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Insert into getCopyDataMessage() the same logic that already existed in the

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main code path for enlarging libpq's input buffer in one swoop when needing to
read a long data message.  Without this, the code will double the buffer size,
read more data, notice it still hasn't got the whole message, and repeat till
it finally has a large enough buffer.  Which wastes a lot of data-moving
effort and also memory (since malloc probably can't do anything very useful
with the freed-up smaller buffers).  Not sure why this wasn't there already;
certainly the COPY data path is a place where we're quite likely to see long
data messages.  I'm not backpatching though, since this is just a marginal
performance issue rather than a real bug.
This commit is contained in:
Tom Lane
2008-01-17 21:21:50 +00:00
parent a44174cf90
commit 70066eb1a1
1 changed files with 18 additions and 1 deletions
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19
src/interfaces/libpq/fe-protocol3.c
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@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-protocol3.c,v 1.33 2008/01/15 22:18:20 tgl Exp $ * $PostgreSQL: pgsql/src/interfaces/libpq/fe-protocol3.c,v 1.34 2008/01/17 21:21:50 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -1305,7 +1305,24 @@ getCopyDataMessage(PGconn *conn)
} }
avail = conn->inEnd - conn->inCursor; avail = conn->inEnd - conn->inCursor;
if (avail < msgLength - 4) if (avail < msgLength - 4)
{
/*
* Before returning, enlarge the input buffer if needed to hold
* the whole message. See notes in parseInput.
*/
if (pqCheckInBufferSpace(conn->inCursor + msgLength - 4, conn))
{
/*
* XXX add some better recovery code... plan is to skip over
* the message using its length, then report an error. For the
* moment, just treat this like loss of sync (which indeed it
* might be!)
*/
handleSyncLoss(conn, id, msgLength);
return -2;
}
return 0; return 0;
}
/* /*
* If it's a legitimate async message type, process it. (NOTIFY * If it's a legitimate async message type, process it. (NOTIFY