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https://issues.apache.org/jira/browse/OAK-4934?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15571668#comment-15571668
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Chetan Mehrotra commented on OAK-4934:
--------------------------------------

[~tmueller] Thoughts?

> Query shapes for JCR Query
> --------------------------
>
>                 Key: OAK-4934
>                 URL: https://issues.apache.org/jira/browse/OAK-4934
>             Project: Jackrabbit Oak
>          Issue Type: Wish
>          Components: query
>            Reporter: Chetan Mehrotra
>
> For certain requirements it would be good to have a notion/support to deduce 
> query shape [1]
> {quote}
>  A combination of query predicate, sort, and projection specifications.
>  For the query predicate, only the structure of the predicate, including the 
> field names, are significant; the values in the query predicate are 
> insignificant. As such, a query predicate { type: 'food' } is equivalent to 
> the query predicate { type: 'utensil' } for a query shape.
> {quote}
> So transforming that to Oak the shape should represent a JCR-SQL2 query 
> string which is a canonical representation of actual query ignoring the 
> property restriction values. 
> Example we have 2 queries
> * SELECT   * FROM [app:Asset] AS a WHERE  a.[jcr:content/metadata/status] = 
> 'published'
> * SELECT   * FROM [app:Asset] AS a WHERE  a.[jcr:content/metadata/status] = 
> 'disabled'
> The query shape would be 
> SELECT * FROM [app:Asset] AS a WHERE  a.[jcr:content/metadata/status] = 'A'. 
> The plan for query having given shape would remain same irrespective of value 
> of property restrictions
> The shape can then be used for
> * Stats Collection - Currently stats collection gets overflown if same query 
> with different value gets invoked
> * Allow configuring hints - See support in Mongo [2] for an example. One 
> specify via config that for a query of such and such shape this index should 
> be used
> * Less noisy diagnostics - If a query gets invoked with bad plan the QE can 
> log the warning once instead of logging it for each query invocation 
> involving different values.
> [1] https://docs.mongodb.com/manual/reference/glossary/#term-query-shape
> [2] https://docs.mongodb.com/manual/reference/command/planCacheSetFilter/



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