[jira] [Resolved] (OAK-9522) Index cost estimation: prefer union query with path restriction

["Thomas Mueller (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/OAK-9522?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Thomas Mueller resolved OAK-9522.
---------------------------------
    Resolution: Fixed

> Index cost estimation: prefer union query with path restriction
> ---------------------------------------------------------------
>
>                 Key: OAK-9522
>                 URL: https://issues.apache.org/jira/browse/OAK-9522
>             Project: Jackrabbit Oak
>          Issue Type: Improvement
>            Reporter: Thomas Mueller
>            Assignee: Thomas Mueller
>            Priority: Major
>              Labels: index, lucene, query
>             Fix For: 1.42.0, 1.22.9
>
>
> If there is a query of this form with an index that supports path restrictions (evaluatePathRestrictions = true):
> {noformat}
> select * from [nt:base] where [indexedProperty] = x 
> and (issamenode('/content') or isdescendantnode('/content'))
> {noformat}
> then the path restriction isn't used in the index.
> This is unfortunate, because the index returns a lot more results, and the query engine will have to check if the path matches the condition.
> How this works: the query engine creates two possible queries:
> * plan a: one with just the [indexedProperty] = x condition, and no path restriction
> * plan b: a union query, where one side uses issamenode and the other side uses isdescendantnode.
> The index will return the same cost no matter if a path condition is there or not. And that's why the query engine will pick plan a: because the cost of the union query is higher.
> The index should return a lower cost if there is a path restriction. (Right now the query engine will reduce the cost if there is a path restriction, but that's not sufficient for this case).



--
This message was sent by Atlassian Jira
(v8.3.4#803005)