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From Vrushali C <vrush...@ymail.com>
Subject Re: scan filter: how to ignore everything with a prefix except one particular column with that prefix
Date Thu, 05 Jun 2014 22:04:07 GMT
Thanks Ted! Using that regex comparator helped me resolve this. Appreciate it very much! 


On Thursday, June 5, 2014 2:23 PM, Ted Yu <yuzhihong@gmail.com> wrote:
 


Or, you can use RegexStringComparator.

Here is a regex string, in Java, that matches columns with prefix c! except
column called c!someName :

"^c\\!((?!someName).)*$"

Cheers



On Thu, Jun 5, 2014 at 1:26 PM, Ted Yu <yuzhihong@gmail.com> wrote:

> One option is to write your own Comparator (similar to BinaryPrefixComparator
> in essence) that treats the known column name specially.
>
> Cheers
>
>
> On Thu, Jun 5, 2014 at 12:52 PM, Vrushali C <vrushali@ymail.com> wrote:
>
>>
>>
>> Hi
>> Is there a way to do this kind of filtering : In my scan, I want to
>> retrieve all columns except for columns starting with a certain prefix. But
>> within that set of columns being ignored, I have one known column name that
>> I want to retrieve but ignore the rest. The reason is that columns with
>> this prefix have a lot of data and I am not interested in everything EXCEPT
>> one of those.
>>
>> So for ignoring the columns with a certain prefix in the scan, I am doing
>> something like
>> filters.addFilter(
>>      new QualifierFilter(CompareFilter.CompareOp.NOT_EQUAL,
>>         new BinaryPrefixComparator(
>>                 Bytes.add(Bytes.toBytes("c!"), Constants.SEP_BYTES))))
>>
>> Which works. But what I also want to add, is something like this
>>
>> filters.addFilter(
>>      new QualifierFilter(CompareFilter.CompareOp.EQUAL,
>>         new BinaryPrefixComparator(
>>                 Bytes.add(Bytes.toBytes("c!someName"),
>> Constants.SEP_BYTES))))
>>
>> I realize both filters are contradictory to each other, so how do I
>> achieve this?
>>
>> thanks
>> Vrushali
>>
>
>
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