PHOENIX-7923 Simplify EXPLAIN value classes

[apurtell]

Simplify EXPLAIN value classes.

Replaces ExplainPlanAttributes' private zero args constructor and package private all args constructor with a private builder. Removes ExplainTable.RegionBoundary in favor of deduping HRegionLocations in getRegionLocationsForExplainPlan via a LinkedHashSet<String>. Replaces ExplainOptions.Builder's regionsSet / verboseSet companion booleans with an inline EnumSet<Option> in the grammar action. The nested Builder type goes away and the parser constructs ExplainOptions directly. No behavior change. EXPLAIN text and JSON output are unchanged.

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

[Copilot]

Pull request overview

This PR simplifies the internal value/option handling for EXPLAIN by removing/flattening builder-style helper types and switching to simpler accumulation/deduping approaches, aiming to keep EXPLAIN text/JSON output unchanged.

Changes:

• Removes ExplainOptions.Builder and updates the SQL parser to accumulate EXPLAIN options directly during parsing.
• Simplifies region-boundary de-duping in ExplainTable#getRegionLocationsForExplainPlan by removing the RegionBoundary helper type.
• Refactors ExplainPlanAttributes construction to use a single private builder-backed constructor.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
phoenix-core-client/src/main/java/org/apache/phoenix/parse/ExplainOptions.java	Removes the public nested builder type used previously to construct ExplainOptions.
phoenix-core-client/src/main/java/org/apache/phoenix/iterate/ExplainTable.java	Replaces RegionBoundary equality/hash logic with string-based boundary keys for deduping region locations.
phoenix-core-client/src/main/java/org/apache/phoenix/compile/ExplainPlanAttributes.java	Replaces the large all-args constructor path with a private builder-backed constructor and updates build().
phoenix-core-client/src/main/antlr3/PhoenixSQL.g	Updates EXPLAIN option parsing to use an EnumSet-tracked accumulator and construct ExplainOptions directly.

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[apurtell]

Test Results

Unit tests (*Test)

Directly impacted EXPLAIN unit tests (3 classes, 123 tests)

Class	Tests	Failures	Errors	Skipped	Notes
ExplainOptionsParserTest	16	0	0	0	Covers every EXPLAIN [(<opt>...)] form including (REGIONS, REGIONS) duplicate-rejection and the legacy WITH REGIONS alias — exercises the new EnumSet<ExplainOpt> seen path.
ExplainJsonOutputTest	2	0	0	0	Covers EXPLAIN (REGIONS, FORMAT JSON) end-to-end JSON output — exercises getDefaultExplainPlan() (now seeded by new ExplainPlanAttributesBuilder().build()) and the regionLocations dedupe path.
ExplainPlanTest	105	0	0	0	The connectionless EXPLAIN-grammar baseline suite. Asserts grammar/JSON shape for every operator class — exercises the new builder-driven private ExplainPlanAttributes ctor on every test.

Other unit tests touching ExplainPlanAttributes / ExplainOptions (9 classes, 315 tests)

Class	Tests	Failures	Errors	Skipped
MergeSortResultIteratorTest	2	0	0	0
ConcatResultIteratorTest	2	0	0	0
JoinQueryCompilerTest	2	0	0	0
StatementHintsCompilationTest	4	0	0	0
QueryPlanTest	4	0	0	0
TenantSpecificViewIndexCompileTest	6	0	0	0
PhoenixSyncTableMapperTest	28	0	0	0
QueryOptimizerTest	52	0	0	1
QueryCompilerTest	215	0	0	2

Integration tests (*IT)

Directly EXPLAIN-impacted ITs (2 classes, 37 tests)

Class	Tests	Failures	Errors	Skipped	Time	Notes
ExplainPlanWithStatsEnabledIT	30	0	0	0	50.8 s	Asserts EXPLAIN text/JSON output across all stats-enabled call sites — primary regression guard for ExplainPlanAttributes + plan-total estimate cells.
QueryLoggerIT	7	0	0	0	47.4 s	Asserts the JDBC query-logger row matches EXPLAIN output, exercising the round-trip through ExplainPlanAttributes.

Wider IT batch 1 — different EXPLAIN call sites (7 classes, 66 tests)

Class	Tests	Failures	Errors	Skipped	Time
ClientHashAggregateIT	2	0	0	0	3.3 s
ProjectArrayElemAfterHashJoinIT	2	0	0	0	2.5 s
DistinctPrefixFilterIT	5	0	0	0	36.8 s
UnionAllIT	19	0	0	0	73.6 s
EmptyColumnIT	7	0	0	0	159.4 s
TenantSpecificViewIndexIT	11	0	0	0	19.0 s
CostBasedDecisionIT	20	0	0	0	160.5 s

Wider IT batch 2 — joins, in-list, delete (4 classes, 370 tests)

Class	Tests	Failures	Errors	Skipped	Time
SortMergeJoinNoIndexIT	35	0	0	0	13.1 s
HashJoinNoIndexIT	33	0	0	0	15.4 s
InListIT	228	0	0	0	145.1 s
DeleteIT	74	0	0	0	205.6 s