Re: What is xmin ? - Mailing list pgsql-general

From Alvaro Herrera
Subject Re: What is xmin ?
Date
Msg-id 20050118145925.GB13418@dcc.uchile.cl
Whole thread Raw
In response to Re: What is xmin ?  (Karsten Hilbert <Karsten.Hilbert@gmx.net>)
List pgsql-general
On Tue, Jan 18, 2005 at 02:43:09PM +0100, Karsten Hilbert wrote:

> XMIN holds the id of the transaction which did the most recent
> change to a row as is visible from within the current
> transaction. Unless it wraps around (is that possible ?) older
> transactions should have XMIN values lower than younger
> transactions.

Yes, it wraps around, that's why modulo arithmetic is used internally to
handle it.  Beyond that, it skips a few (3 or 4) special values just
above zero.

--
Alvaro Herrera (<alvherre[@]dcc.uchile.cl>)
"There was no reply" (Kernel Traffic)

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