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Accumulo >> mail # user >> Performance of table with large number of column families

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Re: Performance of table with large number of column families
Failed to answer the original question - 15 tablet servers, 32
On Fri, Nov 9, 2012 at 11:52 AM, Anthony Fox <[EMAIL PROTECTED]> wrote:

> I've tried a number of different settings of table.split.threshold.  I
> started at 1G and bumped it down to 128M and the cf scan is still ~30
> seconds for both.  I've also used less rows - 00000 to 99999 and still see
> similar performance numbers.  I thought the column family bloom filter
> would help deal with large row space but sparsely populated column space.
>  Is that correct?
> On Fri, Nov 9, 2012 at 11:49 AM, William Slacum <
>> I'm more inclined to believe it's because you have to search across 10M
>> different rows to find any given column family, since they're randomly, and
>> possibly uniformly, distributed. How many tablets are you searching across?
>> On Fri, Nov 9, 2012 at 11:45 AM, Anthony Fox <[EMAIL PROTECTED]>wrote:
>>> Yes, there are 10M possible partitions.  I do not have a hash from value
>>> to partition, the data is essentially randomly balanced across all the
>>> tablets.  Unlike the bloom filter and intersecting iterator examples, I do
>>> not have locality groups turned on and I have data in the cq and the value
>>> for both index entries and record entries.  Could this be the issue?  Each
>>> record entry has approximately 30 column qualifiers with data in the value
>>> for each.
>>> On Fri, Nov 9, 2012 at 11:41 AM, William Slacum <
>>> [EMAIL PROTECTED]> wrote:
>>>> I guess assuming you have 10M possible partitions, if you're using a
>>>> relatively uniform hash to generate your IDs, you'll average about 2 per
>>>> partition. Do you have any index for term/value to partition? This will
>>>> help you narrow down your search space to a subset of your partitions.
>>>> On Fri, Nov 9, 2012 at 11:39 AM, William Slacum <
>>>> [EMAIL PROTECTED]> wrote:
>>>>> That shouldn't be a huge issue. How many rows/partitions do you have?
>>>>> How many do you have to scan to find the specific column family/doc id you
>>>>> want?
>>>>> On Fri, Nov 9, 2012 at 11:26 AM, Anthony Fox <[EMAIL PROTECTED]>wrote:
>>>>>> I have a table set up to use the intersecting iterator pattern.  The
>>>>>> table has about 20M records which leads to 20M column families for the
>>>>>> data section - 1 unique column family per record.  The index section of
>>>>>> the table is not quite as large as the data section.  The rowkey is a
>>>>>> random padded integer partition between 0000000 and 9999999.  I turned
>>>>>> bloom filters on and used the ColumnFamilyFunctor to get performant
>>>>>> column family scans without specifying a range like in the bloom filter
>>>>>> examples in the README.  However, my column family scans (without any
>>>>>> custom iterator) are still fairly slow - ~30 seconds for a column family
>>>>>> batch scan of one record. I've also tried RowFunctor but I see similar
>>>>>> performance.  Can anyone shed any light on the performance metrics I'm
>>>>>> seeing?
>>>>>> Thanks,
>>>>>> Anthony