Re: Interview question
From: Guillermo Alan Bort <cicciuxdba_at_gmail.com>
Date: Fri, 26 Apr 2013 12:10:37 -0300
Message-ID: <CAJ2dSGT-HFZGQ8Kp+3r7ZY=8VC4+0WutA4zV8aO7nK+C361PgQ_at_mail.gmail.com>
Partitioning?
Adding a column and flagging the rows is not the same as removing them. So this is a functional question. If the app supports the use of this column to filter the rows then you would be adding a fast full index scan to the execution of the queries (assuming they are written properly). However, removing them would have a big impact for a limited time and no execution plan would need to change. I would personally go with deleting the records, under the correct circumstances, of course.
Date: Fri, 26 Apr 2013 12:10:37 -0300
Message-ID: <CAJ2dSGT-HFZGQ8Kp+3r7ZY=8VC4+0WutA4zV8aO7nK+C361PgQ_at_mail.gmail.com>
Partitioning?
Adding a column and flagging the rows is not the same as removing them. So this is a functional question. If the app supports the use of this column to filter the rows then you would be adding a fast full index scan to the execution of the queries (assuming they are written properly). However, removing them would have a big impact for a limited time and no execution plan would need to change. I would personally go with deleting the records, under the correct circumstances, of course.
A deeper understanding of the relation between these tables and the reason behind the data duplication would be necessary.
hth
Alan.-
On Fri, Apr 26, 2013 at 10:36 AM, <rajugaru.vij_at_gmail.com> wrote:
> Again back with an interview question.
> Table A has 400 million rows and table b has 1 million rows.
>
> I want to compare table A and Table B and find all the rows available in b
> which are already available in A.
>
> want to remove all those which are available in B from A.
>
> What would be best option? Deleting them or adding a column and flagging
> them?
>
> What's the better option performance wise?
>
> Thanks
> Sent on my BlackBerry® from Vodafone--
> http://www.freelists.org/webpage/oracle-l
>
>
>
-- http://www.freelists.org/webpage/oracle-lReceived on Fri Apr 26 2013 - 17:10:37 CEST