From: | elein <elein(at)varlena(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: InitPostgres and flatfiles question |
Date: | 2007-01-07 01:40:07 |
Message-ID: | 20070107014007.GN24367@varlena.com |
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Lists: | pgsql-hackers |
On Fri, Jan 05, 2007 at 08:45:51PM -0500, Tom Lane wrote:
> Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com> writes:
> > Tom Lane wrote:
> >> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> >>> What value is allowing multiple queies via PQexec()
> >>
> >> The only argument I can think of is that it allows applications to be
> >> sloppy about parsing a SQL script into individual commands before they
> >> send it. (I think initdb may be guilty of exactly that BTW...) At the
> >> same time you could argue that such sloppiness is inherently a Bad Idea.
>
> > Doesn't it also avoid some network(?) overhead when you have
> > a large number of small inserts or updates?
>
> > I seem to recall a previous company where we had a major performance
> > by concatenating a bunch of updates with ";"s in between and sending
> > them to postgresql as a single command.
>
> These days you'd probably be better off using a multi-row VALUES() list
> if relevant. Also, if you really want to send multiple statements like
> that, there's a cleaner way to do it: use the extended query protocol
> and don't Sync or wait for a reply until you've sent them all.
>
> regards, tom lane
>
In shell scripts that do things in the database I often put >1 statement
in the line. Since it is the shell, I want quick results. Usually it
is an INSERT/UPDATE followed by a SELECT.
It would be very frustrating not to be able to send multiple commands
with one -c in psql.
--elein
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