Re: select e rollback segment

From: Knut Talman <knut.talman_at_mytoys.de>
Date: Wed, 24 Apr 2002 17:02:57 +0200
Message-ID: <3CC6C921.10400@mytoys.de>

Renato wrote:

> the query with a SELECT statement use the rollback segment? I execute a
> query on Oracle 7.3.4 and the programme gave me the error: "snapshoot too
> old: rollback segment NAME too small (ORA 01555)"

Yes, it does. Just imagine you query a large table and fetch the data row by row. It takes some time to do that. Meanwhile another user updates the data you just asked for (you did not lock the rows with your SELECT). Nevertheless you will see the data as it was before the UPDATE, because you started your query earlier. Therefore a rollback segment is used.

Regards,

Knut Received on Wed Apr 24 2002 - 10:02:57 CDT