[jira] [Assigned] (OAK-2720) Misleading traversal warning message while performing query

["Marcel Reutegger (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/OAK-2720?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Marcel Reutegger reassigned OAK-2720:
-------------------------------------

    Assignee: Chetan Mehrotra

[~chetanm], assigning this issue to you because you created the patch and mentioned you want to apply it.

> Misleading traversal warning message while performing query
> -----------------------------------------------------------
>
>                 Key: OAK-2720
>                 URL: https://issues.apache.org/jira/browse/OAK-2720
>             Project: Jackrabbit Oak
>          Issue Type: Bug
>          Components: query
>            Reporter: Chetan Mehrotra
>            Assignee: Chetan Mehrotra
>             Fix For: 1.2
>
>         Attachments: OAK-2720.patch
>
>
> Currently {{ContentMirrorStoreStrategy}} logs a traversal warning if the property index performs node traversal of more than 10000 (default). 
> The intention here being to warn the end user that traversing so many nodes would cause performance issue. Traversal in itself might happen due to many reason like
> # Query not using right index. If the query has two property restriction and one of them is more broad while other is more selective and index is defined only for first then more traversal would be performed. The warning should help the user to create a new index for second property
> # Caller is fetching way more result - Query might end with say 50k result and caller is reading all. Such warning would help user to probably go for pagination
> So above are valid cases. However currently warning is also seen even if end result set is small say 100 but indexed paths are deep. As {{ContentMirrorStoreStrategy}} mirrors the path structure the current counting logic also counts the intermediate traversals. This warning is then misleading as how this internal structure is created is an implementation details of index which end user does not have any control. This leaves following options
> # Use different storage strategy which is more efficient in storage
> # Do not count the intermediate nodes traversed within index path and instead only count the matching node



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