Re: Interview question
- From: Guillermo Alan Bort <cicciuxdba@xxxxxxxxx>
- To: David Ramírez Reyes <dramirezr@xxxxxxxxx>
- Date: Fri, 26 Apr 2013 14:34:38 -0300
It really depends on the interviewer, but I've found that the most
effective interviews for Sr. level DBAs are designed to find out how the
candidate thinks and approaches problems. It doesn't have to be the same as
the interviewer, but show that the candidate has a firm grasp of the
concepts and the ability to translate those concepts into actual useful
answers. I especially value candidates that admit they don't know the
answer to something and still venture a guess based on what they know
(informing you that it's a guess, of course).
So to that effect, asking an open question like "what would be better:
adding a flag or deleting the records?" could lead to the candidate asking
clarification on the scenario or providing the pors and cons of both
alternatives.
hth
Alan.-
On Fri, Apr 26, 2013 at 1:47 PM, David RamÃrez Reyes
<dramirezr@xxxxxxxxx>wrote:
> The question is not well done, it's like asking what is best, add more
> disk space or delete unused files from a filesystem?, you are asking about
> comparison from apples to pears, removing the records will always be the
> best option (if possible).
>
> A better question would be what is the best way to have both values
> separated (the one in both and the one only in A) from performance
> perspective?, adding a flag?, partitioned table?, partitioned index?,
> both?, materialized view?
>
> Thanks
>
> David RamÃrez Reyes
> Profesión: Padre de Familia
>
>
>
> On 26 April 2013 10:10, Guillermo Alan Bort <cicciuxdba@xxxxxxxxx> wrote:
>
>> 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@xxxxxxxxx> 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 BlackBerryŽ from Vodafone--
>> > //www.freelists.org/webpage/oracle-l
>> >
>> >
>> >
>>
>> --
>> //www.freelists.org/webpage/oracle-l
>>
>>
>>
>
--
//www.freelists.org/webpage/oracle-l
Other related posts:
