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Simplify concat_ws(null, ..) to null #3608

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Merged
alamb merged 4 commits into from
Sep 26, 2022
Merged

Simplify concat_ws(null, ..) to null #3608

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e0e3de5
simpl when seprartor is null
HaoYang670 Sep 25, 2022
b055bf5
fix clippy
HaoYang670 Sep 25, 2022
add7e10
check nulls in other positions are not simplified to scalar null
HaoYang670 Sep 25, 2022
d14b01f
fmt
HaoYang670 Sep 25, 2022
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62 changes: 59 additions & 3 deletions datafusion/optimizer/src/simplify_expressions.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -26,12 +26,11 @@ use arrow::record_batch::RecordBatch;
use datafusion_common::{DFSchema, DFSchemaRef, DataFusionError, Result, ScalarValue};
use datafusion_expr::{
expr_fn::{and, or},
expr_rewriter::RewriteRecursion,
expr_rewriter::{ExprRewritable, ExprRewriter},
expr_rewriter::{ExprRewritable, ExprRewriter, RewriteRecursion},
lit,
logical_plan::LogicalPlan,
utils::from_plan,
ColumnarValue, Expr, ExprSchemable, Operator, Volatility,
BuiltinScalarFunction, ColumnarValue, Expr, ExprSchemable, Operator, Volatility,
};
use datafusion_physical_expr::{create_physical_expr, execution_props::ExecutionProps};
use std::sync::Arc;
Expand Down Expand Up @@ -816,6 +815,23 @@ impl<'a, S: SimplifyInfo> ExprRewriter for Simplifier<'a, S> {
out_expr.rewrite(self)?
}

// concat_ws

@alamb alamb Sep 25, 2022

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Suggested change
// concat_ws
// concat_ws
// If any of the arguments is NULL, the output will be null

ScalarFunction {
fun: BuiltinScalarFunction::ConcatWithSeparator,
args,
} => {
match &args[..] {
[Expr::Literal(sp), ..] if sp.is_null() => {
Expr::Literal(ScalarValue::Utf8(None))
}
// TODO https://github.com/apache/arrow-datafusion/issues/3599
_ => ScalarFunction {
fun: BuiltinScalarFunction::ConcatWithSeparator,
args,
},
}
}

//
// Rules for Between
//
Expand Down Expand Up @@ -1132,6 +1148,46 @@ mod tests {
assert_eq!(simplify(expr_plus), lit(2_i64));
}

#[test]
fn test_simplify_concat_ws_null_separator() {
fn build_concat_ws_expr(args: &[Expr]) -> Expr {
Expr::ScalarFunction {
fun: BuiltinScalarFunction::ConcatWithSeparator,
args: args.to_vec(),
}
}

let null = Expr::Literal(ScalarValue::Utf8(None));
// simple test
{
let expr = build_concat_ws_expr(&[null.clone(), col("c1"), col("c2")]);
assert_eq!(simplify(expr), null);
}

Comment thread
alamb marked this conversation as resolved.
// NULLs in other positions are not simplified.
{
let expr = build_concat_ws_expr(&[lit("|"), null.clone(), col("c2")]);
assert_eq!(simplify(expr.clone()), expr);
}

// nested test
{
let sub_expr = build_concat_ws_expr(&[null.clone(), col("c1"), col("c2")]);
let expr = build_concat_ws_expr(&[lit("|"), sub_expr, col("c3")]);
assert_eq!(
simplify(expr),
build_concat_ws_expr(&[lit("|"), null.clone(), col("c3")])
);
}

// nested test -- separator
{
let sub_expr = build_concat_ws_expr(&[null.clone(), col("c1"), col("c2")]);
let expr = build_concat_ws_expr(&[sub_expr, col("c3"), col("c4")]);
assert_eq!(simplify(expr), null);
}
}

// ------------------------------
// --- ConstEvaluator tests -----
// ------------------------------
Expand Down