From: | bruc(at)stone(dot)congenomics(dot)com (Robert E(dot) Bruccoleri) |
---|---|
To: | tgl(at)sss(dot)pgh(dot)pa(dot)us (Tom Lane) |
Cc: | pgsql-bugs(at)postgresql(dot)org |
Subject: | Re: Apparent deadlock for simultaneous sequential scans |
Date: | 2001-06-08 13:32:38 |
Message-ID: | 200106081332.JAA70934@stone.congenomics.com |
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Lists: | pgsql-bugs |
Dear Tom,
>
>
> pgsql-bugs(at)postgresql(dot)org writes:
> > Apparent deadlock for simultaneous sequential scans
>
> > However, if more than one application is run at once, the performance
> > deteriotates drastically.
>
> So is it a deadlock, or a slowdown? How many is "more than one"?
With two processors running the same query, it appears to be a
slowdown. When I look at the system calls, the backends were
executing about one read per second. With six processors running the
same query, it appeared to be a deadlock -- no I/O's were being issued
over the time that I watched.
"More than one" means two or more.
Thanks. --Bob
+----------------------------------+------------------------------------+
| Robert E. Bruccoleri, Ph.D. | Phone: 609 737 6383 |
| President, Congenomics, Inc. | Fax: 609 737 7528 |
| 114 W Franklin Ave, Suite K1,4,5 | email: bruc(at)acm(dot)org |
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