Module transform_hir 

Transformations of SQL IR, before decorrelation.

Statics

NO_PARAMS 🔒

An empty parameter type map.

Functions

column_type 🔒

from_less_existence_predicate 🔒

If sub is a FROM-less subquery (see simplify_from_less_existence_subqueries) whose existence check is correlated on the outer row, returns the predicate p1 AND p2 AND ... expressed in the outer row’s frame. Returns None otherwise.

fuse_window_functions

Aims and scope

relation_contains_subquery 🔒

Returns whether expr contains any subquery (HirScalarExpr::Exists or HirScalarExpr::Select). Both the relation tree and the per-node scalars are traversed iteratively, so this is stack-safe on deeply nested inputs: a long JOIN/CTE chain grows the relation tree, and a flat CASE with many arms lowers to a deep right-nested If chain in a single scalar. visit_pre on HirScalarExpr stops at Exists/Select (they are scalar leaves), so the scan never descends into subquery bodies. The relation walk already yields those bodies as its own children.

resolve_local_columns 🔒

Returns expr with every reference to the current scope (a ColumnRef with level == 0) replaced by its value from env. Returns None if expr cannot be soundly lifted into the outer scope, or references a column absent from env.

simplify_from_less_existence_subqueries

Collapses EXISTS over a FROM-less subquery into an equivalent scalar predicate on the outer row, so that decorrelation produces a plain Filter rather than a semijoin (for EXISTS) or an antijoin (for NOT EXISTS).

split_subquery_predicates

Rewrites predicates that contain subqueries so that the subqueries appear in their own later predicate when possible.

try_simplify_quantified_comparisons

Rewrites quantified comparisons into simpler EXISTS operators.