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Hive, mail # user - Optimizing ORC Sorting - Replace two level Partitions with one?


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John Omernik 2013-08-10, 15:56
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Nitin Pawar 2013-08-10, 16:34
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Edward Capriolo 2013-08-10, 16:39
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Nitin Pawar 2013-08-10, 16:46
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Re: Optimizing ORC Sorting - Replace two level Partitions with one?
John Omernik 2013-08-10, 16:58
One issue with the bucketing is that the number of sources on any given day
is dynamic. On some days it's 4, others it's 14 and it's also constantly
changing.  I am hoping to use some of the features of the ORC files to
almost make virtual partitions, but apparently I am going to run into
issues either way.

On another note, is there a limit to hive and partitions? I am hovering
around 10k partitions on one table right now. It's still working, but some
metadata operations can take a long time. The Sub-Partitions are going to
hurt me here going forward I am guessing, so it may be worth flattening out
to only days, even at the expense of read queries... thoughts?

On Sat, Aug 10, 2013 at 11:46 AM, Nitin Pawar <[EMAIL PROTECTED]>wrote:

> Agree with Edward,
>
> whole purpose of bucketing for me is to prune the data in where clause.
> Else it totally defeats the purpose of splitting data into finite number of
> identifiable distributions to improve the performance.
>
> But is my understanding correct that it  does help in reducing the number
> of sub partitions we create at the bottom of table can be limited if we
> identify the pattern does not exceed a finite number of values on that
> partitions? (even if it cross this limit bucketting does take care of it
> upto some volume)
>
>
> On Sat, Aug 10, 2013 at 10:09 PM, Edward Capriolo <[EMAIL PROTECTED]>wrote:
>
>> So there is one thing to be really carefully about bucketing. Say you
>> bucket a table into 10 buckets, select with where does not actually prune
>> the input buckets so many queries scan all the buckets.
>>
>>
>> On Sat, Aug 10, 2013 at 12:34 PM, Nitin Pawar <[EMAIL PROTECTED]>wrote:
>>
>>> will bucketing help? if you know finite # partiotions ?
>>>
>>>
>>> On Sat, Aug 10, 2013 at 9:26 PM, John Omernik <[EMAIL PROTECTED]> wrote:
>>>
>>>> I have a table that currently uses RC files and has two levels of
>>>> partitions.  day and source.  The table is first partitioned by day, then
>>>> within each day there are 6-15 source partitions.  This makes for a lot of
>>>> crazy partitions and was wondering if there'd be a way to optimize this
>>>> with ORC files and some sorting.
>>>>
>>>> Specifically, would there be a way in a new table to make source a
>>>> field (removing the partition)and somehow, as I am inserting into this new
>>>> setup sort by source in such a way that will help separate the
>>>> files/indexes in a way that gives me almost the same performance as ORC
>>>> with the two level partitions?  Just trying to optimize here and curious
>>>> what people think.
>>>>
>>>> John
>>>>
>>>
>>>
>>>
>>> --
>>> Nitin Pawar
>>>
>>
>>
>
>
> --
> Nitin Pawar
>
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Edward Capriolo 2013-08-10, 17:19
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John Omernik 2013-08-10, 17:35
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Nitin Pawar 2013-08-10, 18:33