DocValuesIterator: advance vs advanceExact

[Alexander Buloichik <Al...@epam.com.INVALID>]

Hi.

I'm trying to retrieve field values in my own LeafCollector (Lucene 8.11.1). But I didn't find good tutorial how to do it.
So, I get SortedSetDoc from LeafReader, then Lucene calls my implementation of LeafCollector.collect() method, and I try to get values from SortedSetDoc inside my implementation of LeafCollector.collect() method.

What should I call for move SortedSetDoc's pointer to the required document('doc' parameter of LeafCollector.collect(int doc)) ? advance(doc) or advanceExact(doc) ?

I'm using SortedSetDoc.advanceExact() and it works good.

But when I'm trying to call BinaryDocValues.advanceExact() for other field, it always returns true (see Lucene80DocValuesProducer.java:685), even in case doc >= maxDoc.
If I'm using advance(doc) and checking that "advance(doc)==doc" (against case of "document number is greater to target") - it works good.

But SortedSetDoc.advance(doc) always returns 'doc+1', not a 'doc' (IndexedDISI.java:385).

--
Alexander Buloichik

Re: DocValuesIterator: advance vs advanceExact

[Adrien Grand <jp...@gmail.com>]

Hi Alexander,

In general, advance(target) is best used to implement queries and
advanceExact(target) for collectors.

See javadocs for advanceExact(target), this method may only be called
on doc IDs that are between 0 included and maxDoc excluded.

On Thu, Feb 3, 2022 at 10:00 AM Alexander Buloichik
<Al...@epam.com.invalid> wrote:
>
> Hi.
>
> I'm trying to retrieve field values in my own LeafCollector (Lucene 8.11.1). But I didn't find good tutorial how to do it.
> So, I get SortedSetDoc from LeafReader, then Lucene calls my implementation of LeafCollector.collect() method, and I try to get values from SortedSetDoc inside my implementation of LeafCollector.collect() method.
>
> What should I call for move SortedSetDoc's pointer to the required document('doc' parameter of LeafCollector.collect(int doc)) ? advance(doc) or advanceExact(doc) ?
>
> I'm using SortedSetDoc.advanceExact() and it works good.
>
> But when I'm trying to call BinaryDocValues.advanceExact() for other field, it always returns true (see Lucene80DocValuesProducer.java:685), even in case doc >= maxDoc.
> If I'm using advance(doc) and checking that "advance(doc)==doc" (against case of "document number is greater to target") - it works good.
>
> But SortedSetDoc.advance(doc) always returns 'doc+1', not a 'doc' (IndexedDISI.java:385).
>
> --
> Alexander Buloichik
>


-- 
Adrien

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