MohamedAbdeen21 commented on code in PR #11186:
URL: https://github.com/apache/datafusion/pull/11186#discussion_r1667722385
##########
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:
Since the primary goal is pushdown for other systems, we have two options.
1. Completely ignore this issue. Systems can have very different precedence
rules, and therefore, we can not guarantee correctness once some parentheses
are removed. Also, it can be hard to decide which parentheses are "safe" to
remove.
2. Informing DF of your target system operator precedence through
implementing a dialect. This can be a lot of work for the dev, but I can see
this being a desired option for some people; as Phillip pointed out, It can
make debugging easier.
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