From: | Jim Nasby <jim(at)nasby(dot)net> |
---|---|
To: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
Cc: | Vlad Arkhipov <arhipov(at)dc(dot)baikal(dot)ru>, Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Audit Logs WAS: temporal support patch |
Date: | 2012-08-28 21:06:42 |
Message-ID: | 503D32E2.3030602@nasby.net |
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Lists: | pgsql-hackers |
On 8/28/12 2:51 PM, Pavel Stehule wrote:
>> >The thing I don't like about this is it assumes that time is the best way to
>> >refer to when things changed in a system. Not only is that a bad assumption,
>> >it also means that relating things to history becomes messy.
> On second hand I don't have a problem with some optional counter,
> although I think so database system time is very useful and other
> counters for versioning are not necessary - because in one time I can
> have only one version - it doesn't do versions from rollbacked
> transactions.
What happens if the system clock runs backwards?
What happens if two transactions start in the same microsecond? (And I know for a fact that's possible, because I've seen it).
More importantly, I believe using time to handle recording a versioned history of something is flawed to begin with. You might care about what time a new version was created; but what's far more important is recording the correct ordering of things, and time isn't actually a great way to do that.
Note that no version control systems use time as their primary attribute.
--
Jim C. Nasby, Database Architect jim(at)nasby(dot)net
512.569.9461 (cell) http://jim.nasby.net
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