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https://issues.apache.org/jira/browse/PHOENIX-7876?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrew Kyle Purtell reassigned PHOENIX-7876:
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Assignee: Andrew Kyle Purtell
> Improve EXPLAIN
> ---------------
>
> Key: PHOENIX-7876
> URL: https://issues.apache.org/jira/browse/PHOENIX-7876
> Project: Phoenix
> Issue Type: Improvement
> Reporter: Andrew Kyle Purtell
> Assignee: Andrew Kyle Purtell
> Priority: Major
>
> Phoenix's {{EXPLAIN [WITH REGIONS]}} output is today incomplete and easy to
> misread for both query analysis and performance investigation.
> DDL EXPLAINs don't show columns/PK/families/salt/splits. Non-trivial joins
> render with almost no detail. The cost vector advertises three dimensions but
> only compares IO, and estimates/statistics are unreliable. Some optimizations
> are incorrectly categorized, for example some shown as row-eliminating
> predicates are actually column-projection optimizations. The operator trees
> of complex queries are flattened to a single ident level. Many planner facts
> are not surfaced at all, such as which rule chooses an index, which indexes
> the optimizer considered but rejected, what query rewrites took place (e.g.
> subquery decorrelation, star-join detection, right-to-left normalization,
> HAVING lift, RVC-offset translation, reverse-scan substitution, UNION ORDER
> BY, index expression substitution, and more), the specific hash-join strategy
> chosen, salt bucket counts, local vs. global vs. uncovered-global index
> distinctions, the particular flavor of atomic upsert chosen and server-side
> atomic update expressions, multi tenant context, CDC scope, transaction
> provider, projection lists, predicate to filter attribution, hints honored vs
> ignored, and the structure of the JSON/BSON/array path expressions evaluated
> server-side.
> This proposal closes all of those gaps. Details provided in the design
> document.
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