Kevin.Grittner@xxxxxxxxxxxx ("Kevin Grittner") writes:
> Filip Rembia*kowski<plk.zuber@xxxxxxxxx> wrote:
>> 2011/1/19 Charles.Hou <givemeegn@xxxxxxxxx>:
>
>>> " select * from mybook" SQL command also increase the XID ?
>>
>> Yes. Single SELECT is a transaction. Hence, it needs a transaction
>> ID.
>
> No, not in recent versions of PostgreSQL. There's virtual
> transaction ID, too; which is all that's needed unless the
> transaction writes something.
>
> Also, as a fine point, if you use explicit database transactions
> (with BEGIN or START TRANSACTION) then you normally get one XID for
> the entire transaction, unless you use SAVEPOINTs.
Erm, "not *necessarily* in recent versions of PostgreSQL."
A read-only transaction won't consume XIDs, but if you don't expressly
declare it read-only, they're still liable to get eaten...
--
(format nil "~S@~S" "cbbrowne" "gmail.com")
http://www3.sympatico.ca/cbbrowne/lisp.html
Parenthesize to avoid ambiguity.
--
Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
