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Posted to github@arrow.apache.org by "Weijun-H (via GitHub)" <gi...@apache.org> on 2023/03/31 22:16:37 UTC
[GitHub] [arrow-datafusion] Weijun-H opened a new pull request, #5819: feat: Add expression rewrite rules for LIKE and ILIKE
Weijun-H opened a new pull request, #5819:
URL: https://github.com/apache/arrow-datafusion/pull/5819
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Closes #5817
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[GitHub] [arrow-datafusion] alamb merged pull request #5819: feat: Add expression rewrite rules for LIKE and ILIKE
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb merged PR #5819:
URL: https://github.com/apache/arrow-datafusion/pull/5819
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[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #5819: feat: Add expression rewrite rules for LIKE and ILIKE
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb commented on code in PR #5819:
URL: https://github.com/apache/arrow-datafusion/pull/5819#discussion_r1156145218
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -2320,16 +2337,10 @@ mod tests {
assert_no_change(regex_match(col("c1"), lit("f_o")));
// empty cases
- assert_change(regex_match(col("c1"), lit("")), like(col("c1"), "%"));
Review Comment:
I double checked that datafusion got the right answer, both before and after this PR:
```shell
❯ select regexp_match('foo', '');
+-----------------------------------+
| regexpmatch(Utf8("foo"),Utf8("")) |
+-----------------------------------+
| [] |
+-----------------------------------+
1 row in set. Query took 0.000 seconds.
```
So things look ok
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[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #5819: feat: Add expression rewrite rules for LIKE and ILIKE
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb commented on code in PR #5819:
URL: https://github.com/apache/arrow-datafusion/pull/5819#discussion_r1156136411
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -1118,6 +1119,36 @@ impl<'a, S: SimplifyInfo> TreeNodeRewriter for Simplifier<'a, S> {
right,
}) => simplify_regex_expr(left, op, right)?,
+ // Rules for Like
+ Expr::Like(Like {
+ expr,
+ pattern,
+ negated,
+ escape_char: _,
+ }) if !is_null(&expr)
+ && matches!(
+ pattern.as_ref(),
+ Expr::Literal(ScalarValue::Utf8(Some(pattern_str))) if pattern_str == "%"
Review Comment:
👍
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[GitHub] [arrow-datafusion] alamb commented on pull request #5819: feat: Add expression rewrite rules for LIKE and ILIKE
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb commented on PR #5819:
URL: https://github.com/apache/arrow-datafusion/pull/5819#issuecomment-1494566679
Thanks again @Weijun-H
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[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #5819: feat: Add expression rewrite rules for LIKE and ILIKE
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb commented on code in PR #5819:
URL: https://github.com/apache/arrow-datafusion/pull/5819#discussion_r1155093800
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -1118,6 +1119,22 @@ impl<'a, S: SimplifyInfo> TreeNodeRewriter for Simplifier<'a, S> {
right,
}) => simplify_regex_expr(left, op, right)?,
+ // Rules for Like
+ Expr::Like(Like {
+ expr,
+ pattern,
+ negated,
+ escape_char: _,
+ }) if !is_null(&expr) && pattern.eq(&Box::new(lit("%"))) => lit(!negated),
Review Comment:
By writing `Box::new(...)` I think this is goign to do two allocations each time (one for the Box and one for the String in the literal)
Would it be possible to rewrite this to a match statement without allocation?
```rust
matches!(pattern.as_ref(), Expression::Literal(ScalarValue::Utf8(..)))
```
?
You might have to define some better way to check for the literal scalar
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -2320,16 +2337,10 @@ mod tests {
assert_no_change(regex_match(col("c1"), lit("f_o")));
// empty cases
- assert_change(regex_match(col("c1"), lit("")), like(col("c1"), "%"));
Review Comment:
🤔 the original rewrite rule looks incorrect to me (as in the orignal rule shouldn't be rewriting regexp match). We can fix this in some other PR
```sql
postgres=# select regexp_match('foo', '');
regexp_match
--------------
{""}
(1 row)
postgres=# select like('foo', '%');
like
------
t
(1 row)
```
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -2851,4 +2838,70 @@ mod tests {
or(col("c2").lt(lit(3)), col("c2").gt(lit(4)))
);
}
+
+ #[test]
+ fn test_like_and_ilke() {
+ // test non-null values
+ let expr = Expr::Like(Like::new(
+ false,
+ Box::new(col("c1")),
+ Box::new(lit("%")),
+ None,
+ ));
Review Comment:
What do you think about using the expr_fn's style for creating `like` https://docs.rs/datafusion/latest/datafusion/prelude/enum.Expr.html#method.like
```suggestion
let expr = like(col("c1"), lit("%"));
```
I think that would make it clearer what cases these tests were covering
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[GitHub] [arrow-datafusion] Weijun-H commented on a diff in pull request #5819: feat: Add expression rewrite rules for LIKE and ILIKE
Posted by "Weijun-H (via GitHub)" <gi...@apache.org>.
Weijun-H commented on code in PR #5819:
URL: https://github.com/apache/arrow-datafusion/pull/5819#discussion_r1155105069
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -2851,4 +2838,70 @@ mod tests {
or(col("c2").lt(lit(3)), col("c2").gt(lit(4)))
);
}
+
+ #[test]
+ fn test_like_and_ilke() {
+ // test non-null values
+ let expr = Expr::Like(Like::new(
+ false,
+ Box::new(col("c1")),
+ Box::new(lit("%")),
+ None,
+ ));
Review Comment:
Yes, it is a better way. I forgot to use it 😄
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