[jira] (PHOENIX-7876) Improve EXPLAIN

["Andrew Kyle Purtell (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PHOENIX-7876 ]


    Andrew Kyle Purtell deleted comment on PHOENIX-7876:
    ----------------------------------------------

was (Author: apurtell):
Attached as  [^PHOENIX_7876_MERGE_TEST_REPORT.md] is a report on the status of a complete sweep of the unit test suite. In short all tests are passing except for five pre-existing or environmental failures that have been root caused to be provably not related to the changes in the dev branch. 

> 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
>             Fix For: PHOENIX-7876-feature
>
>         Attachments: PHOENIX_EXPLAIN_EXAMPLES.md, PHOENIX_EXPLAIN_REVIEWER_GUIDE.md
>
>
> 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. 
> Design document: https://docs.google.com/document/d/10H_MNWGQL7ZzsPmIVBMz7T1jJroez8AYpvwouKcBVQo/edit?tab=t.0



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