From: | "ivan(dot)hou" <ivan(dot)hou(at)msa(dot)hinet(dot)net> |
---|---|
To: | pgsql-admin(at)postgresql(dot)org |
Subject: | Re: What's the XID? |
Date: | 2008-01-02 04:52:02 |
Message-ID: | 14573789.post@talk.nabble.com |
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Thread: | |
Lists: | pgsql-admin |
how can i prove that the xid had been increased by 1?
i do a test,
step 1. SELECT datname, age(datfrozenxid) FROM pg_database;
--> mydb age:33183
step 2. SELECT datname, age(datfrozenxid) FROM pg_database;
--> mydb age:33188
step 3. SELECT datname, age(datfrozenxid) FROM pg_database;
--> mydb age:33193
why always increased by 5?
Postgresql Ver:8.1.3
using pgAdminIII Query window
Andrew Sullivan wrote:
>
> On Wed, Dec 26, 2007 at 05:48:14PM -0800, ivan.hou wrote:
>>
>> XID is transcation ID?
>
> Yes.
>
>> so, "select * from mydb" is a transcation?
>
> Yes.
>
>> if i executed "select * from mydb" twice, the XID wil be increased by 2
>
> Yep. Whereas if you did
>
> BEGIN;
> SELECT 1;
> SELECT 1;
> COMMIT;
>
> the xid would be increased by 1.
>
> A
>
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