[Xapian-discuss] query within value range

Mark Clarkson mark.clarkson at smorg.co.uk
Tue Jun 5 16:23:56 BST 2007

On Tue, 2007-06-05 at 15:21 +0100, Richard Boulton wrote:
> 1) index your data storing the value you wish to sort by in a value (ie, 
> not as a term).  Sorting is only possible in string order, so if you 
> want to store a number to sort by, this needs to be marshalled into a 
> form in which numerical sort order is the same as string sort order: for 
> integers in a known range (eg, dates), the easiest way to do this is to 
> pad with leading zeros so that all the values are the same length.
> 2) assuming you're using the query parser, add a value-range processor 
> to the parser using "add_valuerangeprocessor()".  Supposing you're using 
> a DateValueRangeProcessor, you'd might do something like:
>   qp.add_valuerangeprocessor(Xapian::DateValueRangeProcessor(1))
> Then, a query like "20060501..20070503" will become a ValueRange query, 
> returning only those documents for which the value in slot 1 is in the 
> range 20060501 to 20070503.
> Note that value range processors don't use prefixes, so you don't need 
> to specify "date:" in the query - the ".." is picked up as indicating a 
> range.
> 3) If you're not using the query parser, you can build the value range 
> query directly, using the OP_VALUE_RANGE operator (and an associated 
> constructor).

Your excellent clear description is just what I needed. Thanks very
much. Would I be right in saying that there can be only one value range
item that can be used per query when using the query parser?


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