| From: | Jim Nasby <jim(at)nasby(dot)net> |
|---|---|
| To: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: VARIANT / ANYTYPE datatype |
| Date: | 2011-05-05 17:00:41 |
| Message-ID: | C99C1182-D167-42F1-BDD8-A48CAFA98F50@nasby.net |
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| Lists: | pgsql-hackers |
On May 4, 2011, at 6:24 PM, Andrew Dunstan wrote:
> I'm far from convinced that storing deltas per column rather than per record is a win anyway. I don't have hard numbers to hand, but my vague recollection is that my tests showed it to be a design that used more space.
It depends on how many fields you're changing in one go and how wide the table is. It's also a PITA to identify what fields actually changed if you're storing everything. In the case of logging, I'd say that what's really needed is a way to store a table record that has an indicator of what fields actually changed (and possibly not storing anything for fields that didn't change). That table record would need to also deal with changes to the underlying table structure.
--
Jim C. Nasby, Database Architect jim(at)nasby(dot)net
512.569.9461 (cell) http://jim.nasby.net
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