Re: What's the XID?

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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