StarRocks FE Type System (fe-type)

This module contains the Frontend (FE) logical type system. It defines the full set of SQL-visible types and related helpers used by the analyzer, optimizer, catalog, and planner.

Responsibilities

• Define the type hierarchy in com.starrocks.type:
  • Core: Type, ScalarType, PrimitiveType
  • Complex: ArrayType, MapType, StructType, StructField, JsonType
  • String and binary: CharType, VarcharType, StringType, VarbinaryType
  • Numerics and date/time: IntegerType, FloatType, DecimalType, DateType
  • Special/aggregate: BitmapType, HLLType, PercentileType, FunctionType, VariantType, AggStateDesc
  • Wildcards and helpers: Any* types, ComplexTypeAccessPath, ComplexTypeAccessPathType
• Keep this module free of FE business logic; it is a pure model layer used across FE.

Relationship to other FE modules

• Construction entry points live in fe/fe-core via TypeFactory (e.g., TypeFactory.createCharType, createUnifiedDecimalType, createDecimalV3Type, etc.).
• Analyzer, optimizer, catalog, and planner consume com.starrocks.type.* from this module.
• Connectors/plugins should not expose FE types over SPI; avoid leaking com.starrocks.type.* across SPI boundaries.

Decimal notes

• Decimal V2 vs V3 is selected by configuration (Config.enable_decimal_v3).
• Large precision handling may fall back to DOUBLE or cap to DECIMAL256 based on session variables (see TypeFactory).

Usage examples

• Prefer factory methods in FE core:
  • TypeFactory.createCharType(10)
  • TypeFactory.createVarcharType(255)
  • TypeFactory.createUnifiedDecimalType(10, 2)
  • new ArrayType(TypeFactory.createVarcharType(100))

Development guidelines

• Do not add FE-specific behavior or I/O here; keep types immutable except for well-scoped, package-private setters used by TypeFactory.
• Respect Type.MAX_NESTING_DEPTH to avoid pathological structures.

References

• FE overview: fe/README.md
• FE core factory: fe/fe-core/src/main/java/com/starrocks/type/TypeFactory.java
• Package: com.starrocks.type