Module scalar_udf 

Scalar SQL-expression user functions, expanded (inlined) into native SQL before planning.

A scalar SQL function such as CREATE FUNCTION tax(x DOUBLE) RETURNS DOUBLE RETURN x * 1.1 is stored as a parsed body expression plus its parameter names. When a query references it (SELECT tax(amount) FROM sales), every call is replaced with the body — arguments substituted for parameters — so the query becomes pure native SQL (SELECT (amount * 1.1) FROM sales).

Because the result is ordinary SQL with no UDF reference, it plans and runs anywhere the engine runs, INCLUDING distributed execution on the Rust executors — no Python interpreter and no per-executor function registration required. This is the portable, distributable counterpart to Python-callable UDFs, which can only run in the embedded (in-process) engine.

Structs

ScalarSqlFunction

A scalar SQL function definition: its (lower-cased) name, ordered parameter names, and the parsed body expression.

Functions

expand_scalar_sql_functions

Inline every call to a registered scalar SQL function in sql, returning pure native SQL. No-op (returns sql unchanged) when funcs is empty or the query references none of them. Errors only if the query cannot be parsed.