Re: Postgresql "FIFO" Tables, How-To ?

From: Thomas Kellerer <spam_eater(at)gmx(dot)net>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: Postgresql "FIFO" Tables, How-To ?
Date: 2003-07-17 13:22:48
Message-ID: bf67tb$1hm$1@main.gmane.org
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Tom Lane schrieb:
> Thomas Kellerer <spam_eater(at)gmx(dot)net> writes:
>
>>But isn't that exactly the problem? Once the sequence wraps around how do I
>>know that id=1 is actually later then id=2 without a date column?
>
>
> If you use an int8 sequence column, I doubt you need to worry about
> wraparound. A date column probably hasn't got enough resolution,
> so the other workable approach is to use a timestamp column. Ends up
> costing 8 bytes either way.
>

I'm aware of that, I was referring to Sean's comment:

> The nifty thing about using a wrapping sequence is that the id's are
> sequential across transactions, which correctly maps to the
> progression of time, which obviates the need for relying on any kind
> of a date column for doing syslog message ordering.

If you only use the id, you can't really tell the message ordering by
the ID as id=1 could well be inserted *after* id=2 due to the wrapping
of the sequence

Cheers
Thomas

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