fix: [bug] narrow BIGINT to INTEGER for int-domain function arguments (#5660)

[AjimelecGonzalez]

Description

PPL queries that pass integer arithmetic as an argument to functions requiring Java int parameters fail when Calcite is enabled:

    mvindex(arr, 1 + 1)      -> CompileException: arrayItemOptional(List, long, ...)
	left('abcdef', 1 + 1)    -> Unable to implement: SqlFunctions.left(String, long)
	round(123.456, 1 + 0)    -> SqlFunctions.sround(BigDecimal, long)

Root cause: PPL widens INTEGER arithmetic to BIGINT for overflow safety (#5603), so expressions like 1 + 1 produce BIGINT. Many Calcite runtime methods (ITEM, LEFT, RIGHT, ROUND, TRUNCATE, SUBSTRING, CONV, SHA2, etc.) take Java int parameters. Since SqlTypeFamily.INTEGER contains BIGINT, the call passes type checking but fails at code generation because the JVM cannot auto-narrow long to int.

The bug surfaces on:
- Local execution: Calcite EnumerableCalc codegen -> Unable to implement

Fix:
- PPLFuncImpTable.resolve: for functions whose implementations require int, narrow BIGINT arguments back to INTEGER at the plan layer.

Overflow safety is preserved: the arithmetic itself still computes in BIGINT; only the final value handed to an int-domain parameter is narrowed. Arithmetic operators, comparisons, cast(x as long), aggregations, and long-field arithmetic are left untouched.

Also fixes the pre-existing case where an explicit cast(x as long) is passed to these functions.

Testing:

• Unit tests in RelJsonSerializerTest covering the serialization-layer type preservation.
• Integration tests in CalciteArrayFunctionIT, CalciteTextFunctionIT, and CalciteMathematicalFunctionIT covering mvindex, left, right, substring, round, truncate, conv, and sha2 with
  arithmetic and cast(x as long) arguments.
• Regression tests confirming arithmetic with doc-value fields, aggregations, cast(x as long), and long-field arithmetic still return the correct BIGINT types.

Related Issues

Resolves #5660

Related to #5603 (introduced the integer arithmetic widening that exposed this)

Check List

• New functionality includes testing.
• New functionality has been documented.
• New functionality has javadoc added.
• New functionality has a user manual doc added.
• New PPL command checklist all confirmed.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff or -s.
• Public documentation issue/PR created.

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PR Code Suggestions ✨

Latest suggestions up to 0d3b11a
Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Add signature parameter bounds validation Add bounds checking before accessing signature parameter types to prevent potential IndexOutOfBoundsException. The method narrows arguments based on positions in INT_PARAM_POSITIONS but doesn't verify these positions are valid for the matched signature's parameter list. core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java [765-775] for (int pos : intPositions) { - if (pos < args.length && args[pos].getType().getSqlTypeName() == SqlTypeName.BIGINT) { + if (pos < args.length && pos < signature.getParamTypes().size() + && args[pos].getType().getSqlTypeName() == SqlTypeName.BIGINT) { if (narrowed == null) { narrowed = args.clone(); } RelDataType intType = TYPE_FACTORY.createTypeWithNullability( TYPE_FACTORY.createSqlType(SqlTypeName.INTEGER), args[pos].getType().isNullable()); narrowed[pos] = builder.makeCast(intType, args[pos]); } } Suggestion importance[1-10]: 7 __ Why: The suggestion correctly identifies a potential IndexOutOfBoundsException risk when accessing signature.getParamTypes(). Adding bounds checking (pos < signature.getParamTypes().size()) would prevent runtime errors if INT_PARAM_POSITIONS contains positions beyond the signature's parameter list.	Medium
General	Verify signature expects INTEGER type Validate that the signature's parameter at pos actually expects INTEGER type before narrowing. The current logic assumes all positions in INT_PARAM_POSITIONS always need narrowing, but doesn't verify the signature's expected type matches this assumption. core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java [754-766] private static RexNode[] narrowBigintArgs( RexBuilder builder, BuiltinFunctionName functionName, CalciteFuncSignature signature, RexNode... args) { // Only narrow the int-domain control positions of functions known to require Java int params. int[] intPositions = INT_PARAM_POSITIONS.get(functionName); if (intPositions == null) { return args; } RexNode[] narrowed = null; for (int pos : intPositions) { - if (pos < args.length && args[pos].getType().getSqlTypeName() == SqlTypeName.BIGINT) { + if (pos < args.length && pos < signature.getParamTypes().size() + && args[pos].getType().getSqlTypeName() == SqlTypeName.BIGINT + && signature.getParamTypes().get(pos).getSqlTypeName() == SqlTypeName.INTEGER) { Suggestion importance[1-10]: 6 __ Why: The suggestion adds validation to ensure the signature's parameter type at pos is actually INTEGER before narrowing. This makes the logic more defensive and explicit, though the current implementation relies on INT_PARAM_POSITIONS being correctly maintained to match signature expectations.	Low

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Previous suggestions

Suggestions up to commit c1295f6

Category	Suggestion	Impact
Possible issue	Add bounds check for parameter position The loop checks if any argument needs casting but doesn't validate that parameterTypes has enough positions for all arguments. If args.length exceeds the size of any parameter type combination, accessing position i in expectsIntegerAtPosition could cause index issues. Add a bounds check before calling expectsIntegerAtPosition. core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java [771-777] for (int i = 0; i < args.length; i++) { if (args[i].getType().getSqlTypeName() == SqlTypeName.BIGINT + && i < parameterTypes.stream().mapToInt(List::size).min().orElse(0) && expectsIntegerAtPosition(parameterTypes, i)) { needsCast = true; break; } } Suggestion importance[1-10]: 3 __ Why: The suggestion identifies a potential bounds issue, but expectsIntegerAtPosition already handles bounds checking by returning false when position >= combination.size() (line 850-852). The proposed fix adds unnecessary complexity with a stream operation that doesn't improve safety.	Low
General	Verify original types before narrowing The narrowing logic is applied to all non-arithmetic/non-comparison calls, but the method narrowOperandsToOriginalType unconditionally narrows all BIGINT operands to INTEGER. This could break functions that legitimately accept BIGINT parameters. Consider checking if the original call operand types were narrower before applying the cast. opensearch/src/main/java/org/opensearch/sql/opensearch/storage/serde/RexStandardizer.java [92-94] if (!allowNumericTypeWiden) { - standardizedOperands = narrowOperandsToOriginalType(call, standardizedOperands, helper); + standardizedOperands = narrowOperandsToOriginalType(call, standardizedOperands, call.operands, helper); } Suggestion importance[1-10]: 2 __ Why: The suggestion raises a concern about unconditional narrowing, but the improved_code doesn't show how to implement the verification. The current logic is intentional per the PR's design: non-arithmetic/non-comparison functions with BIGINT operands are narrowed because they require int parameters in Calcite runtime methods. The suggestion lacks a concrete implementation.	Low

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Persistent review updated to latest commit 0d3b11a