf,VARSIZE(outputbytes)-VARHDRSZ,4);
366-
pq_sendbytes(&buf,VARDATA(outputbytes),
369+
pq_sendint(buf,VARSIZE(outputbytes)-VARHDRSZ,4);
370+
pq_sendbytes(buf,VARDATA(outputbytes),
367371
VARSIZE(outputbytes)-VARHDRSZ);
368372
}
369373
}
370374

371-
pq_endmessage(&buf);
375+
pq_endmessage_reuse(buf);
372376

373377
/* Return to caller's context, and flush row's temporary memory */
374378
MemoryContextSwitchTo(oldcontext);
@@ -387,7 +391,7 @@ printtup_20(TupleTableSlot *slot, DestReceiver *self)
387391
TupleDesctypeinfo=slot->tts_tupleDescriptor;
388392
DR_printtup*myState= (DR_printtup*)self;
389393
MemoryContextoldcontext;
390-
StringInfoDatabuf;
394+
StringInfobuf=&myState->buf;
391395
intnatts=typeinfo->natts;
392396
inti,
393397
j,
@@ -406,7 +410,7 @@ printtup_20(TupleTableSlot *slot, DestReceiver *self)
406410
/*
407411
* tell the frontend to expect new tuple data (in ASCII style)
408412
*/
409-
pq_beginmessage(&buf,'D');
413+
pq_beginmessage_reuse(buf,'D');
410414

411415
/*
412416
* send a bitmap of which attributes are not null
@@ -420,13 +424,13 @@ printtup_20(TupleTableSlot *slot, DestReceiver *self)
420424
k >>=1;
421425
if (k==0)/* end of byte? */
422426
{
423-
pq_sendint(&buf,j,1);
427+
pq_sendint(buf,j,1);
424428
j=0;
425429
k=1 <<7;
426430
}
427431
}
428432
if (k!= (1 <<7))/* flush last partial byte */
429-
pq_sendint(&buf,j,1);
433+
pq_sendint(buf,j,1);
430434

431435
/*
432436
* send the attributes of this tuple
@@ -443,10 +447,10 @@ printtup_20(TupleTableSlot *slot, DestReceiver *self)
443447
Assert(thisState->format==0);
444448

445449
outputstr=OutputFunctionCall(&thisState->finfo,attr);
446-
pq_sendcountedtext(&buf,outputstr,strlen(outputstr), true);
450+
pq_sendcountedtext(buf,outputstr,strlen(outputstr), true);
447451
}
448452

449-
pq_endmessage(&buf);
453+
pq_endmessage_reuse(buf);
450454

451455
/* Return to caller's context, and flush row's temporary memory */
452456
MemoryContextSwitchTo(oldcontext);
@@ -572,7 +576,7 @@ printtup_internal_20(TupleTableSlot *slot, DestReceiver *self)
572576
TupleDesctypeinfo=slot->tts_tupleDescriptor;
573577
DR_printtup*myState= (DR_printtup*)self;
574578
MemoryContextoldcontext;
575-
StringInfoDatabuf;
579+
StringInfobuf=&myState->buf;
576580
intnatts=typeinfo->natts;
577581
inti,
578582
j,
@@ -591,7 +595,7 @@ printtup_internal_20(TupleTableSlot *slot, DestReceiver *self)
591595
/*
592596
* tell the frontend to expect new tuple data (in binary style)
593597
*/
594-
pq_beginmessage(&buf,'B');
598+
pq_beginmessage_reuse(buf,'B');
595599

596600
/*
597601
* send a bitmap of which attributes are not null
@@ -605,13 +609,13 @@ printtup_internal_20(TupleTableSlot *slot, DestReceiver *self)
605609
k >>=1;
606610
if (k==0)/* end of byte? */
607611
{
608-
pq_sendint(&buf,j,1);
612+
pq_sendint(buf,j,1);
609613
j=0;
610614
k=1 <<7;
611615
}
612616
}
613617
if (k!= (1 <<7))/* flush last partial byte */
614-
pq_sendint(&buf,j,1);
618+
pq_sendint(buf,j,1);
615619

616620
/*
617621
* send the attributes of this tuple
@@ -628,12 +632,12 @@ printtup_internal_20(TupleTableSlot *slot, DestReceiver *self)
628632
Assert(thisState->format==1);
629633

630634
outputbytes=SendFunctionCall(&thisState->finfo,attr);
631-
pq_sendint(&buf,VARSIZE(outputbytes)-VARHDRSZ,4);
632-
pq_sendbytes(&buf,VARDATA(outputbytes),
635+
pq_sendint(buf,VARSIZE(outputbytes)-VARHDRSZ,4);
636+
pq_sendbytes(buf,VARDATA(outputbytes),
633637
VARSIZE(outputbytes)-VARHDRSZ);
634638
}
635639

636-
pq_endmessage(&buf);
640+
pq_endmessage_reuse(buf);
637641

638642
/* Return to caller's context, and flush row's temporary memory */
639643
MemoryContextSwitchTo(oldcontext);

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