| From: | "Carlos H(dot) Reimer" <carlosreimer(at)terra(dot)com(dot)br> |
|---|---|
| To: | <pgsql-general(at)postgresql(dot)org> |
| Subject: | XID comparations |
| Date: | 2006-06-13 15:10:26 |
| Message-ID: | PEEPKDFEHHEMKBBFPOOKMELADAAA.carlosreimer@terra.com.br |
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| Lists: | pgsql-general |
Hi,
I would like to understand better the logic to determine when a xid is older
than another one.
As I could understand, the XID is always incremented, never reset. If it is
true, then we can have rows with cmin ranging
from 1 to 4.294.967.295 (2^32-1).
When xid overflows (32 bits) the next one will be 3 (1 and 2 are reserved).
In this case, we could have have lines with cmin 4.294.967.295 and lines
with cmin 3. How are they compared to determine that
rows with cmin 3 are newer than rows with cmin 4.294.967.295?
Thanks in advance,
Reimer
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