Optimize the concat_ws function
#3869
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -27,7 +27,7 @@ use datafusion_common::{DFSchema, DataFusionError, Result, ScalarValue}; | |
| use datafusion_expr::expr::BinaryExpr; | ||
| use datafusion_expr::{ | ||
| expr::Between, | ||
| expr_fn::{and, concat_ws, or}, | ||
| expr_rewriter::{ExprRewritable, ExprRewriter, RewriteRecursion}, | ||
| lit, | ||
| logical_plan::LogicalPlan, | ||
|
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@@ -256,6 +256,125 @@ fn negate_clause(expr: Expr) -> Expr { | |
| } | ||
| } | ||
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| /// Simplify the `concat` function by | ||
| /// 1. filtering out all `null` literals | ||
| /// 2. concatenating contiguous literal arguments | ||
| /// | ||
| /// For example: | ||
| /// `concat(col(a), 'hello ', 'world', col(b), null)` | ||
| /// will be optimized to | ||
| /// `concat(col(a), 'hello world', col(b))` | ||
| fn simpl_concat(args: Vec<Expr>) -> Result<Expr> { | ||
| let mut new_args = Vec::with_capacity(args.len()); | ||
| let mut contiguous_scalar = "".to_string(); | ||
| for arg in args { | ||
| match arg { | ||
| // filter out `null` args | ||
| Expr::Literal(ScalarValue::Utf8(None) | ScalarValue::LargeUtf8(None)) => {} | ||
| // All literals have been converted to Utf8 or LargeUtf8 in type_coercion. | ||
| // Concatenate it with the `contiguous_scalar`. | ||
| Expr::Literal( | ||
| ScalarValue::Utf8(Some(v)) | ScalarValue::LargeUtf8(Some(v)), | ||
| ) => contiguous_scalar += &v, | ||
| Expr::Literal(x) => { | ||
| return Err(DataFusionError::Internal(format!( | ||
| "The scalar {} should be casted to string type during the type coercion.", | ||
| x | ||
| ))) | ||
| } | ||
| // If the arg is not a literal, we should first push the current `contiguous_scalar` | ||
| // to the `new_args` (if it is not empty) and reset it to empty string. | ||
| // Then pushing this arg to the `new_args`. | ||
| arg => { | ||
| if !contiguous_scalar.is_empty() { | ||
| new_args.push(lit(contiguous_scalar)); | ||
| contiguous_scalar = "".to_string(); | ||
| } | ||
| new_args.push(arg); | ||
| } | ||
| } | ||
| } | ||
| if !contiguous_scalar.is_empty() { | ||
| new_args.push(lit(contiguous_scalar)); | ||
| } | ||
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| Ok(Expr::ScalarFunction { | ||
| fun: BuiltinScalarFunction::Concat, | ||
| args: new_args, | ||
| }) | ||
| } | ||
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| /// Simply the `concat_ws` function by | ||
| /// 1. folding to `null` if the delimiter is null | ||
| /// 2. filtering out `null` arguments | ||
| /// 3. using `concat` to replace `concat_ws` if the delimiter is an empty string | ||
| /// 4. concatenating contiguous literals if the delimiter is a literal. | ||
| fn simpl_concat_ws(delimiter: &Expr, args: &[Expr]) -> Result<Expr> { | ||
| match delimiter { | ||
| Expr::Literal( | ||
| ScalarValue::Utf8(delimiter) | ScalarValue::LargeUtf8(delimiter), | ||
| ) => { | ||
| match delimiter { | ||
| // when the delimiter is an empty string, | ||
| // we can use `concat` to replace `concat_ws` | ||
| Some(delimiter) if delimiter.is_empty() => simpl_concat(args.to_vec()), | ||
| Some(delimiter) => { | ||
| let mut new_args = Vec::with_capacity(args.len()); | ||
| new_args.push(lit(delimiter)); | ||
| let mut contiguous_scalar = None; | ||
| for arg in args { | ||
| match arg { | ||
| // filter out null args | ||
| Expr::Literal(ScalarValue::Utf8(None) | ScalarValue::LargeUtf8(None)) => {} | ||
| Expr::Literal(ScalarValue::Utf8(Some(v)) | ScalarValue::LargeUtf8(Some(v))) => { | ||
| match contiguous_scalar { | ||
| None => contiguous_scalar = Some(v.to_string()), | ||
| Some(mut pre) => { | ||
| pre += delimiter; | ||
| pre += v; | ||
| contiguous_scalar = Some(pre) | ||
| } | ||
| } | ||
| } | ||
| Expr::Literal(s) => return Err(DataFusionError::Internal(format!("The scalar {} should be casted to string type during the type coercion.", s))), | ||
| // If the arg is not a literal, we should first push the current `contiguous_scalar` | ||
| // to the `new_args` and reset it to None. | ||
| // Then pushing this arg to the `new_args`. | ||
| arg => { | ||
| if let Some(val) = contiguous_scalar { | ||
| new_args.push(lit(val)); | ||
| } | ||
| new_args.push(arg.clone()); | ||
| contiguous_scalar = None; | ||
| } | ||
| } | ||
| } | ||
| if let Some(val) = contiguous_scalar { | ||
| new_args.push(lit(val)); | ||
| } | ||
|
Comment on lines
+325
to
+354
Contributor
There was a problem hiding this comment. This pattern of creating the contiguous scalar is so similar -- I wonder if it could be extracted out into a function -- perhaps as a follow on PR
Contributor
Author
There was a problem hiding this comment. Thank you for reviewing @alamb The logic for |
||
| Ok(Expr::ScalarFunction { | ||
| fun: BuiltinScalarFunction::ConcatWithSeparator, | ||
| args: new_args, | ||
| }) | ||
| } | ||
| // if the delimiter is null, then the value of the whole expression is null. | ||
| None => Ok(Expr::Literal(ScalarValue::Utf8(None))), | ||
| } | ||
| } | ||
| Expr::Literal(d) => Err(DataFusionError::Internal(format!( | ||
| "The scalar {} should be casted to string type during the type coercion.", | ||
| d | ||
| ))), | ||
| d => Ok(concat_ws( | ||
| d.clone(), | ||
| args.iter() | ||
| .cloned() | ||
| .filter(|x| !is_null(x)) | ||
| .collect::<Vec<Expr>>(), | ||
| )), | ||
| } | ||
| } | ||
|
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| impl OptimizerRule for SimplifyExpressions { | ||
| fn name(&self) -> &str { | ||
| "simplify_expressions" | ||
|
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@@ -880,62 +999,19 @@ impl<'a, S: SimplifyInfo> ExprRewriter for Simplifier<'a, S> { | |
| Expr::ScalarFunction { | ||
| fun: BuiltinScalarFunction::Concat, | ||
| args, | ||
| } => simpl_concat(args)?, | ||
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| // concat_ws | ||
| Expr::ScalarFunction { | ||
| fun: BuiltinScalarFunction::ConcatWithSeparator, | ||
| args, | ||
| } => match &args[..] { | ||
| [delimiter, vals @ ..] => simpl_concat_ws(delimiter, vals)?, | ||
| _ => Expr::ScalarFunction { | ||
| fun: BuiltinScalarFunction::ConcatWithSeparator, | ||
| args, | ||
| }, | ||
| }, | ||
|
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| // | ||
| // Rules for Between | ||
|
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@@ -994,6 +1070,7 @@ mod tests { | |
| use chrono::{DateTime, TimeZone, Utc}; | ||
| use datafusion_common::{DFField, DFSchemaRef}; | ||
| use datafusion_expr::expr::Case; | ||
| use datafusion_expr::expr_fn::{concat, concat_ws}; | ||
| use datafusion_expr::logical_plan::table_scan; | ||
| use datafusion_expr::{ | ||
| and, binary_expr, call_fn, col, create_udf, lit, lit_timestamp_nano, | ||
|
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@@ -1379,56 +1456,81 @@ mod tests { | |
| } | ||
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| #[test] | ||
| fn test_simplify_concat_ws() { | ||
| let null = Expr::Literal(ScalarValue::Utf8(None)); | ||
| // the delimiter is not a literal | ||
| { | ||
| let expr = concat_ws(col("c"), vec![lit("a"), null.clone(), lit("b")]); | ||
| let expected = concat_ws(col("c"), vec![lit("a"), lit("b")]); | ||
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| assert_eq!(simplify(expr), expected); | ||
| } | ||
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| // the delimiter is an empty string | ||
| { | ||
| let expr = concat_ws(lit(""), vec![col("a"), lit("c"), lit("b")]); | ||
| let expected = concat(&[col("a"), lit("cb")]); | ||
| assert_eq!(simplify(expr), expected); | ||
| } | ||
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| // the delimiter is a not-empty string | ||
| { | ||
| let expr = concat_ws( | ||
| lit("-"), | ||
| vec![ | ||
| null.clone(), | ||
| col("c0"), | ||
| lit("hello"), | ||
| null.clone(), | ||
| lit("rust"), | ||
| col("c1"), | ||
| lit(""), | ||
| lit(""), | ||
| null, | ||
| ], | ||
| ); | ||
| let expected = concat_ws( | ||
| lit("-"), | ||
| vec![col("c0"), lit("hello-rust"), col("c1"), lit("-")], | ||
| ); | ||
| assert_eq!(simplify(expr), expected) | ||
| } | ||
| } | ||
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| #[test] | ||
| fn test_simplify_concat_ws_with_null() { | ||
| let null = Expr::Literal(ScalarValue::Utf8(None)); | ||
| // null delimiter -> null | ||
| { | ||
| let expr = concat_ws(null.clone(), vec![col("c1"), col("c2")]); | ||
| assert_eq!(simplify(expr), null); | ||
| } | ||
|
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| // filter out null args | ||
| { | ||
| let expr = concat_ws(lit("|"), vec![col("c1"), null.clone(), col("c2")]); | ||
| let expected = concat_ws(lit("|"), vec![col("c1"), col("c2")]); | ||
| assert_eq!(simplify(expr), expected); | ||
| } | ||
|
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| // nested test | ||
| { | ||
| let sub_expr = concat_ws(null.clone(), vec![col("c1"), col("c2")]); | ||
| let expr = concat_ws(lit("|"), vec![sub_expr, col("c3")]); | ||
| assert_eq!(simplify(expr), concat_ws(lit("|"), vec![col("c3")])); | ||
| } | ||
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| // null delimiter (nested) | ||
| { | ||
| let sub_expr = concat_ws(null.clone(), vec![col("c1"), col("c2")]); | ||
| let expr = concat_ws(sub_expr, vec![col("c3"), col("c4")]); | ||
| assert_eq!(simplify(expr), null); | ||
| } | ||
| } | ||
|
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| #[test] | ||
| fn test_simplify_concat() { | ||
| let null = Expr::Literal(ScalarValue::Utf8(None)); | ||
| let expr = concat(&[ | ||
| null.clone(), | ||
| col("c0"), | ||
| lit("hello "), | ||
|
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@@ -1438,7 +1540,7 @@ mod tests { | |
| lit(""), | ||
| null, | ||
| ]); | ||
| let expected = concat(&[col("c0"), lit("hello rust"), col("c1")]); | ||
| assert_eq!(simplify(expr), expected) | ||
| } | ||
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"TIL"
lit()👍