Hi Mike, the issue is that UnifiedHighlighter can rewrite the query using an empty reader even when the index is not empty: https://github.com/apache/lucene/blob/branch_9_0/lucene/highlighter/src/java/org/apache/lucene/search/uhighlight/UnifiedHighlighter.java#L149. Otherwise I agree there would be no problem! It's certainly a bit of an unusual case though.
Julie On Thu, Mar 3, 2022 at 1:10 PM Michael Sokolov <msoko...@gmail.com> wrote: > Isn't this kind of like if a tree falls in the woods and nobody is > there does it make a sound? I mean -- if the index is empty, how can > UH fail? No documents will ever match, ergo no highlights will be > returned, so it seems fine that it is unable to extract terms from the > query. > > On Thu, Mar 3, 2022 at 2:00 PM Julie Tibshirani (Jira) <j...@apache.org> > wrote: > > > > > > [ > https://issues.apache.org/jira/browse/LUCENE-10454?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel > ] > > > > Julie Tibshirani updated LUCENE-10454: > > -------------------------------------- > > Attachment: LUCENE-10454.patch > > > > > UnifiedHighlighter can miss terms because of query rewrites > > > ----------------------------------------------------------- > > > > > > Key: LUCENE-10454 > > > URL: > https://issues.apache.org/jira/browse/LUCENE-10454 > > > Project: Lucene - Core > > > Issue Type: Bug > > > Reporter: Julie Tibshirani > > > Priority: Minor > > > Attachments: LUCENE-10454.patch > > > > > > > > > Before extracting terms from a query, UnifiedHighlighter rewrites the > query using an empty searcher. If the query rewrites to MatchNoDocsQuery > when the reader is empty, then the highlighter will fail to extract terms. > This is more of an issue now that we rewrite BooleanQuery to > MatchNoDocsQuery when any of its required clauses is MatchNoDocsQuery ( > https://issues.apache.org/jira/browse/LUCENE-10412). I attached a patch > showing the problem. > > > This feels like a pretty esoteric issue, but I figured it was worth > raising for awareness. I think it only applies when weightMatches=false, > which isn't the default. I couldn't find any existing queries in Lucene > that would be affected. > > > We ran into it while upgrading Elasticsearch to the latest Lucene > snapshot, since a couple custom queries rewrite to MatchNoDocsQuery when > the reader is empty. > > > > > > > > -- > > This message was sent by Atlassian Jira > > (v8.20.1#820001) > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org > > For additional commands, e-mail: issues-h...@lucene.apache.org > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org > For additional commands, e-mail: dev-h...@lucene.apache.org > >
