Module subquery 

Subquery planning: IN (SELECT …), NOT IN (SELECT …), scalar subqueries.

Rewrites WHERE-clause subqueries into semi/anti joins so the existing hash-join executor handles them without a dedicated subquery engine.

Supported patterns:

• WHERE col IN (SELECT col2 FROM tbl ...) → semi-join
• WHERE col NOT IN (SELECT col2 FROM tbl ...) → anti-join
• WHERE col > (SELECT AGG(...) FROM tbl ...) → scalar subquery (materialized)

Structs

SubqueryExtraction

Result of extracting subqueries from a WHERE clause.

SubqueryJoin

A subquery that was rewritten as a join.

Functions

extract_subqueries

Extract IN (SELECT ...) and NOT IN (SELECT ...) patterns from a WHERE clause.