Module annotate_types 

Type annotation pass for SQL expressions.

Infers and propagates SQL data types across AST nodes using schema metadata. Inspired by Python sqlglot’s annotate_types optimizer pass.

Overview

The pass walks the AST bottom-up, resolving types for:

• Literals: 42 → Int, 'hello' → Varchar, TRUE → Boolean
• Column references: looked up from the provided Schema
• Binary operators: result type from operand coercion (e.g. INT + FLOAT → FLOAT)
• CAST / TRY_CAST: the target data type
• Functions: return type based on function signature and argument types
• CASE: common type across all THEN / ELSE branches
• Aggregates: COUNT → BigInt, SUM depends on input, etc.
• Subqueries: type of the single output column

Example

use sqlglot_rust::optimizer::annotate_types::annotate_types;
use sqlglot_rust::schema::{MappingSchema, Schema};
use sqlglot_rust::ast::DataType;
use sqlglot_rust::{parse, Dialect};

let mut schema = MappingSchema::new(Dialect::Ansi);
schema.add_table(&["t"], vec![
    ("id".to_string(), DataType::Int),
    ("name".to_string(), DataType::Varchar(Some(255))),
]).unwrap();

let stmt = parse("SELECT id, name FROM t WHERE id > 1", Dialect::Ansi).unwrap();
let annotations = annotate_types(&stmt, &schema);
// annotations now contains inferred types for every expression node

Structs

TypeAnnotations

Stores inferred DataType annotations for expression nodes in an AST.

Functions

annotate_types

Annotate all expression nodes in a statement with inferred SQL types.