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HBase, mail # user - Schema design for filters


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Re: Schema design for filters
Otis Gospodnetic 2013-06-28, 18:34
Kristoffer,

You could also consider using something other than HBase, something
that supports "secondary indices", like anything that is Lucene based
- Solr and ElasticSearch for example.  We recently compared how we
aggregate data in HBase (see my signature) and how we would do it if
we were to use Solr (or ElasticSearch), and so far things look better
in Solr for our use case.  And our use case involves a lot of
filtering, slicing and dicing..... something to consider...

Otis
--
Solr & ElasticSearch Support -- http://sematext.com/
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On Fri, Jun 28, 2013 at 5:24 AM, Kristoffer Sjögren <[EMAIL PROTECTED]> wrote:
> Interesting. Im actually building something similar.
>
> A fullblown SQL implementation is bit overkill for my particular usecase
> and the query API is the final piece to the puzzle. But ill definitely have
> a look for some inspiration.
>
> Thanks!
>
>
>
> On Fri, Jun 28, 2013 at 3:55 AM, James Taylor <[EMAIL PROTECTED]>wrote:
>
>> Hi Kristoffer,
>> Have you had a look at Phoenix (https://github.com/forcedotcom/phoenix)?
>> You could model your schema much like an O/R mapper and issue SQL queries
>> through Phoenix for your filtering.
>>
>> James
>> @JamesPlusPlus
>> http://phoenix-hbase.blogspot.com
>>
>> On Jun 27, 2013, at 4:39 PM, "Kristoffer Sjögren" <[EMAIL PROTECTED]>
>> wrote:
>>
>> > Thanks for your help Mike. Much appreciated.
>> >
>> > I dont store rows/columns in JSON format. The schema is exactly that of a
>> > specific java class, where the rowkey is a unique object identifier with
>> > the class type encoded into it. Columns are the field names of the class
>> > and the values are that of the object instance.
>> >
>> > Did think about coprocessors but the schema is discovered a runtime and I
>> > cant hard code it.
>> >
>> > However, I still believe that filters might work. Had a look
>> > at SingleColumnValueFilter and this filter is be able to target specific
>> > column qualifiers with specific WritableByteArrayComparables.
>> >
>> > But list comparators are still missing... So I guess the only way is to
>> > write these comparators?
>> >
>> > Do you follow my reasoning? Will it work?
>> >
>> >
>> >
>> >
>> > On Fri, Jun 28, 2013 at 12:58 AM, Michael Segel
>> > <[EMAIL PROTECTED]>wrote:
>> >
>> >> Ok...
>> >>
>> >> If you want to do type checking and schema enforcement...
>> >>
>> >> You will need to do this as a coprocessor.
>> >>
>> >> The quick and dirty way... (Not recommended) would be to hard code the
>> >> schema in to the co-processor code.)
>> >>
>> >> A better way... at start up, load up ZK to manage the set of known table
>> >> schemas which would be a map of column qualifier to data type.
>> >> (If JSON then you need to do a separate lookup to get the records
>> schema)
>> >>
>> >> Then a single java class that does the look up and then handles the
>> known
>> >> data type comparators.
>> >>
>> >> Does this make sense?
>> >> (Sorry, kinda was thinking this out as I typed the response. But it
>> should
>> >> work )
>> >>
>> >> At least it would be a design approach I would talk. YMMV
>> >>
>> >> Having said that, I expect someone to say its a bad idea and that they
>> >> have a better solution.
>> >>
>> >> HTH
>> >>
>> >> -Mike
>> >>
>> >> On Jun 27, 2013, at 5:13 PM, Kristoffer Sjögren <[EMAIL PROTECTED]>
>> wrote:
>> >>
>> >>> I see your point. Everything is just bytes.
>> >>>
>> >>> However, the schema is known and every row is formatted according to
>> this
>> >>> schema, although some columns may not exist, that is, no value exist
>> for
>> >>> this property on this row.
>> >>>
>> >>> So if im able to apply these "typed comparators" to the right cell
>> values
>> >>> it may be possible? But I cant find a filter that target specific
>> >> columns?
>> >>>
>> >>> Seems like all filters scan every column/qualifier and there is no way
>> of
>> >>> knowing what column is currently being evaluated?
>> >>>
>> >>>
>> >>> On Thu, Jun 27, 2013 at 11:51 PM, Michael Segel