| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> |
| Cc: | "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com>, "Gregory Stark" <stark(at)enterprisedb(dot)com>, "Bruce Momjian" <bruce(at)momjian(dot)us>, "Florian Pflug" <fgp(dot)phlo(dot)org(at)gmail(dot)com>, "Simon Riggs" <simon(at)2ndquadrant(dot)com>, "PostgreSQL-patches" <pgsql-patches(at)postgresql(dot)org> |
| Subject: | Re: HOT patch - version 15 |
| Date: | 2007-09-11 15:28:40 |
| Message-ID: | 28819.1189524520@sss.pgh.pa.us |
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| Lists: | pgsql-patches |
"Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> writes:
> Tom Lane wrote:
>> Then you don't remember far enough --- either the HeapTupleHeader change
>> or the varvarlena change would be enough to prevent that. For that
>> matter, the pd_flags header field that the patch is already relying on
>> is new for 8.3.
> Yeah, those changes will need to be dealt with in the conversion. But
> none of the changes this far have increased the on-disk size. Adding a
> new field to page header means that in some corner cases it might not be
> possible to convert a page from old format to the new one because the
> data no longer fits.
Counting on my fingers, it seems that the 4-byte savings in
HeapTupleHeader size would guarantee that adding 4 bytes to the page
header wouldn't kill you.
regards, tom lane
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