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peterepetere
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Refactor sending of RowDescription messages in replication protocol
Some routines open-coded the construction of RowDescription messages. Instead, we have support for doing this using tuple descriptors and DestRemoteSimple, so use that instead. Reviewed-by: Nathan Bossart <nathandbossart@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/7e4fdbdc-699c-4cd0-115d-fb78a957fc22@enterprisedb.com
1 parent f10a025 commit 2ce648f

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3 files changed

+40
-72
lines changed

3 files changed

+40
-72
lines changed

‎src/backend/access/common/tupdesc.c

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -739,6 +739,15 @@ TupleDescInitBuiltinEntry(TupleDesc desc,
739739
att->attcollation = InvalidOid;
740740
break;
741741

742+
case OIDOID:
743+
att->attlen = 4;
744+
att->attbyval = true;
745+
att->attalign = TYPALIGN_INT;
746+
att->attstorage = TYPSTORAGE_PLAIN;
747+
att->attcompression = InvalidCompressionMethod;
748+
att->attcollation = InvalidOid;
749+
break;
750+
742751
default:
743752
elog(ERROR, "unsupported type %u", oidtypeid);
744753
}

‎src/backend/replication/basebackup_copy.c

Lines changed: 23 additions & 51 deletions
Original file line numberDiff line numberDiff line change
@@ -25,11 +25,13 @@
2525
*/
2626
#include "postgres.h"
2727

28+
#include "access/tupdesc.h"
2829
#include "catalog/pg_type_d.h"
2930
#include "libpq/libpq.h"
3031
#include "libpq/pqformat.h"
3132
#include "replication/basebackup.h"
3233
#include "replication/basebackup_sink.h"
34+
#include "tcop/dest.h"
3335
#include "utils/timestamp.h"
3436

3537
typedef struct bbsink_copystream
@@ -336,35 +338,24 @@ SendCopyDone(void)
336338
static void
337339
SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli)
338340
{
341+
DestReceiver *dest;
342+
TupleDesc tupdesc;
339343
StringInfoData buf;
340344
char str[MAXFNAMELEN];
341345
Size len;
342346

343-
pq_beginmessage(&buf, 'T'); /* RowDescription */
344-
pq_sendint16(&buf, 2); /* 2 fields */
345-
346-
/* Field headers */
347-
pq_sendstring(&buf, "recptr");
348-
pq_sendint32(&buf, 0); /* table oid */
349-
pq_sendint16(&buf, 0); /* attnum */
350-
pq_sendint32(&buf, TEXTOID); /* type oid */
351-
pq_sendint16(&buf, -1);
352-
pq_sendint32(&buf, 0);
353-
pq_sendint16(&buf, 0);
354-
355-
pq_sendstring(&buf, "tli");
356-
pq_sendint32(&buf, 0); /* table oid */
357-
pq_sendint16(&buf, 0); /* attnum */
347+
dest = CreateDestReceiver(DestRemoteSimple);
358348

349+
tupdesc = CreateTemplateTupleDesc(2);
350+
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "recptr", TEXTOID, -1, 0);
359351
/*
360352
* int8 may seem like a surprising data type for this, but in theory int4
361353
* would not be wide enough for this, as TimeLineID is unsigned.
362354
*/
363-
pq_sendint32(&buf, INT8OID); /* type oid */
364-
pq_sendint16(&buf, 8);
365-
pq_sendint32(&buf, 0);
366-
pq_sendint16(&buf, 0);
367-
pq_endmessage(&buf);
355+
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "tli", INT8OID, -1, 0);
356+
357+
/* send RowDescription */
358+
dest->rStartup(dest, CMD_SELECT, tupdesc);
368359

369360
/* Data row */
370361
pq_beginmessage(&buf, 'D');
@@ -391,41 +382,22 @@ SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli)
391382
static void
392383
SendTablespaceList(List *tablespaces)
393384
{
385+
DestReceiver *dest;
386+
TupleDesc tupdesc;
394387
StringInfoData buf;
395388
ListCell *lc;
396389

397-
/* Construct and send the directory information */
398-
pq_beginmessage(&buf, 'T'); /* RowDescription */
399-
pq_sendint16(&buf, 3); /* 3 fields */
400-
401-
/* First field - spcoid */
402-
pq_sendstring(&buf, "spcoid");
403-
pq_sendint32(&buf, 0); /* table oid */
404-
pq_sendint16(&buf, 0); /* attnum */
405-
pq_sendint32(&buf, OIDOID); /* type oid */
406-
pq_sendint16(&buf, 4); /* typlen */
407-
pq_sendint32(&buf, 0); /* typmod */
408-
pq_sendint16(&buf, 0); /* format code */
409-
410-
/* Second field - spclocation */
411-
pq_sendstring(&buf, "spclocation");
412-
pq_sendint32(&buf, 0);
413-
pq_sendint16(&buf, 0);
414-
pq_sendint32(&buf, TEXTOID);
415-
pq_sendint16(&buf, -1);
416-
pq_sendint32(&buf, 0);
417-
pq_sendint16(&buf, 0);
418-
419-
/* Third field - size */
420-
pq_sendstring(&buf, "size");
421-
pq_sendint32(&buf, 0);
422-
pq_sendint16(&buf, 0);
423-
pq_sendint32(&buf, INT8OID);
424-
pq_sendint16(&buf, 8);
425-
pq_sendint32(&buf, 0);
426-
pq_sendint16(&buf, 0);
427-
pq_endmessage(&buf);
390+
dest = CreateDestReceiver(DestRemoteSimple);
391+
392+
tupdesc = CreateTemplateTupleDesc(3);
393+
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "spcoid", OIDOID, -1, 0);
394+
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "spclocation", TEXTOID, -1, 0);
395+
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "size", INT8OID, -1, 0);
428396

397+
/* send RowDescription */
398+
dest->rStartup(dest, CMD_SELECT, tupdesc);
399+
400+
/* Construct and send the directory information */
429401
foreach(lc, tablespaces)
430402
{
431403
tablespaceinfo *ti = lfirst(lc);

‎src/backend/replication/walsender.c

Lines changed: 8 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -579,6 +579,8 @@ ReadReplicationSlot(ReadReplicationSlotCmd *cmd)
579579
static void
580580
SendTimeLineHistory(TimeLineHistoryCmd *cmd)
581581
{
582+
DestReceiver *dest;
583+
TupleDesc tupdesc;
582584
StringInfoData buf;
583585
char histfname[MAXFNAMELEN];
584586
char path[MAXPGPATH];
@@ -587,36 +589,21 @@ SendTimeLineHistory(TimeLineHistoryCmd *cmd)
587589
off_t bytesleft;
588590
Size len;
589591

592+
dest = CreateDestReceiver(DestRemoteSimple);
593+
590594
/*
591595
* Reply with a result set with one row, and two columns. The first col is
592596
* the name of the history file, 2nd is the contents.
593597
*/
598+
tupdesc = CreateTemplateTupleDesc(2);
599+
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "filename", TEXTOID, -1, 0);
600+
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "content", TEXTOID, -1, 0);
594601

595602
TLHistoryFileName(histfname, cmd->timeline);
596603
TLHistoryFilePath(path, cmd->timeline);
597604

598605
/* Send a RowDescription message */
599-
pq_beginmessage(&buf, 'T');
600-
pq_sendint16(&buf, 2); /* 2 fields */
601-
602-
/* first field */
603-
pq_sendstring(&buf, "filename"); /* col name */
604-
pq_sendint32(&buf, 0); /* table oid */
605-
pq_sendint16(&buf, 0); /* attnum */
606-
pq_sendint32(&buf, TEXTOID); /* type oid */
607-
pq_sendint16(&buf, -1); /* typlen */
608-
pq_sendint32(&buf, 0); /* typmod */
609-
pq_sendint16(&buf, 0); /* format code */
610-
611-
/* second field */
612-
pq_sendstring(&buf, "content"); /* col name */
613-
pq_sendint32(&buf, 0); /* table oid */
614-
pq_sendint16(&buf, 0); /* attnum */
615-
pq_sendint32(&buf, TEXTOID); /* type oid */
616-
pq_sendint16(&buf, -1); /* typlen */
617-
pq_sendint32(&buf, 0); /* typmod */
618-
pq_sendint16(&buf, 0); /* format code */
619-
pq_endmessage(&buf);
606+
dest->rStartup(dest, CMD_SELECT, tupdesc);
620607

621608
/* Send a DataRow message */
622609
pq_beginmessage(&buf, 'D');

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