| From: | ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> |
|---|---|
| To: | Greg Stark <gsstark(at)mit(dot)edu> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Another idea for dealing with cmin/cmax |
| Date: | 2006-10-03 04:02:58 |
| Message-ID: | 20061003124620.5F94.ITAGAKI.TAKAHIRO@oss.ntt.co.jp |
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| Lists: | pgsql-hackers |
Greg Stark <gsstark(at)mit(dot)edu> wrote:
> The plan Gavin Sherry and I were discussing at the Code Sprint was to store a
> single "most common xmin" xmin in the per-page special area. Then have a bit
> on each tuple indicating that the xmin isn't present in the tuple and instead
> to use the xmin from the page footer. Any tuples with other values of xmin
> would have to store that xmin normally.
Is this a similar approach to Interested Transaction List (ITL) in Oracle?
http://www.dbazine.com/oracle/or-articles/nanda3
ITL-like approach is more efficient than per-tuple XIDs
unless all tuples in a page are locked at the same time.
However, MAXTRANS and PCTFREE issues may bother us.
Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center
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