| From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
|---|---|
| To: | ????????? <sheepjxx(at)gmail(dot)com> |
| Cc: | Postgres General Postgres General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: How does PostgreSQL recognise "deleted" tuples by using xmax ? |
| Date: | 2009-10-27 07:38:14 |
| Message-ID: | 20091027073813.GA22746@svana.org |
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| Thread: | |
| Lists: | pgsql-general |
On Tue, Oct 27, 2009 at 03:55:39PM +1100, ????????? wrote:
> How does PostgreSQL recognise "deleted" tuples by using xmax ?
xmax is the ID of the transaction that deleted the row. So if you are
in a transaction that sees that transaction as commited, it has been
deleted (from your point of view). If from your point of view that
transaction is aborted, it has not been deleted. If that transaction is
not finished yet, you have to wait.
Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Please line up in a tree and maintain the heap invariant while
> boarding. Thank you for flying nlogn airlines.
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