lucene-solr-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Fergus McMenemie <>
Subject Re: fq vs. q
Date Wed, 10 Jun 2009 07:30:06 GMT
>On Tue, Jun 9, 2009 at 7:25 PM, Michael Ludwig <> wrote:

>> A filter query is cached, which means that it is the more useful the
>> more often it is repeated. We know how often certain queries arise, or
>> at least have the means to collect that data - so we know what might be
>> candidates for filtering.
Sorry but I cant make any sense of the above. Could you have another go 
at explaining it?

>> The result of a filter query is cached and then used to filter a primary
>> query result using set intersection. If my filter query result comprises
>> more than 50 % of the entire document collection, its selectivity is
>> poor. I might need it despite this fact, but it might also be worth
>> while thinking about how to reframe the requirement, allowing for more
>> efficient filters.

So, just to be explicit, if I have a query containing:

   &fq=EventType:fair&fq=EventType:film&fq=LAT:[50 TO 60]&fq=LONG:[-1 TO 1]

The first time this is encountered it is going to cause four queries
of the entire index and cause four sets of document ID's to be cached.
Subsequent queries will reuse the various cached entries as appropriate.
Is that correct?

I guess in the above case where my GEO search window will keep changing
I should ideally arrange that the lat and long element is added to the q 
parameter to stop my cache being cluttered.

Also what happens when the filter is full? If there any accounting of 
which cache entries are getting the most or most recent hits?

Regards Fergus

View raw message