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pushdown_predicates

polyglot_sql::optimizer::pushdown_predicates

Function pushdown_predicates 

Source 
pub fn pushdown_predicates(
    expression: Expression,
    dialect: Option<DialectType>,
) -> Expression
Expand description

Rewrite SQL AST to pushdown predicates in FROMs and JOINs.

§Example

-- Before:
SELECT y.a AS a FROM (SELECT x.a AS a FROM x AS x) AS y WHERE y.a = 1
-- After:
SELECT y.a AS a FROM (SELECT x.a AS a FROM x AS x WHERE x.a = 1) AS y WHERE TRUE

§Arguments

  • expression - The expression to optimize
  • dialect - Optional dialect for dialect-specific behavior

§Returns

The optimized expression with predicates pushed down