Re: Copy

From: John Coers <coers(at)intrinsity(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Copy
Date: 2001-05-01 15:49:11
Message-ID: 3AEEDAF7.F1FA2AB6@intrinsity.com
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Tom Lane wrote:
>
> John Coers <coers(at)intrinsity(dot)com> writes:
> > Does a COPY FROM block? In case I am using the wrong terminology,
> > what I need to know is if I have multiple clients performing COPY FROM...PQputline()
> > using asynchronous connections, will I lose data?
>
> No.
>
> > Will the server simply execute them serially?
>
> They'll be executed in parallel, just the same as if each client had
> done a bunch of INSERTs wrapped in a BEGIN/END block. You'd only see
> problems if clients inserted conflicting data (eg, identical keys in
> a column with a UNIQUE index). You may care to read the documentation
> about multi-version concurrency control and locking.
>
> regards, tom lane

hmmmm...I get best performance with N=2 and force the clients to keep trying to
get a connection. If I leave the default of N=32 the machine gets bogged down
to a complete standstill by 32 copies of 15k rows of data. The CPU doesn't seem
stressed -- what may be causing the bottleneck?

--
John Coers Intrinsity, Inc.
coers(at)intrinsity(dot)com Austin, Texas

In response to

  • Re: Copy at 2001-04-30 22:16:06 from Tom Lane

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