[rules-users] Re: Drools indexing

[Mark Proctor]

Senlin Liang wrote:
> My test query is
>
> result(Index, PaperName, Author, Year, Month) :-
>     paper(Index, name, PaperName),
>     paper(Index, author, Author),
>     paper(Index, year, Year),
>     paper(Index, month, Month).
>
> So drools builds alpha-hashing on the 2nd argument, and name-hashing
> on the 1st argument.
>
> Drools performs much more better than XSB/YAP for this query, and I am
> trying to figure out what is the reason behind.
>   
I don't know the implementation details for XSB or YAP, so not much more 
I can add other than what I've already said. Can't say it simpler than 
we hash literal constraints and index variable constraints.

Mark
> Would you share some ideas?
>
> Thanks,
> Senlin
>
> On Wed, Oct 15, 2008 at 5:40 PM, Mark Proctor <mproctor at codehaus.org> wrote:
>   
>> Senlin Liang wrote:
>>
>> Thanks Mark!
>>
>> I got another question: what kind of indexing is used in drools? what
>> field does it index?
>>
>>
>> It wil index the field used in the constraint
>> Person( name == "mark" )
>> Person( name == $var )
>>
>> Both of those pattners will be indexed no the name field, the first is what
>> we call alpha node hashing, as it's on a literal and the latter is join node
>> index on the name field.
>>
>> I checked the online manual, it seems that I uses hashing index, but i
>> am not sure the details.
>>
>> The reason that I am asking this question is that: drools runs really
>> faster for one of my program. In this program, there is information
>> about DBLP publications:
>>    a(primary key, property, values), where primary key is the primary
>> key of one publication, property can be one of "author, year, ...",
>> and value is the value of the property. I run the query by joining the
>> tables together using the primary key. Drools runs really fast for
>> this program.
>>
>> I am wondering whether there is anything behind to make drools fast.
>> Senlin
>>
>> On Wed, Oct 15, 2008 at 3:41 PM, Mark Proctor <mproctor at codehaus.org> wrote:
>>
>>
>> Senlin Liang wrote:
>>
>> One more question: does drools index intermediate results (such as the
>> inserted objects in actions)?
>>
>>
>> Any inserted object used in == constraints is indexed for that constraint.
>>
>> Is there any cost-based optimization for queries?
>>
>>
>> no
>>
>> Thanks
>>
>> On Wed, Oct 15, 2008 at 9:10 AM, Senlin Liang <senlin.liang at gmail.com>
>> wrote:
>>
>>
>> Hi all,
>>
>> I got one question: How does drools index the objects in memory? Does
>> it use hashing index, based on what? Or drools uses adaptive indexing?
>>
>> Thanks a lot,
>> Senlin
>>
>>
>>
>>
>>
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