accumulo-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Josh Elser <>
Subject Re: Abnormal behaviour of custom iterator in getting entries
Date Wed, 17 Jun 2015 15:13:39 GMT

Understood. A few more questions..

How are you passing these IDs to the batch scanner? Are you providing 
individual Ranges for each ID (e.g. `new Range(new Key("row1", "", 
"id1"), true, new Key("row1", "", "id1\x00"), false))`)? Or are you 
providing an entire row (or set of rows) and using the 
fetchColumns(Text,Text) method (or similar) on the BatchScanner?

Are you trying to sum across all rows that you queried? Or is your sum 
per-row? If the former, that is going to cause you problems. The quick 
explanation is that you can't reliably know the tablet boundaries so you 
should try to perform an initial sum, per row. If you want, you can put 
a second iterator "above" the first and do a summation across all rows 
to reduce the amount of data sent to a client. However, if you use a 
BatchScanner, you will still have to perform a final summation at the 

Check out 
for more details on that..

madhvi wrote:
> Hi Josh,
> Sorry, my company policy doesn't allow me to share full source.What we
> are tryng to do is summing over a unique field stored in column
> qualifier for IDs passed to batch scanner.Can u suggest how it can be
> done in accumulo.
> Thanks
> Madhvi
> On Wednesday 17 June 2015 10:32 AM, Josh Elser wrote:
>> You put random values in the family and qualifier? Do I misunderstand
>> you?
>> Also, if you can put up the full source for the iterator, that will be
>> much easier if you need help debugging it. It's hard for us to guess
>> at why your code might not be working as you expect.
>> madhvi wrote:
>>> Hi Josh,
>>> I have changed HashMap to TreeMap which sorts lexicographically and I
>>> have inserted random values in column family and qualifier.Value of
>>> TreeMap in value.
>>> Used scanner and batch scanner but getting results only with scanner.
>>> Thanks
>>> Madhvi
>>> On Tuesday 16 June 2015 08:42 PM, Josh Elser wrote:
>>>> Additionally, you're placing the Value into the ColumnQualifier and
>>>> dropping the ColumnFamily completely. Granted, that may not be a
>>>> problem for the specific data in your table, but it's not going to
>>>> work for any data.
>>>> Christopher wrote:
>>>>> You're iterating over a HashMap. That's not sorted.
>>>>> --
>>>>> Christopher L Tubbs II
>>>>> On Tue, Jun 16, 2015 at 1:58 AM, madhvi<>
>>>>> wrote:
>>>>>> Hi Josh,
>>>>>> Thanks for replying. I will enable remote debugger on my Accumulo
>>>>>> server.
>>>>>> However I am slightly confused with your statement "you are not
>>>>>> returning
>>>>>> your data in sorted order". Can you point the part in my iterator
>>>>>> code which
>>>>>> seems innapropriate and any possible solution for that?
>>>>>> Thanks
>>>>>> Madhvi
>>>>>> On Tuesday 16 June 2015 11:07 AM, Josh Elser wrote:
>>>>>>> //matched the condition and put values to holder map.

View raw message