goldmedal commented on code in PR #11186:
URL: https://github.com/apache/datafusion/pull/11186#discussion_r1667004917
##########
datafusion/sql/tests/cases/plan_to_sql.rs:
##########
@@ -314,3 +310,78 @@ fn test_table_references_in_plan_to_sql() {
"SELECT \"table\".id, \"table\".\"value\" FROM \"table\"",
);
}
+
+#[test]
+fn test_pretty_roundtrip() -> Result<()> {
+ let schema = Schema::new(vec![
+ Field::new("id", DataType::Utf8, false),
+ Field::new("age", DataType::Utf8, false),
+ ]);
+
+ let df_schema = DFSchema::try_from(schema)?;
+
+ let context = MockContextProvider::default();
+ let sql_to_rel = SqlToRel::new(&context);
+
+ let unparser = Unparser::default();
+
+ let sql_to_pretty_unparse = vec![
+ ("((id < 5) OR (age = 8))", "id < 5 OR age = 8"),
+ ("((id + 5) * (age * 8))", "(id + 5) * age * 8"),
+ ("(3 + (5 * 6) * 3)", "3 + 5 * 6 * 3"),
+ ("((3 * (5 + 6)) * 3)", "3 * (5 + 6) * 3"),
+ ("((3 AND (5 OR 6)) * 3)", "(3 AND (5 OR 6)) * 3"),
+ ("((3 + (5 + 6)) * 3)", "(3 + 5 + 6) * 3"),
+ ("((3 + (5 + 6)) + 3)", "3 + 5 + 6 + 3"),
+ ("3 + 5 + 6 + 3", "3 + 5 + 6 + 3"),
+ ("3 + (5 + (6 + 3))", "3 + 5 + 6 + 3"),
+ ("3 + ((5 + 6) + 3)", "3 + 5 + 6 + 3"),
+ ("(3 + 5) + (6 + 3)", "3 + 5 + 6 + 3"),
+ ("((3 + 5) + (6 + 3))", "3 + 5 + 6 + 3"),
+ (
+ "((id > 10) OR (age BETWEEN 10 AND 20))",
+ "id > 10 OR age BETWEEN 10 AND 20",
+ ),
+ (
+ "((id > 10) * (age BETWEEN 10 AND 20))",
+ "(id > 10) * (age BETWEEN 10 AND 20)",
+ ),
+ ("id - (age - 8)", "id - (age - 8)"),
+ ("((id - age) - 8)", "id - age - 8"),
+ ("(id OR (age - 8))", "id OR age - 8"),
+ ("(id / (age - 8))", "id / (age - 8)"),
+ ("((id / age) * 8)", "id / age * 8"),
+ ("((age + 10) < 20) IS TRUE", "(age + 10 < 20) IS TRUE"),
+ (
+ "(20 > (age + 5)) IS NOT FALSE",
+ "(20 > age + 5) IS NOT FALSE",
+ ),
+ ("(true AND false) IS FALSE", "(true AND false) IS FALSE"),
+ ("true AND (false IS FALSE)", "true AND false IS FALSE"),
+ ];
+
+ for (sql, pretty) in sql_to_pretty_unparse.iter() {
+ let sql_expr = Parser::new(&GenericDialect {})
+ .try_with_sql(sql)?
+ .parse_expr()?;
+ let expr =
+ sql_to_rel.sql_to_expr(sql_expr, &df_schema, &mut
PlannerContext::new())?;
+ let round_trip_sql = unparser.expr_to_sql(&expr)?.to_string();
+ assert_eq!(pretty.to_string(), round_trip_sql);
+
+ // verify that the pretty string parses to the same underlying Expr
+ let pretty_sql_expr = Parser::new(&GenericDialect {})
+ .try_with_sql(pretty)?
+ .parse_expr()?;
+
+ let pretty_expr = sql_to_rel.sql_to_expr(
+ pretty_sql_expr,
+ &df_schema,
+ &mut PlannerContext::new(),
+ )?;
+
+ assert_eq!(expr.to_string(), pretty_expr.to_string());
Review Comment:
I think it's related to
https://github.com/apache/datafusion/pull/11186#discussion_r1664797700. If our
main purpose is providing SQL for full pushdown to other data sources, this
behavior makes sense to me. For my current project (Wren), it's acceptable.
However, if our purpose is human readability, I think preserving the
semantics is important. Maybe we can just remove the outermost brackets
(they're exactly redundant) for a calculation expression like:
```
((3 + (5 + 6)) + 3) -> (3 + (5 + 6)) + 3
```
I'm not sure, but I think it might be more similar to what a human would
write.
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