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Re: [HACKERS] Trivial patch to double vacuum speed

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Gregory Stark <stark(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org, pgsql-patches(at)postgresql(dot)org
Subject: Re: [HACKERS] Trivial patch to double vacuum speed
Date: 2006-09-04 21:47:02
Message-ID: 200609042147.k84Ll3P04850@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > Patch applied.  Thanks.
> 
> Wait a minute.   This patch changes the behavior so that
> LockBufferForCleanup is applied to *every* heap page, not only the ones
> where there are removable tuples.  It's not hard to imagine scenarios
> where that results in severe system-wide performance degradation.
> Has there been any real-world testing of this idea?

I see the no-index case now:

+               if (nindexes)
+                       LockBuffer(buf, BUFFER_LOCK_SHARE);
+               else
+                       LockBufferForCleanup(buf);

Let's see what Greg says, or revert.

-- 
  Bruce Momjian   bruce(at)momjian(dot)us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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