| From: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
|---|---|
| To: | Jim Nasby <jim(at)nasby(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 17:19:29 |
| Message-ID: | 4DC2DC21.7000505@dunslane.net |
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| Lists: | pgsql-hackers |
On 05/05/2011 01:00 PM, Jim Nasby wrote:
> 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.
No it's not. Instead of storing OLD/NEW, store a base record and a delta
record (an hstore with just the changed fields) for an update. This
saves space and means you only have to calculate what changed once.
cheers
andrew
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