Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
Hive >> mail # user >> Any Scenarios in which Views impose performance penalties


Copy link to this message
-
Re: Any Scenarios in which Views impose performance penalties
Thanks for the inputs Edward and Ricky.  I did look at the relevant source
code on the version we are using 0.9 and it does not appear there would be
any impact of views on the underlying sql - it does column aliasing and
checks  that the query partition columns match partition columns of the
underlying tables.    Neither would lead to incorrect partition pruning.

2013/8/20 Ricky Saltzer <[EMAIL PROTECTED]>

> My apologies, being on both a Hive and Impala mailing list can be
> confusing ;).
>
>
> On Tue, Aug 20, 2013 at 10:40 PM, Edward Capriolo <[EMAIL PROTECTED]>wrote:
>
>> Views are logical . The view is compiled and has no penalty over the
>> standard query.
>>
>>
>> On Tuesday, August 20, 2013, Ricky Saltzer <[EMAIL PROTECTED]> wrote:
>> > Since this bug was in Impala's query planner, I'm sure Hive is
>> unaffected.
>> >
>> > On Aug 20, 2013 10:15 PM, "Stephen Boesch" <[EMAIL PROTECTED]> wrote:
>> >>
>> >> Thanks v much Ricky.  Is this fixed in hive 0.11 - or going to be
>> later i.e. 0.12?
>> >>
>> >> 2013/8/20 Ricky Saltzer <[EMAIL PROTECTED]>
>> >>>
>> >>> Although this is already fixed in the next and upcoming impala
>> release, you might want to be aware of the following view limitation.
>> >>>
>> >>> https://issues.cloudera.org/browse/IMPALA-495
>> >>>
>> >>> On Aug 20, 2013 7:16 PM, "Stephen Boesch" <[EMAIL PROTECTED]> wrote:
>> >>>>
>> >>>> Views should theoretically not incur performance penalties: they
>> simply represent queries. Are there situtions that things are "not that
>> simple" - i.e. views may actually result in different exeucution plans than
>> the underlying sql?
>> >>>> Additionally, are there views-related bugs that we should be aware
>> of that would limit the occasions that we could use them?
>> >>>> Thanks for the pointers.
>> >>>>
>> >>
>> >
>>
>
>
>
> --
> Ricky Saltzer
> Tools Developer
> http://www.cloudera.com
>
>
>