The people working on Lucene are pretty smart, and this sort of
query optimization is a well-known trick, so I would not worry
about it.
A dozen years ago at Infoseek, we checked the count of matches
for each term in an AND, and evaluated the smallest one first.
If any of them had zero matches, we didn't evaluate any of them.
I expect that Doug Cutting and the other Lucene folk know those
same tricks.
wunder
On 5/29/08 1:50 PM, "Yongjun Rong" <[EMAIL PROTECTED]> wrote:
> Hi Yonik,
> Thanks for your quick reply. I'm very new to the lucene source code.
> Can you give me a little more detail explaination about this.
> Do you think it will save some memory if docnum = find_match("A") >
> docnum = find_match("B") and put B in the front of the AND query like "B
> AND A AND C"? How about sorting (sort=A,B,C&q=A AND B AND C)? Do you
> think the order of conditions (A,B,C) in a query will affect the
> performance of the query?
> Thank you very much.
> Yongjun
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Yonik
> Seeley
> Sent: Thursday, May 29, 2008 4:12 PM
> To: solr-user@lucene.apache.org
> Subject: Re: Search query optimization
>
> On Thu, May 29, 2008 at 4:05 PM, Yongjun Rong <[EMAIL PROTECTED]>
> wrote:
>> I have a question about how the lucene query parser. For example, I
>> have query "A AND B AND C". Will lucene extract all documents satisfy
>> condition A in memory and then filter it with condition B and C?
>
> No, Lucene will try and optimize this the best it can.
>
> It roughly goes like this..
> docnum = find_match("A")
> docnum = find_first_match_after(docnum, "B") docnum =
> find_first_match_after(docnum,"C")
> etc...
> until the same docnum is returned for "A","B", and "C".
>
> See ConjunctionScorer for the gritty details.
>
> -Yonik
>
>
>
>> or only
>> the documents satisfying "A AND B AND C" will be put into memory? Is
>> there any articles discuss about how to build a optimization query to
>> save memory and improve performance?
>> Thank you very much.
>> Yongjun Rong
>>
