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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