| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Pavan Deolasee <pavan(dot)deolasee(at)enterprisedb(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Subject: | Re: CREATE INDEX and HOT - revised design |
| Date: | 2007-03-21 18:24:26 |
| Message-ID: | 200703211824.l2LIOQd02105@momjian.us |
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| Lists: | pgsql-hackers |
Bruce Momjian wrote:
> > Also, I am wondering whether the information that which index is used to
> > fetch a tuple is always available. I haven't checked, but do we have that
> > information in lossy bitmap heapscan ?
>
> Oh, that is an interesting problem because an index might have one index
> entry representing an entire HOT chain, while another index might
> represent each chain member by individual index entries. When we do the
> bitmaps, don't we access them by heap tid, meaning we would find all
> entries anyway?
I thinking some more, it would be a problem because while we are merging
the tids, we are using index entries and haven't looked at the heap yet.
I am guessing we would have to exclude the new index from bitmap joins
with other indexes until the VACUUM happens.
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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