Hi all!
Just before diving in the core Lucene code, I would like to ask once again if
there are detailed tutorials on SpanQuery execution algorithm, with postings
retrieval and positional data matching.
Best Regards,
Igor
03.06.13, 21:15, "Igor Shalyminov" <ishalymi...@yandex-team.ru>":
>
> Hello!
>
> I've implemented a SpanQuery class that acts like SpanPositionCheckQuery but
> also matches payloads.
> For example, here is the "gram" field in a single indexed document:
>
> "gram": N|1|1 sg|1|0 A|2|0 pl|2|0 A|3|0 sg|3|0
>
> Every token's meaning is as follows:
> N - grammatical annotation | 1 - parse number (payload) | 1 - position
> increment
>
> So, the document has a single word position which has 3 ambiguous parses, #1
> and #2, and #3. Each parse has 2 annotations, "N, sg", "A, pl", and "A, sg".
> And my SpanQuery is supposed not to match annotations from different parses,
> e.g. "sg & pl" should not be matched, but "N & sg" should be.
>
> The logic is:
>
> @Override
> protected AcceptStatus acceptPosition(Spans spans) throws IOException {
> boolean result = spans.isPayloadAvailable();
> if (result == true) {
> Collection<byte[]> payloads = spans.getPayload();
> int first_payload = PayloadHelper.decodeInt(payloads.iterator().next(),
> 0);
> for (byte[] payload: payloads) {
> int decoded_payload = PayloadHelper.decodeInt(payload, 0);
> if(decoded_payload != first_payload) {
> return AcceptStatus.NO;
> }
> }
> }
> return AcceptStatus.YES;
> }
>
> Then, for the query "sg & pl", which is a wrapped unordered SpanNearQuery:
> ParseMatchingSpanQuery(SpanNearQuery("gram:sg", "gram:pl", false, -1)) -
> acceptPosition is called the first time with payloads array containing ['1',
> '2'], and second time - with just a ['3']. The second match actually matches,
> and it's totally unintuitive to me.
> To my understanding, it should be called with pairs of spans, ideally ['1',
> '2'], ['1', '3']. Why does it not?:)
> Could you please explain to me the logic of matching with payload checking?
>
> --
> Best Begards,
> Igor
>
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