ToParentBlockJoinCollector provides no way to access computed scores and the maxScore [LUCENE-4077]

[asfimport]

The constructor of ToParentBlockJoinCollector allows to turn on the tracking of parent scores and the maximum parent score, however there is no way to access those scores because:

• maxScore is a private field, and there is no getter
• TopGroups / GroupDocs does not provide access to the scores for the parent documents, only the children

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Migrated from LUCENE-4077 by Christoph Kaser, resolved May 31 2012 Attachments: LUCENE-4077.patch (versions: 4)

[asfimport]

Michael McCandless (@mikemccand) (migrated from JIRA)

Patch.

I added getMaxScore to ToParentBlockJoinCollector, and GroupDocs.score to access the aggregated score for the group. I also added a ScoreMergeMode enum to TopGroups.merge to control how the scores from the same group across multiple shards should be merged.

[asfimport]

Christoph Kaser (migrated from JIRA)

Hello Mike,

thank you for the patch. There is one small problem: ToParentBlockJoinCollector.getMaxScore() always returns NaN. This happens because maxScore is initialized as

private float maxScore = Float.NaN;

and then updated as

maxScore = Math.max(score, maxScore);

which is always NaN.

I hope I applied the patch to the correct revision and this is not caused by a version conflict.

[asfimport]

Michael McCandless (@mikemccand) (migrated from JIRA)

Ugh, sorry. Sneaky NaN!

I added an assert in TestBJQ that shows the failure, then fixed it...

[asfimport]

Christoph Kaser (migrated from JIRA)

This patch works perfectly for my application. Thank you!

[asfimport]

Michael McCandless (@mikemccand) (migrated from JIRA)

Super, thanks for testing Christoph. I'll commit shortly...

[asfimport]

Michael McCandless (@mikemccand) (migrated from JIRA)

I decided to add the maxScore to TopGroups so it's consistent w/ TopDocs; this way you don't have to ask the collector for the maxScore....

[asfimport]

Christoph Kaser (migrated from JIRA)

Hi Mike,

shouldn't TopGroups.maxScore contain the maximum parent score? If I am not mistaken, the way it is built now, it contains the maximum child score over all children.

This is due to this line in ToParentBlockJoinCollector.getTopGroups():

maxScore = Math.max(maxScore, topDocs.getMaxScore());

I think it should read:

totalMaxScore = Math.max(totalMaxScore, og.score);

Otherwise, topGroups.maxScore is different to ToParentBlockJoinCollector.getMaxScore()

[asfimport]

Michael McCandless (@mikemccand) (migrated from JIRA)

Otherwise, topGroups.maxScore is different to ToParentBlockJoinCollector.getMaxScore()

Woops, you're right, thanks. In fact I should be passing the maxScore that the collector already computed, not recomputing it in ToParentBJC.getTopGroups...

[asfimport]

Michael McCandless (@mikemccand) (migrated from JIRA)

New patch, using the collector's maxScore in TPBJC.getTopGroups.

[asfimport]

Christoph Kaser (migrated from JIRA)

Thank you, now it works perfectly!

[asfimport]

Michael McCandless (@mikemccand) (migrated from JIRA)

Super, thanks Christoph, I'll commit shortly...