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Dawid Weiss commented on LUCENE-5977: ------------------------------------- I looked a bit more closely at the logic of updating offsets in the DefaultIndexingChain and I see offsets *are* propagated for multiple fields, here: {code} // trigger streams to perform end-of-stream operations stream.end(); // TODO: maybe add some safety? then again, its already checked // when we come back around to the field... invertState.position += invertState.posIncrAttribute.getPositionIncrement(); invertState.offset += invertState.offsetAttribute.endOffset(); {code} So the problem with my implementation was that it should have set offsets properly in end(). I still feel this should be verified / asserted cleaner somehow, so I'll leave this issue open looking for suggestions. > IW should safeguard against token streams returning invalid offsets for > multi-valued fields > ------------------------------------------------------------------------------------------- > > Key: LUCENE-5977 > URL: https://issues.apache.org/jira/browse/LUCENE-5977 > Project: Lucene - Core > Issue Type: Improvement > Affects Versions: 4.9, 4.9.1, 4.10, 4.10.1 > Reporter: Dawid Weiss > Priority: Minor > > We have a custom token stream that emits information about offsets of each > token. My (wrong) assumption was that for multi-valued fields a token > stream's offset information is magically shifted, much like this is the case > with positions. It's not the case -- offsets should be increasing and > monotonic across all instances of a field, even if it has custom token > streams. So, something like this: > {code} > doc.add(new Field("field-foo", new CannedTokenStream(token("bar", 1, > 150, 160)), ftype)); > doc.add(new Field("field-foo", new CannedTokenStream(token("bar", 1, > 50, 60)), ftype)); > {code} > where the token function is defined as: > {code} > token(String image, int positionIncrement, int startOffset, int endOffset) > {code} > will result in either a cryptic assertion thrown from IW: > {code} > Exception in thread "main" java.lang.AssertionError > at > org.apache.lucene.index.FreqProxTermsWriterPerField.writeOffsets(FreqProxTermsWriterPerField.java:99) > {code} > or nothing (or a codec error) if run without assertions. > Obviously returning non-shifted offsets from subsequent token streams makes > little sense but I wonder if it could be made more explicit (or asserted) > that offsets need to be increasing between multiple-values. The minimum is to > add some documentation to OffsetAttribute. I don't know if offsets should be > shifted automatically, as it's the case with positions -- this would change > the semantics of existing tokenizers and filters which implement such > shifting internally already. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org