[jira] [Comment Edited] (OAK-6776) Correctly use IndexPlan.supportsPathRestrictions

["Vikas Saurabh (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OAK-6776?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16189490#comment-16189490 ] 

Vikas Saurabh edited comment on OAK-6776 at 10/3/17 10:05 AM:
--------------------------------------------------------------

[~tmueller],
bq. Also, if there is a Lucene index with supportsPathRestrictions, and one without, right now always the one with supportsPathRestrictions is used
Competing plans still fight out the cost war - see {{TraversalAvoidanceTest#competingPlans}} \[0].

I agree that even path restrition support lucene indices have a disadvantage against property indices. That can probably be done here.

Btw, even with that I think "not going for traversal" for some cases (OAK-6734) is correct - yes, it doesn't fix lucene's cost evaluation but we should take deterministic path if traversal can be avoided.

\[0]: https://github.com/apache/jackrabbit-oak/blob/trunk/oak-core/src/test/java/org/apache/jackrabbit/oak/query/TraversalAvoidanceTest.java#L105-L107


was (Author: catholicon):
[~tmueller],
bq. Also, if there is a Lucene index with supportsPathRestrictions, and one without, right now always the one with supportsPathRestrictions is used
Competing plans still fight out the cost war - see {{TraversalAvoidanceTest#competingPlans}} \[0].

I agree that even path restrition support lucene indices have a disadvantage against property indices. That can probably be done here.

Btw, even with that I think "not going for traversal" for some cases (OAK-6734) is correct - yes, it doesn't fix lucene's cost evaluation but we should take deterministic path if traversal can be avoided.

\[0]: https://github.com/apache/jackrabbit-oak/blob/trunk/oak-core/src/test/java/org/apache/jackrabbit/oak/query/TraversalAvoidanceTest.java#L97-L99

> Correctly use IndexPlan.supportsPathRestrictions
> ------------------------------------------------
>
>                 Key: OAK-6776
>                 URL: https://issues.apache.org/jira/browse/OAK-6776
>             Project: Jackrabbit Oak
>          Issue Type: Bug
>          Components: query
>            Reporter: Thomas Mueller
>            Assignee: Thomas Mueller
>             Fix For: 1.8
>
>
> Right now, IndexPlan.supportsPathRestrictions (introduced in OAK-6734) is used in the query engine for some kind of mixed "rule based" and "cost based" [query optimization|https://en.wikipedia.org/wiki/Query_optimization].
> I think the current implementation isn't correct, as (for example) a query with multiple indexes will now use the wrong index in some cases (for example property index, even if the cost of the Lucene index is lower).
> Also, if there is a Lucene index with supportsPathRestrictions, and one without, right now always the one with supportsPathRestrictions is used. This is probably better right now, but once OAK-6735 is resolved, this should be fixed as well.



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