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https://issues.apache.org/jira/browse/OAK-4934?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Davide Giannella updated OAK-4934:
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Fix Version/s: (was: 1.14.0)
> 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
> Priority: Major
> Fix For: 1.16.0
>
>
> 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 (xpath query gets transformed to SQL2) 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. Path restriction can cause some difference though
> 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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