Some comments on JIRA suggest that this is expected, because natural merges can have a variety of triggers while forced merges are always called by the app. I guess you could argue that MERGE_FINISHED is a different trigger, but are there use-cases for doing things differently in findForcedMerges depending on the merge trigger?
https://issues.apache.org/jira/browse/LUCENE-4472?focusedCommentId=13476920&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-13476920 . On Mon, Jun 20, 2022 at 3:26 PM Bruno Roustant <bruno.roust...@gmail.com> wrote: > I agree this AlwaysForceMergePolicy is not working correctly. It's just a > test I did to easily understand how MergeTrigger.MERGE_FINISHED was working. > > Anyway my question is only about the MergeTrigger not present in the call > to findForcedMerges(), to know if it is expected or inconsistent with the > other find merges methods. > > > Le lun. 20 juin 2022 à 14:26, Adrien Grand <jpou...@gmail.com> a écrit : > >> Wouldn't this be a bug in the AlwaysForceMergePolicy, which should return >> no merges if there is already a single segment with no deletes? >> >> On Mon, Jun 20, 2022 at 1:30 PM Bruno Roustant <bruno.roust...@gmail.com> >> wrote: >> >>> If I use a simple "AlwaysForceMergePolicy" in a test, I can see that >>> when a run IndexWriter.forceMerge(), the first call to >>> AlwaysForceMergePolicy.findForcedMerges() is done for the >>> MergeTrigger.EXPLICIT. But then, at IndexWriter.merge() line 4531, >>> MergePolicy.findForcedMerges() is called with MergeTrigger.MERGE_FINISHED >>> to merge the segments produced by the output of the first explicit forced >>> merge, and so on. For this degenerated AlwaysForceMergePolicy, the test >>> runs merges in an infinite loop. >>> >>> Le lun. 20 juin 2022 à 11:11, Adrien Grand <jpou...@gmail.com> a écrit : >>> >>>> You seem to imply that `forceMerge` runs a cascaded merge where the >>>> first merge creates some new segments that become inputs to a second merge. >>>> Have you considered running a single merge? We had a discussion about >>>> cascaded forced merges and TieredMergePolicy last year and ended up >>>> changing `findForcedMerges` to never run cascaded merges: >>>> https://issues.apache.org/jira/browse/LUCENE-7020. >>>> >>>> On Mon, Jun 20, 2022 at 10:31 AM Bruno Roustant < >>>> bruno.roust...@gmail.com> wrote: >>>> >>>>> MergePolicy "find merges" methods take a MergeTrigger as parameter, >>>>> except findForcedMerges() and findForcedDeletesMerges(). >>>>> In my use-case, I could leverage a MergeTrigger in findForcedMerges(), >>>>> which can be EXPLICIT or MERGE_FINISHED, to differentiate the merge >>>>> selection between the initial explicit call and the subsequent calls >>>>> triggered after the first merges. >>>>> >>>>> Should we add a MergeTrigger parameter to all MergePolicy "find >>>>> merges" methods for consistency? >>>>> If so, is it an internal or public API? (should this change stay in >>>>> the main branch only) >>>>> >>>> >>>> >>>> -- >>>> Adrien >>>> >>> >> >> -- >> Adrien >> > -- Adrien
