Re: What's the XID?

Tom Lane wrote:
> "ivan.hou" <ivan(dot)hou(at)msa(dot)hinet(dot)net> writes:
>> step 1. SELECT datname, age(datfrozenxid) FROM pg_database;
>> --> mydb age:33183
>> step 2. SELECT datname, age(datfrozenxid) FROM pg_database;
>> --> mydb age:33188
>
>> why always increased by 5?
>
> If you do it directly in psql, it increases by 1.
>
>> Postgresql Ver:8.1.3
>> using pgAdminIII Query window
>
> Perhaps you should ask the pgAdmin people what they're doing behind your
> back ...

We first send the query to the database. For each returned column, we
send two queries. The first one gives us the type's name of the column
and the second one gives us the OID of the base type. So, each query
executed with pgAdmin's query tool should increase age(datfrozenxid) by :
1 + (2 * number of columns in the SELECT)

Regards.

--
Guillaume.
http://www.postgresqlfr.org
http://dalibo.com