PHOENIX-7882 Per scan EXPLAIN output improvements

[apurtell]

Per-scan INDEX <name> [<kind>], SALT BUCKETS <n>, REGIONS PLANNED <n>.

ExplainTable.explain(...) emits INDEX before ROW TIMESTAMP FILTER (name from tableRef.getTable().getName(). Local indexes print just <idx>), with a <kind> token (LOCAL / GLOBAL / UNCOVERED GLOBAL) when the target is an INDEX, SALT BUCKETS when getBucketNum() is set, and REGIONS PLANNED from the split count.

Adds getSplitCount() to BaseResultIterators and indexName, indexKind, saltBuckets, regionsPlanned to ExplainPlanAttributes.

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

[Copilot]

Pull request overview

This PR enhances Phoenix per-scan EXPLAIN output by adding consistent, structured scan metadata (index name/kind, salt buckets, and planned region/split count) to both the rendered plan text and the structured ExplainPlanAttributes, along with corresponding test and normalizer updates.

Changes:

• Emit per-scan INDEX <name> [<kind>], SALT BUCKETS <n>, and REGIONS PLANNED <n> lines in ExplainTable.explain(...), and plumb split count via BaseResultIterators.getSplitCount().
• Extend ExplainPlanAttributes (and builder) with indexName, indexKind, saltBuckets, and regionsPlanned.
• Update unit/integration tests and explain normalizers to account for the new output (including normalizing variable region counts).

Reviewed changes

Copilot reviewed 14 out of 14 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/iterate/ExplainTable.java	Adds per-scan INDEX/SALT BUCKETS/REGIONS PLANNED emission and populates new explain attributes.
phoenix-core-client/src/main/java/org/apache/phoenix/iterate/BaseResultIterators.java	Supplies split count for the new REGIONS PLANNED line via getSplitCount().
phoenix-core-client/src/main/java/org/apache/phoenix/compile/ExplainPlanAttributes.java	Adds new structured fields + builder wiring and JSON property ordering.
phoenix-core/src/test/java/org/apache/phoenix/query/explain/ExplainPlanTest.java	Updates expected explain text and JSON shapes; adds coverage for index kind tokens.
phoenix-core/src/test/java/org/apache/phoenix/query/explain/ExplainPlanTestUtil.java	Extends fluent assertions for the newly added structured explain attributes.
phoenix-core/src/test/java/org/apache/phoenix/query/explain/ExplainTextNormalizer.java	Normalizes the variable REGIONS PLANNED <n> count for stable comparisons.
phoenix-core/src/test/java/org/apache/phoenix/query/explain/ExplainJsonNormalizer.java	Nulls regionsPlanned during normalization to avoid environment-dependent diffs.
phoenix-core/src/it/java/org/apache/phoenix/end2end/SortMergeJoinMoreIT.java	Formatting-only adjustments to keep tests aligned with updated output/style.
phoenix-core/src/it/java/org/apache/phoenix/end2end/join/SortMergeJoinLocalIndexIT.java	Formatting-only adjustments.
phoenix-core/src/it/java/org/apache/phoenix/end2end/join/SortMergeJoinGlobalIndexIT.java	Formatting-only adjustments.
phoenix-core/src/it/java/org/apache/phoenix/end2end/Bson3IT.java	Formatting-only adjustments.
phoenix-core/src/it/java/org/apache/phoenix/end2end/Bson4IT.java	Formatting-only adjustments.
phoenix-core/src/it/java/org/apache/phoenix/end2end/Bson5IT.java	Formatting-only adjustments.
phoenix-core-client/src/main/java/org/apache/phoenix/expression/util/bson/UpdateExpressionUtils.java	Wraps a long log statement line for style/line-length compliance.

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[apurtell]

Test Results

Unit tests (surefire)

Test	Result
ExplainPlanTest	62 run, 0 failures
QueryPlanTest	4 run, 0 failures
QueryCompilerTest	215 run, 0 failures (2 skipped)
QueryOptimizerTest	49 run, 0 failures (1 skipped)

Integration tests (failsafe, forks=2)

Test	Result
Bson4IT	32 run, 0 failures (6 skipped)
Bson5IT	2 run, 0 failures
SortMergeJoinMoreIT	10 run, 0 failures
SortMergeJoinGlobalIndexIT	35 run, 0 failures
SortMergeJoinLocalIndexIT	35 run, 0 failures
ExplainPlanWithStatsEnabledIT	28 run, 0 failures
ExplainPlanWithStatsDisabledIT	17 run, 0 failures

The IT selection covers the five test files modified on the branch plus the two explain-focused ITs that exercise the changed client code.