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From Adriano Crestani <adrianocrest...@gmail.com>
Subject Re: basic questions on the new QueryParser
Date Mon, 03 Aug 2009 19:59:54 GMT
I see the "original" package, and the useful OriginalQueryParserHelper
within there, that are meant to ease the transition off of the old
QueryParser to the new one.

First question: is the original package also intended to be Lucene's
"default" QueryParser, going forward?  Ie, most users will simply want
to get Lucene's default QueryParser and parse text into Query objs,
and then expert users will directly use core.* to make their own query
parsers.

If so, maybe we should rename "OriginalQueryParserHelper" to
"DefaultQueryParser" and perhaps move it up into oal.queryParser?

Yes, it's the Lucene's "default" query parser implemented using the new QP
framework.
We already discussed what name should be given to it (original, standard,
default, main, etc) on LUCENE-1567, that
is why we picked the name "original", but there is no specific reason why we
picked it over the others.

Now, about moving it to oal.queryParser, I think it's a subjective decision.
I like it inside oal.queryParser.original, because
we can easily distinguish what is the "original" implementation. But like I
said, it's really subjective.

Second question: say I wanted to start with the DefaultQueryParser,
but tweak how it produces range queries.  EG the old QueryParser
attempted to parse the lower/upper bounds as Date, and then re-encodes
them using DateTools (LUCENE-1768 is already open to do this plus
NumericQuery "for real"... I'm just using it as a use case of how an
outside consumer of this API could tweak the default QueryParser).

If I want to do this using the new QueryParser, could I:

 * First get the DefaultQueryParser

 * Call getQueryBuilder to get its QueryBuilder

 * Call QueryBuilder.setBuilder(RangeQueryNode.class, new
   MyRangeQueryNodeBuilder()), where MyRangeQueryNodeBuilder is my
   new class that handles the dates.

?

Ie, is that (swapping in your own QueryBuilder) the right way to tweak
how the DefaultQueryParser would create queries?

If you want to be able to create NumericQuery objects based on the field
data type (float, int, date, etc), which the user specified in some kind of
configuration, changing the builders would not be enough, for these 2
reasons:

1- Builders are meant to be used only to build the final objects from query
nodes, processing, like converting the range values to the correct data
format should be ideally be performed in a processor.

2- Builders have no access to configuration at build time, the only query
parser phase able to do that is the query processing phase.

So, you will need to:

- create an Attribute to hold the data type for each range field, so you can
set the data type on this attribute and add it to the QueryConfigHandler
(you may call originalQP.getQueryConfigHandler() to get it)

- create a processor that reads this configuration from the
QueryConfigHandler and for each RangeQueryNode object and convert their
values to the correct format

- add the processor to the current OriginalQueryParserPipeline (calling
defaultQP.getQueryNodeProcessor().addProcessor(new
MyNewRangeQueryNodeProcessor())

- create a builder that creates NumericQuery objects from RangeQueryNode and
add it to the builders' map:
defaultQP.getQueryBuilder().setBuilder(RangeQueryNode.class, new
MyRangeQueryNodeBuilder())

I think this is what should be done on LUCENE-1768. But, if you decide you
don't need to convert the range values based on the field data type
specified by the user and you want to hardcode that on the builder, you can
do the way you described. However, ideally, if you do any query processing,
like values conversion, you should create a processor for that, because they
were desinged for that.

Best Regards,
Adriano Crestani Campos


On Mon, Aug 3, 2009 at 11:12 AM, Michael McCandless <
lucene@mikemccandless.com> wrote:

> Second question: say I wanted to start with the DefaultQueryParser,
> but tweak how it produces range queries.  EG the old QueryParser
> attempted to parse the lower/upper bounds as Date, and then re-encodes
> them using DateTools (LUCENE-1768 is already open to do this plus
> NumericQuery "for real"... I'm just using it as a use case of how an
> outside consumer of this API could tweak the default QueryParser).
>
> If I want to do this using the new QueryParser, could I:
>
>  * First get the DefaultQueryParser
>
>  * Call getQueryBuilder to get its QueryBuilder
>
>  * Call QueryBuilder.setBuilder(RangeQueryNode.class, new
>    MyRangeQueryNodeBuilder()), where MyRangeQueryNodeBuilder is my
>    new class that handles the dates.
>
> ?
>
> Ie, is that (swapping in your own QueryBuilder) the right way to tweak
> how the DefaultQueryParser would create queries?
>

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