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Posted to user@accumulo.apache.org by Marc Reichman <mr...@pixelforensics.com> on 2013/08/21 16:00:24 UTC
Filtering on column qualifier
I have some data stored in Accumulo with some scores stored as column
qualifiers (there was an older thread about this). I would like to find a
way to do thresholding when retrieving the data without retrieving it all
and then manually filtering out items below my threshold.
I know I can "fetch" column qualifiers which are exact.
I've seen the ColumnQualifierFilter, which I assume is what's in play when
I fetch qualifiers. Is there a reasonable pattern to extend this and try to
use it as a scan iterator so I can do things like "greater than" a value
which will be interpreted as a Double vs. the string equality going on now?
Thanks,
Marc
Re: Filtering on column qualifier
Posted by John Vines <vi...@apache.org>.
Nope, it's just a custom Filter, which is a type of iterator. You can
attach iterators to run on a scanner, you just need to make sure you deploy
the jar with the custom iterator to all of the tservers.
On Wed, Aug 21, 2013 at 7:58 PM, Slater, David M.
<Da...@jhuapl.edu>wrote:
> Would this require extending the BatchScanner as well to make use of the
> extended ColumnQualifierFilter, or could this be done with an unmodified
> BatchScanner?****
>
> ** **
>
> *From:* John Vines [mailto:vines@apache.org]
> *Sent:* Wednesday, August 21, 2013 10:49 AM
> *To:* user@accumulo.apache.org
> *Subject:* Re: Filtering on column qualifier****
>
> ** **
>
> There's no way to extend the ColumnQualietyFilter via configuration, but
> it sounds like you are on top of it. You just need to extend the class,
> possibly copy a bit of code, and change the equality check to a compareTo
> after converting the Strings to Doubles.****
>
> ** **
>
> On Wed, Aug 21, 2013 at 10:00 AM, Marc Reichman <
> mreichman@pixelforensics.com> wrote:****
>
> I have some data stored in Accumulo with some scores stored as column
> qualifiers (there was an older thread about this). I would like to find a
> way to do thresholding when retrieving the data without retrieving it all
> and then manually filtering out items below my threshold.****
>
> ** **
>
> I know I can "fetch" column qualifiers which are exact.****
>
> ** **
>
> I've seen the ColumnQualifierFilter, which I assume is what's in play when
> I fetch qualifiers. Is there a reasonable pattern to extend this and try to
> use it as a scan iterator so I can do things like "greater than" a value
> which will be interpreted as a Double vs. the string equality going on now?
> ****
>
> ** **
>
> Thanks,****
>
> Marc****
>
> ** **
>
RE: Filtering on column qualifier
Posted by "Slater, David M." <Da...@jhuapl.edu>.
Would this require extending the BatchScanner as well to make use of the extended ColumnQualifierFilter, or could this be done with an unmodified BatchScanner?
From: John Vines [mailto:vines@apache.org]
Sent: Wednesday, August 21, 2013 10:49 AM
To: user@accumulo.apache.org
Subject: Re: Filtering on column qualifier
There's no way to extend the ColumnQualietyFilter via configuration, but it sounds like you are on top of it. You just need to extend the class, possibly copy a bit of code, and change the equality check to a compareTo after converting the Strings to Doubles.
On Wed, Aug 21, 2013 at 10:00 AM, Marc Reichman <mr...@pixelforensics.com>> wrote:
I have some data stored in Accumulo with some scores stored as column qualifiers (there was an older thread about this). I would like to find a way to do thresholding when retrieving the data without retrieving it all and then manually filtering out items below my threshold.
I know I can "fetch" column qualifiers which are exact.
I've seen the ColumnQualifierFilter, which I assume is what's in play when I fetch qualifiers. Is there a reasonable pattern to extend this and try to use it as a scan iterator so I can do things like "greater than" a value which will be interpreted as a Double vs. the string equality going on now?
Thanks,
Marc
Re: Filtering on column qualifier
Posted by Marc Reichman <mr...@pixelforensics.com>.
I apologize for my dense-ness, but could you walk me through this? Is there
some form of existing scan iterator which interprets groovy? Or is this
something I would build?
On Thu, Aug 22, 2013 at 12:10 PM, David Medinets
<da...@gmail.com>wrote:
> The advantage is that you'd only write the iterator once and deploy it to
> the cluster. Then the groovy snippet changes its behavior. You'd save
> passing the data to your client code, but more work would be done by the
> accumulo cluster.
>
>
> On Thu, Aug 22, 2013 at 12:33 PM, Marc Reichman <
> mreichman@pixelforensics.com> wrote:
>
>> I haven't considered that. Would that allow me to specify it in the
>> client-side code and not worry about spreading JARs around? It is a very
>> basic need, in my scan iterator loop right now is:
>>
>> String matchScoreString = key.getColumnQualifier().toString();
>> Double score = Double.parseDouble(matchScoreString);
>>
>> if (threshold != null && threshold > score) {
>> // TODO: figure out if this is possible to do via
>> data-local scan iterator
>> continue;
>> }
>>
>> What is the pattern for including a groovy snippet for a scan iterator?
>>
>>
>> On Thu, Aug 22, 2013 at 11:16 AM, David Medinets <
>> david.medinets@gmail.com> wrote:
>>
>>> Have you thought of writing a filter class that takes some bit of groovy
>>> for execution inside the accept method, depending on how efficient you need
>>> to be and how changeable your constraints are.
>>>
>>>
>>> On Thu, Aug 22, 2013 at 10:19 AM, Marc Reichman <
>>> mreichman@pixelforensics.com> wrote:
>>>
>>>> Extending looked like a bit of a boondoggle, because all of the useful
>>>> fields in the class are private, not protected. I also ran into another
>>>> architectural question, how does one pass a value (a-la constructor) into
>>>> one of these classes? If I'm going to use this to filter based on a
>>>> threshold, I'd need to pass that threshold in somehow.
>>>>
>>>>
>>>>
>>>>
>>>> On Wed, Aug 21, 2013 at 9:49 AM, John Vines <vi...@apache.org> wrote:
>>>>
>>>>> There's no way to extend the ColumnQualietyFilter via configuration,
>>>>> but it sounds like you are on top of it. You just need to extend the class,
>>>>> possibly copy a bit of code, and change the equality check to a compareTo
>>>>> after converting the Strings to Doubles.
>>>>>
>>>>>
>>>>> On Wed, Aug 21, 2013 at 10:00 AM, Marc Reichman <
>>>>> mreichman@pixelforensics.com> wrote:
>>>>>
>>>>>> I have some data stored in Accumulo with some scores stored as column
>>>>>> qualifiers (there was an older thread about this). I would like to find a
>>>>>> way to do thresholding when retrieving the data without retrieving it all
>>>>>> and then manually filtering out items below my threshold.
>>>>>>
>>>>>> I know I can "fetch" column qualifiers which are exact.
>>>>>>
>>>>>> I've seen the ColumnQualifierFilter, which I assume is what's in play
>>>>>> when I fetch qualifiers. Is there a reasonable pattern to extend this and
>>>>>> try to use it as a scan iterator so I can do things like "greater than" a
>>>>>> value which will be interpreted as a Double vs. the string equality going
>>>>>> on now?
>>>>>>
>>>>>> Thanks,
>>>>>> Marc
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>
Re: Filtering on column qualifier
Posted by John Vines <vi...@apache.org>.
You don't need to write a special language to make it configurable. You can
pass configurations to iterators (and Filters) via IteratorSettings, which
then get tossed into the options on seek. You may need to extend seek to
get that information out though.
On Thu, Aug 22, 2013 at 3:09 PM, John Stoneham <ly...@lyrically.net> wrote:
> We've done similar with Clojure as a lark, passing in custom map or filter
> functions. But we've never deployed it because of the security risk of
> running arbitrary user code on tservers, unsandboxed.
>
>
> On Thu, Aug 22, 2013 at 1:10 PM, David Medinets <da...@gmail.com>wrote:
>
>> The advantage is that you'd only write the iterator once and deploy it to
>> the cluster. Then the groovy snippet changes its behavior. You'd save
>> passing the data to your client code, but more work would be done by the
>> accumulo cluster.
>>
>>
>> On Thu, Aug 22, 2013 at 12:33 PM, Marc Reichman <
>> mreichman@pixelforensics.com> wrote:
>>
>>> I haven't considered that. Would that allow me to specify it in the
>>> client-side code and not worry about spreading JARs around? It is a very
>>> basic need, in my scan iterator loop right now is:
>>>
>>> String matchScoreString =
>>> key.getColumnQualifier().toString();
>>> Double score = Double.parseDouble(matchScoreString);
>>>
>>> if (threshold != null && threshold > score) {
>>> // TODO: figure out if this is possible to do via
>>> data-local scan iterator
>>> continue;
>>> }
>>>
>>> What is the pattern for including a groovy snippet for a scan iterator?
>>>
>>>
>>> On Thu, Aug 22, 2013 at 11:16 AM, David Medinets <
>>> david.medinets@gmail.com> wrote:
>>>
>>>> Have you thought of writing a filter class that takes some bit of
>>>> groovy for execution inside the accept method, depending on how efficient
>>>> you need to be and how changeable your constraints are.
>>>>
>>>>
>>>> On Thu, Aug 22, 2013 at 10:19 AM, Marc Reichman <
>>>> mreichman@pixelforensics.com> wrote:
>>>>
>>>>> Extending looked like a bit of a boondoggle, because all of the useful
>>>>> fields in the class are private, not protected. I also ran into another
>>>>> architectural question, how does one pass a value (a-la constructor) into
>>>>> one of these classes? If I'm going to use this to filter based on a
>>>>> threshold, I'd need to pass that threshold in somehow.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Aug 21, 2013 at 9:49 AM, John Vines <vi...@apache.org> wrote:
>>>>>
>>>>>> There's no way to extend the ColumnQualietyFilter via configuration,
>>>>>> but it sounds like you are on top of it. You just need to extend the class,
>>>>>> possibly copy a bit of code, and change the equality check to a compareTo
>>>>>> after converting the Strings to Doubles.
>>>>>>
>>>>>>
>>>>>> On Wed, Aug 21, 2013 at 10:00 AM, Marc Reichman <
>>>>>> mreichman@pixelforensics.com> wrote:
>>>>>>
>>>>>>> I have some data stored in Accumulo with some scores stored as
>>>>>>> column qualifiers (there was an older thread about this). I would like to
>>>>>>> find a way to do thresholding when retrieving the data without retrieving
>>>>>>> it all and then manually filtering out items below my threshold.
>>>>>>>
>>>>>>> I know I can "fetch" column qualifiers which are exact.
>>>>>>>
>>>>>>> I've seen the ColumnQualifierFilter, which I assume is what's in
>>>>>>> play when I fetch qualifiers. Is there a reasonable pattern to extend this
>>>>>>> and try to use it as a scan iterator so I can do things like "greater than"
>>>>>>> a value which will be interpreted as a Double vs. the string equality going
>>>>>>> on now?
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Marc
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
>
> --
> John Stoneham
> lyric@lyrically.net
>
Re: Filtering on column qualifier
Posted by John Stoneham <ly...@lyrically.net>.
We've done similar with Clojure as a lark, passing in custom map or filter
functions. But we've never deployed it because of the security risk of
running arbitrary user code on tservers, unsandboxed.
On Thu, Aug 22, 2013 at 1:10 PM, David Medinets <da...@gmail.com>wrote:
> The advantage is that you'd only write the iterator once and deploy it to
> the cluster. Then the groovy snippet changes its behavior. You'd save
> passing the data to your client code, but more work would be done by the
> accumulo cluster.
>
>
> On Thu, Aug 22, 2013 at 12:33 PM, Marc Reichman <
> mreichman@pixelforensics.com> wrote:
>
>> I haven't considered that. Would that allow me to specify it in the
>> client-side code and not worry about spreading JARs around? It is a very
>> basic need, in my scan iterator loop right now is:
>>
>> String matchScoreString = key.getColumnQualifier().toString();
>> Double score = Double.parseDouble(matchScoreString);
>>
>> if (threshold != null && threshold > score) {
>> // TODO: figure out if this is possible to do via
>> data-local scan iterator
>> continue;
>> }
>>
>> What is the pattern for including a groovy snippet for a scan iterator?
>>
>>
>> On Thu, Aug 22, 2013 at 11:16 AM, David Medinets <
>> david.medinets@gmail.com> wrote:
>>
>>> Have you thought of writing a filter class that takes some bit of groovy
>>> for execution inside the accept method, depending on how efficient you need
>>> to be and how changeable your constraints are.
>>>
>>>
>>> On Thu, Aug 22, 2013 at 10:19 AM, Marc Reichman <
>>> mreichman@pixelforensics.com> wrote:
>>>
>>>> Extending looked like a bit of a boondoggle, because all of the useful
>>>> fields in the class are private, not protected. I also ran into another
>>>> architectural question, how does one pass a value (a-la constructor) into
>>>> one of these classes? If I'm going to use this to filter based on a
>>>> threshold, I'd need to pass that threshold in somehow.
>>>>
>>>>
>>>>
>>>>
>>>> On Wed, Aug 21, 2013 at 9:49 AM, John Vines <vi...@apache.org> wrote:
>>>>
>>>>> There's no way to extend the ColumnQualietyFilter via configuration,
>>>>> but it sounds like you are on top of it. You just need to extend the class,
>>>>> possibly copy a bit of code, and change the equality check to a compareTo
>>>>> after converting the Strings to Doubles.
>>>>>
>>>>>
>>>>> On Wed, Aug 21, 2013 at 10:00 AM, Marc Reichman <
>>>>> mreichman@pixelforensics.com> wrote:
>>>>>
>>>>>> I have some data stored in Accumulo with some scores stored as column
>>>>>> qualifiers (there was an older thread about this). I would like to find a
>>>>>> way to do thresholding when retrieving the data without retrieving it all
>>>>>> and then manually filtering out items below my threshold.
>>>>>>
>>>>>> I know I can "fetch" column qualifiers which are exact.
>>>>>>
>>>>>> I've seen the ColumnQualifierFilter, which I assume is what's in play
>>>>>> when I fetch qualifiers. Is there a reasonable pattern to extend this and
>>>>>> try to use it as a scan iterator so I can do things like "greater than" a
>>>>>> value which will be interpreted as a Double vs. the string equality going
>>>>>> on now?
>>>>>>
>>>>>> Thanks,
>>>>>> Marc
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>
--
John Stoneham
lyric@lyrically.net
Re: Filtering on column qualifier
Posted by David Medinets <da...@gmail.com>.
The advantage is that you'd only write the iterator once and deploy it to
the cluster. Then the groovy snippet changes its behavior. You'd save
passing the data to your client code, but more work would be done by the
accumulo cluster.
On Thu, Aug 22, 2013 at 12:33 PM, Marc Reichman <
mreichman@pixelforensics.com> wrote:
> I haven't considered that. Would that allow me to specify it in the
> client-side code and not worry about spreading JARs around? It is a very
> basic need, in my scan iterator loop right now is:
>
> String matchScoreString = key.getColumnQualifier().toString();
> Double score = Double.parseDouble(matchScoreString);
>
> if (threshold != null && threshold > score) {
> // TODO: figure out if this is possible to do via
> data-local scan iterator
> continue;
> }
>
> What is the pattern for including a groovy snippet for a scan iterator?
>
>
> On Thu, Aug 22, 2013 at 11:16 AM, David Medinets <david.medinets@gmail.com
> > wrote:
>
>> Have you thought of writing a filter class that takes some bit of groovy
>> for execution inside the accept method, depending on how efficient you need
>> to be and how changeable your constraints are.
>>
>>
>> On Thu, Aug 22, 2013 at 10:19 AM, Marc Reichman <
>> mreichman@pixelforensics.com> wrote:
>>
>>> Extending looked like a bit of a boondoggle, because all of the useful
>>> fields in the class are private, not protected. I also ran into another
>>> architectural question, how does one pass a value (a-la constructor) into
>>> one of these classes? If I'm going to use this to filter based on a
>>> threshold, I'd need to pass that threshold in somehow.
>>>
>>>
>>>
>>>
>>> On Wed, Aug 21, 2013 at 9:49 AM, John Vines <vi...@apache.org> wrote:
>>>
>>>> There's no way to extend the ColumnQualietyFilter via configuration,
>>>> but it sounds like you are on top of it. You just need to extend the class,
>>>> possibly copy a bit of code, and change the equality check to a compareTo
>>>> after converting the Strings to Doubles.
>>>>
>>>>
>>>> On Wed, Aug 21, 2013 at 10:00 AM, Marc Reichman <
>>>> mreichman@pixelforensics.com> wrote:
>>>>
>>>>> I have some data stored in Accumulo with some scores stored as column
>>>>> qualifiers (there was an older thread about this). I would like to find a
>>>>> way to do thresholding when retrieving the data without retrieving it all
>>>>> and then manually filtering out items below my threshold.
>>>>>
>>>>> I know I can "fetch" column qualifiers which are exact.
>>>>>
>>>>> I've seen the ColumnQualifierFilter, which I assume is what's in play
>>>>> when I fetch qualifiers. Is there a reasonable pattern to extend this and
>>>>> try to use it as a scan iterator so I can do things like "greater than" a
>>>>> value which will be interpreted as a Double vs. the string equality going
>>>>> on now?
>>>>>
>>>>> Thanks,
>>>>> Marc
>>>>>
>>>>
>>>>
>>>
>>
>
Re: Filtering on column qualifier
Posted by Marc Reichman <mr...@pixelforensics.com>.
I haven't considered that. Would that allow me to specify it in the
client-side code and not worry about spreading JARs around? It is a very
basic need, in my scan iterator loop right now is:
String matchScoreString = key.getColumnQualifier().toString();
Double score = Double.parseDouble(matchScoreString);
if (threshold != null && threshold > score) {
// TODO: figure out if this is possible to do via
data-local scan iterator
continue;
}
What is the pattern for including a groovy snippet for a scan iterator?
On Thu, Aug 22, 2013 at 11:16 AM, David Medinets
<da...@gmail.com>wrote:
> Have you thought of writing a filter class that takes some bit of groovy
> for execution inside the accept method, depending on how efficient you need
> to be and how changeable your constraints are.
>
>
> On Thu, Aug 22, 2013 at 10:19 AM, Marc Reichman <
> mreichman@pixelforensics.com> wrote:
>
>> Extending looked like a bit of a boondoggle, because all of the useful
>> fields in the class are private, not protected. I also ran into another
>> architectural question, how does one pass a value (a-la constructor) into
>> one of these classes? If I'm going to use this to filter based on a
>> threshold, I'd need to pass that threshold in somehow.
>>
>>
>>
>>
>> On Wed, Aug 21, 2013 at 9:49 AM, John Vines <vi...@apache.org> wrote:
>>
>>> There's no way to extend the ColumnQualietyFilter via configuration, but
>>> it sounds like you are on top of it. You just need to extend the class,
>>> possibly copy a bit of code, and change the equality check to a compareTo
>>> after converting the Strings to Doubles.
>>>
>>>
>>> On Wed, Aug 21, 2013 at 10:00 AM, Marc Reichman <
>>> mreichman@pixelforensics.com> wrote:
>>>
>>>> I have some data stored in Accumulo with some scores stored as column
>>>> qualifiers (there was an older thread about this). I would like to find a
>>>> way to do thresholding when retrieving the data without retrieving it all
>>>> and then manually filtering out items below my threshold.
>>>>
>>>> I know I can "fetch" column qualifiers which are exact.
>>>>
>>>> I've seen the ColumnQualifierFilter, which I assume is what's in play
>>>> when I fetch qualifiers. Is there a reasonable pattern to extend this and
>>>> try to use it as a scan iterator so I can do things like "greater than" a
>>>> value which will be interpreted as a Double vs. the string equality going
>>>> on now?
>>>>
>>>> Thanks,
>>>> Marc
>>>>
>>>
>>>
>>
>
Re: Filtering on column qualifier
Posted by David Medinets <da...@gmail.com>.
Have you thought of writing a filter class that takes some bit of groovy
for execution inside the accept method, depending on how efficient you need
to be and how changeable your constraints are.
On Thu, Aug 22, 2013 at 10:19 AM, Marc Reichman <
mreichman@pixelforensics.com> wrote:
> Extending looked like a bit of a boondoggle, because all of the useful
> fields in the class are private, not protected. I also ran into another
> architectural question, how does one pass a value (a-la constructor) into
> one of these classes? If I'm going to use this to filter based on a
> threshold, I'd need to pass that threshold in somehow.
>
>
>
>
> On Wed, Aug 21, 2013 at 9:49 AM, John Vines <vi...@apache.org> wrote:
>
>> There's no way to extend the ColumnQualietyFilter via configuration, but
>> it sounds like you are on top of it. You just need to extend the class,
>> possibly copy a bit of code, and change the equality check to a compareTo
>> after converting the Strings to Doubles.
>>
>>
>> On Wed, Aug 21, 2013 at 10:00 AM, Marc Reichman <
>> mreichman@pixelforensics.com> wrote:
>>
>>> I have some data stored in Accumulo with some scores stored as column
>>> qualifiers (there was an older thread about this). I would like to find a
>>> way to do thresholding when retrieving the data without retrieving it all
>>> and then manually filtering out items below my threshold.
>>>
>>> I know I can "fetch" column qualifiers which are exact.
>>>
>>> I've seen the ColumnQualifierFilter, which I assume is what's in play
>>> when I fetch qualifiers. Is there a reasonable pattern to extend this and
>>> try to use it as a scan iterator so I can do things like "greater than" a
>>> value which will be interpreted as a Double vs. the string equality going
>>> on now?
>>>
>>> Thanks,
>>> Marc
>>>
>>
>>
>
Re: Filtering on column qualifier
Posted by Marc Reichman <mr...@pixelforensics.com>.
Extending looked like a bit of a boondoggle, because all of the useful
fields in the class are private, not protected. I also ran into another
architectural question, how does one pass a value (a-la constructor) into
one of these classes? If I'm going to use this to filter based on a
threshold, I'd need to pass that threshold in somehow.
On Wed, Aug 21, 2013 at 9:49 AM, John Vines <vi...@apache.org> wrote:
> There's no way to extend the ColumnQualietyFilter via configuration, but
> it sounds like you are on top of it. You just need to extend the class,
> possibly copy a bit of code, and change the equality check to a compareTo
> after converting the Strings to Doubles.
>
>
> On Wed, Aug 21, 2013 at 10:00 AM, Marc Reichman <
> mreichman@pixelforensics.com> wrote:
>
>> I have some data stored in Accumulo with some scores stored as column
>> qualifiers (there was an older thread about this). I would like to find a
>> way to do thresholding when retrieving the data without retrieving it all
>> and then manually filtering out items below my threshold.
>>
>> I know I can "fetch" column qualifiers which are exact.
>>
>> I've seen the ColumnQualifierFilter, which I assume is what's in play
>> when I fetch qualifiers. Is there a reasonable pattern to extend this and
>> try to use it as a scan iterator so I can do things like "greater than" a
>> value which will be interpreted as a Double vs. the string equality going
>> on now?
>>
>> Thanks,
>> Marc
>>
>
>
Re: Filtering on column qualifier
Posted by John Vines <vi...@apache.org>.
There's no way to extend the ColumnQualietyFilter via configuration, but it
sounds like you are on top of it. You just need to extend the class,
possibly copy a bit of code, and change the equality check to a compareTo
after converting the Strings to Doubles.
On Wed, Aug 21, 2013 at 10:00 AM, Marc Reichman <
mreichman@pixelforensics.com> wrote:
> I have some data stored in Accumulo with some scores stored as column
> qualifiers (there was an older thread about this). I would like to find a
> way to do thresholding when retrieving the data without retrieving it all
> and then manually filtering out items below my threshold.
>
> I know I can "fetch" column qualifiers which are exact.
>
> I've seen the ColumnQualifierFilter, which I assume is what's in play when
> I fetch qualifiers. Is there a reasonable pattern to extend this and try to
> use it as a scan iterator so I can do things like "greater than" a value
> which will be interpreted as a Double vs. the string equality going on now?
>
> Thanks,
> Marc
>