From: | ITAGAKI Takahiro <itagaki(dot)takahiro(at)lab(dot)ntt(dot)co(dot)jp> |
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To: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Why do index access methods use LP_DELETE? |
Date: | 2005-08-12 06:20:13 |
Message-ID: | 20050812144228.4700.ITAGAKI.TAKAHIRO@lab.ntt.co.jp |
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Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > Why do index access methods use LP_DELETE?
>
> My recollection is that I deliberately used LP_DELETE for the
> known-dead-tuple marker so that there couldn't be any confusion with
> the use of LP_USED. AFAIR, LP_USED isn't actually used in indexes,
> so we could do it differently if there were another possible use for
> the flag bit ... have you got one in mind?
Thanks. I understood there is little difference
between non-LP_USED and LP_DELETE for indexes.
I'm thinking to use LP_DELETE for relation tuples for incremental vacuum,
which is discussed in
http://archives.postgresql.org/pgsql-hackers/2005-03/msg00518.php
I'll try to mark tuples with LP_DELETE on visibility checking and
recycle the pages by bgwriter.
...However it is still a stage of an idea.
---
ITAGAKI Takahiro
NTT Cyber Space Laboratories
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