| From: | Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> |
|---|---|
| To: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: What is xmin ? |
| Date: | 2005-01-18 14:59:25 |
| Message-ID: | 20050118145925.GB13418@dcc.uchile.cl |
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| Lists: | 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[(at)]dcc(dot)uchile(dot)cl>)
"There was no reply" (Kernel Traffic)
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