accumulo-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From William Slacum <>
Subject Re: Performance of table with large number of column families
Date Fri, 09 Nov 2012 16:49:08 GMT
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 <> 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 <
>> 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 <
>>> 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 <>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

View raw message