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fix: not do boolean folding on NULL and/or expr #1245

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merged 2 commits into from
Nov 5, 2021
Merged

fix: not do boolean folding on NULL and/or expr #1245

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d3550ff
fix: not do boolean folding on NULL and/or expr
NGA-TRAN Nov 5, 2021
c965c9c
refactor: address review comments
NGA-TRAN Nov 5, 2021
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186 changes: 118 additions & 68 deletions datafusion/src/optimizer/constant_folding.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,94 @@ impl<'a> Simplifier<'a> {

false
}

fn boolean_folding_for_or(
const_bool: &Option<bool>,
bool_expr: Box<Expr>,
left_right_order: bool,
) -> Expr {
// See if we can fold 'const_bool OR bool_expr' to a constant boolean
match const_bool {
// TRUE or expr (including NULL) = TRUE
Some(true) => Expr::Literal(ScalarValue::Boolean(Some(true))),
// FALSE or expr (including NULL) = expr
Some(false) => *bool_expr,
None => match *bool_expr {
// NULL or TRUE = TRUE
Expr::Literal(ScalarValue::Boolean(Some(true))) => {
Expr::Literal(ScalarValue::Boolean(Some(true)))
}
// NULL or FALSE = NULL
Expr::Literal(ScalarValue::Boolean(Some(false))) => {
Expr::Literal(ScalarValue::Boolean(None))
}
// NULL or NULL = NULL
Expr::Literal(ScalarValue::Boolean(None)) => {
Expr::Literal(ScalarValue::Boolean(None))
}
// NULL or expr can be either NULL or TRUE
// So let us not rewrite it
_ => {
let mut left =
Box::new(Expr::Literal(ScalarValue::Boolean(*const_bool)));
let mut right = bool_expr;
if !left_right_order {
std::mem::swap(&mut left, &mut right);
}

Expr::BinaryExpr {
left,
op: Operator::Or,
right,
}
}
},
}
}

fn boolean_folding_for_and(
const_bool: &Option<bool>,
bool_expr: Box<Expr>,
left_right_order: bool,
) -> Expr {
// See if we can fold 'const_bool AND bool_expr' to a constant boolean
match const_bool {
// TRUE and expr (including NULL) = expr
Some(true) => *bool_expr,
// FALSE and expr (including NULL) = FALSE
Some(false) => Expr::Literal(ScalarValue::Boolean(Some(false))),
None => match *bool_expr {
// NULL and TRUE = NULL
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FWIW I am working on getting these constant cases to work with the ConstEvaluator (so they wouldn't be strictly necessary) but it turns out these types of expressions don't actually work in the general evaluator

I am working on it in #1163

But in any event I think this code is good 👍

Expr::Literal(ScalarValue::Boolean(Some(true))) => {
Expr::Literal(ScalarValue::Boolean(None))
}
// NULL and FALSE = FALSE
Expr::Literal(ScalarValue::Boolean(Some(false))) => {
Expr::Literal(ScalarValue::Boolean(Some(false)))
}
// NULL and NULL = NULL
Expr::Literal(ScalarValue::Boolean(None)) => {
Expr::Literal(ScalarValue::Boolean(None))
}
// NULL and expr can either be NULL or FALSE
// So let us not rewrite it
_ => {
let mut left =
Box::new(Expr::Literal(ScalarValue::Boolean(*const_bool)));
let mut right = bool_expr;
if !left_right_order {
std::mem::swap(&mut left, &mut right);
}

Expr::BinaryExpr {
left,
op: Operator::And,
right,
}
}
},
}
}
}

impl<'a> ExprRewriter for Simplifier<'a> {
Expand Down Expand Up @@ -214,46 +302,12 @@ impl<'a> ExprRewriter for Simplifier<'a> {
(Expr::Literal(ScalarValue::Boolean(b)), _)
if self.is_boolean_type(&right) =>
{
match b {
Some(true) => Expr::Literal(ScalarValue::Boolean(Some(true))),
Some(false) => match *right {
Expr::Literal(ScalarValue::Boolean(None)) => {
Expr::Literal(ScalarValue::Boolean(None))
}
_ => *right,
},
None => match *right {
Expr::Literal(ScalarValue::Boolean(Some(true))) => {
Expr::Literal(ScalarValue::Boolean(Some(true)))
}
Expr::Literal(ScalarValue::Boolean(Some(false))) => {
Expr::Literal(ScalarValue::Boolean(None))
}
_ => *right,
},
}
Self::boolean_folding_for_or(b, right, true)
}
(_, Expr::Literal(ScalarValue::Boolean(b)))
if self.is_boolean_type(&left) =>
{
match b {
Some(true) => Expr::Literal(ScalarValue::Boolean(Some(true))),
Some(false) => match *left {
Expr::Literal(ScalarValue::Boolean(None)) => {
Expr::Literal(ScalarValue::Boolean(None))
}
_ => *left,
},
None => match *left {
Expr::Literal(ScalarValue::Boolean(Some(true))) => {
Expr::Literal(ScalarValue::Boolean(Some(true)))
}
Expr::Literal(ScalarValue::Boolean(Some(false))) => {
Expr::Literal(ScalarValue::Boolean(None))
}
_ => *left,
},
}
Self::boolean_folding_for_or(b, left, false)
}
_ => Expr::BinaryExpr {
left,
Expand All @@ -265,42 +319,12 @@ impl<'a> ExprRewriter for Simplifier<'a> {
(Expr::Literal(ScalarValue::Boolean(b)), _)
if self.is_boolean_type(&right) =>
{
// match b {
// Some(false) => {
// Expr::Literal(ScalarValue::Boolean(Some(false)))
// }
// _ => *right,
// }
match b {
Some(true) => match *right {
Expr::Literal(ScalarValue::Boolean(None)) => {
Expr::Literal(ScalarValue::Boolean(None))
}
_ => *right,
},
Some(false) => {
Expr::Literal(ScalarValue::Boolean(Some(false)))
}
None => match *right {
Expr::Literal(ScalarValue::Boolean(Some(true))) => {
Expr::Literal(ScalarValue::Boolean(None))
}
Expr::Literal(ScalarValue::Boolean(Some(false))) => {
Expr::Literal(ScalarValue::Boolean(Some(false)))
}
_ => *right,
},
}
Self::boolean_folding_for_and(b, right, true)
}
(_, Expr::Literal(ScalarValue::Boolean(b)))
if self.is_boolean_type(&left) =>
{
match b {
Some(false) => {
Expr::Literal(ScalarValue::Boolean(Some(false)))
}
_ => *left,
}
Self::boolean_folding_for_and(b, left, false)
}
_ => Expr::BinaryExpr {
left,
Expand Down Expand Up @@ -962,6 +986,19 @@ mod tests {
lit(ScalarValue::Boolean(None)),
);

// ( c1 BETWEEN Int32(0) AND Int32(10) ) OR Boolean(NULL)
// it can be either NULL or TRUE depending on the value of `c1 BETWEEN Int32(0) AND Int32(10)`
// and should not be rewritten
let expr = Expr::Between {
expr: Box::new(col("c1")),
negated: false,
low: Box::new(lit(0)),
high: Box::new(lit(10)),
};
let expr = expr.or(Expr::Literal(ScalarValue::Boolean(None)));
let result = expr.clone().rewrite(&mut rewriter)?;
assert_eq!(expr, result);

Ok(())
}
#[test]
Expand Down Expand Up @@ -1016,6 +1053,19 @@ mod tests {
lit(ScalarValue::Boolean(Some(false))),
);

// c1 BETWEEN Int32(0) AND Int32(10) AND Boolean(NULL)
// it can be either NULL or FALSE depending on the value of `c1 BETWEEN Int32(0) AND Int32(10`
// and should not be rewritten
let expr = Expr::Between {
expr: Box::new(col("c1")),
negated: false,
low: Box::new(lit(0)),
high: Box::new(lit(10)),
};
let expr = expr.and(Expr::Literal(ScalarValue::Boolean(None)));
let result = expr.clone().rewrite(&mut rewriter)?;
assert_eq!(expr, result);

Ok(())
}
}