PHOENIX-7935 Propagate requested EXPLAIN options to nested plan contexts

[apurtell]

Previously PhoenixStatement set ExplainOptions only on the root plan's StatementContext. Nested plans (hash-join / semi-join / anti-join build sides, UNION ALL branches, sort-merge-join halves, and ClientScanPlan / ClientAggregatePlan / TupleProjectionPlan wrappers) kept their default options and rendered as plain explain output. Each parent's getExplainPlan() now copies getContext().getExplainOptions() onto its child plans' contexts before composing them. ExplainTable no longer special-cases the root scan.

Co-authored-by: Claude Opus 4.8[1m] noreply@anthropic.com

[Copilot]

Pull request overview

This PR ensures EXPLAIN option selections (e.g., VERBOSE, REGIONS, FORMAT JSON) are consistently applied throughout nested query plan structures, so child scans/subplans render with the same disclosure level as the root plan.

Changes:

• Propagates the parent plan’s ExplainOptions into nested/child StatementContexts before composing ExplainPlans.
• Updates join/union plan explain composition to ensure both halves/branches/subplans render in the requested explain mode.
• Ensures client wrapper plans pass explain options through to their delegate plans (and associated contexts used for client-side filters).

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
phoenix-core-client/src/main/java/org/apache/phoenix/execute/UnionPlan.java	Copies root ExplainOptions to each UNION branch context before composing branch explain plans.
phoenix-core-client/src/main/java/org/apache/phoenix/execute/TupleProjectionPlan.java	Copies delegate ExplainOptions onto the separate post-filter statementContext so verbose client filters render consistently.
phoenix-core-client/src/main/java/org/apache/phoenix/execute/SortMergeJoinPlan.java	Propagates ExplainOptions to both LHS/RHS plan contexts prior to building the combined explain plan.
phoenix-core-client/src/main/java/org/apache/phoenix/execute/HashJoinPlan.java	Propagates ExplainOptions to each hash-join subplan’s inner plan context before rendering subplan explain steps/attributes.
phoenix-core-client/src/main/java/org/apache/phoenix/execute/ClientScanPlan.java	Pushes wrapper context ExplainOptions down into the delegate plan context before delegating explain.
phoenix-core-client/src/main/java/org/apache/phoenix/execute/ClientAggregatePlan.java	Pushes wrapper context ExplainOptions down into the delegate plan context before delegating explain.

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