Re: batching commands with libpq - Mailing list pgsql-novice

From yamt@mwd.biglobe.ne.jp (YAMAMOTO Takashi)
Subject Re: batching commands with libpq
Date
Msg-id 20110113000859.EDC1419CEBA@mail.netbsd.org
Whole thread Raw
In response to Re: batching commands with libpq  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: batching commands with libpq  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-novice
hi,

> yamt@mwd.biglobe.ne.jp (YAMAMOTO Takashi) writes:
>> is there any way to send multiple commands together (ideally in a single
>> network packet), and then wait for their results, using libpq?  i want to
>> save extra round-trips.  while postgresql's fe-be on-wire protocol seems
>> to allow it (is it right?), i couldn't find a way with libpq.
>
>> PQsendQuery(conn, "select timeofday();select timeofday();select timeofday();");
>> seems to work, but i want to use extended protocol.
>
> You're out of luck: extended protocol intentionally doesn't allow
> multiple queries per string.
>
> The wire protocol does in theory allow you to send more commands before
> waiting for the results of the first one, but that's not supported in
> libpq.  The only case you can do in libpq is multiple commands in a
> PQexec string.

thanks for explanation.
do you think it's worth extending the libpq api to allow two or
more in-flight commands?

YAMAMOTO Takashi

>
>             regards, tom lane

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