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new 3bc94234 Fix join precedence for non-snowflake queries (#1905)
3bc94234 is described below
commit 3bc94234dfcf73d091c592edd1dab3fdd075ab82
Author: Dima <111751109+dimchi...@users.noreply.github.com>
AuthorDate: Sat Jun 28 19:24:25 2025 +0100
Fix join precedence for non-snowflake queries (#1905)
---
src/dialect/generic.rs | 4 ++++
src/dialect/mod.rs | 28 ++++++++++++++++++++++++++++
src/dialect/snowflake.rs | 4 ++++
src/parser/mod.rs | 6 +++++-
tests/sqlparser_common.rs | 23 +++++++++++++++++++++++
5 files changed, 64 insertions(+), 1 deletion(-)
diff --git a/src/dialect/generic.rs b/src/dialect/generic.rs
index 8f57e487..0b882247 100644
--- a/src/dialect/generic.rs
+++ b/src/dialect/generic.rs
@@ -52,6 +52,10 @@ impl Dialect for GenericDialect {
true
}
+ fn supports_left_associative_joins_without_parens(&self) -> bool {
+ true
+ }
+
fn supports_connect_by(&self) -> bool {
true
}
diff --git a/src/dialect/mod.rs b/src/dialect/mod.rs
index c79b4517..028aa58a 100644
--- a/src/dialect/mod.rs
+++ b/src/dialect/mod.rs
@@ -278,6 +278,34 @@ pub trait Dialect: Debug + Any {
false
}
+ /// Indicates whether the dialect supports left-associative join parsing
+ /// by default when parentheses are omitted in nested joins.
+ ///
+ /// Most dialects (like MySQL or Postgres) assume **left-associative**
precedence,
+ /// so a query like:
+ ///
+ /// ```sql
+ /// SELECT * FROM t1 NATURAL JOIN t5 INNER JOIN t0 ON ...
+ /// ```
+ /// is interpreted as:
+ /// ```sql
+ /// ((t1 NATURAL JOIN t5) INNER JOIN t0 ON ...)
+ /// ```
+ /// and internally represented as a **flat list** of joins.
+ ///
+ /// In contrast, some dialects (e.g. **Snowflake**) assume
**right-associative**
+ /// precedence and interpret the same query as:
+ /// ```sql
+ /// (t1 NATURAL JOIN (t5 INNER JOIN t0 ON ...))
+ /// ```
+ /// which results in a **nested join** structure in the AST.
+ ///
+ /// If this method returns `false`, the parser must build nested join trees
+ /// even in the absence of parentheses to reflect the correct associativity
+ fn supports_left_associative_joins_without_parens(&self) -> bool {
+ true
+ }
+
/// Returns true if the dialect supports the `(+)` syntax for OUTER JOIN.
fn supports_outer_join_operator(&self) -> bool {
false
diff --git a/src/dialect/snowflake.rs b/src/dialect/snowflake.rs
index 5ebb7e37..ba28a8ec 100644
--- a/src/dialect/snowflake.rs
+++ b/src/dialect/snowflake.rs
@@ -283,6 +283,10 @@ impl Dialect for SnowflakeDialect {
true
}
+ fn supports_left_associative_joins_without_parens(&self) -> bool {
+ false
+ }
+
fn is_reserved_for_identifier(&self, kw: Keyword) -> bool {
// Unreserve some keywords that Snowflake accepts as identifiers
// See: https://docs.snowflake.com/en/sql-reference/reserved-keywords
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index adf50a8f..a079488f 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -12495,7 +12495,11 @@ impl<'a> Parser<'a> {
};
let mut relation = self.parse_table_factor()?;
- if self.peek_parens_less_nested_join() {
+ if !self
+ .dialect
+ .supports_left_associative_joins_without_parens()
+ && self.peek_parens_less_nested_join()
+ {
let joins = self.parse_joins()?;
relation = TableFactor::NestedJoin {
table_with_joins: Box::new(TableWithJoins { relation,
joins }),
diff --git a/tests/sqlparser_common.rs b/tests/sqlparser_common.rs
index 17b46e6f..f6f51459 100644
--- a/tests/sqlparser_common.rs
+++ b/tests/sqlparser_common.rs
@@ -15359,6 +15359,29 @@ fn check_enforced() {
);
}
+#[test]
+fn join_precedence() {
+ all_dialects_except(|d|
!d.supports_left_associative_joins_without_parens())
+ .verified_query_with_canonical(
+ "SELECT *
+ FROM t1
+ NATURAL JOIN t5
+ INNER JOIN t0 ON (t0.v1 + t5.v0) > 0
+ WHERE t0.v1 = t1.v0",
+ // canonical string without parentheses
+ "SELECT * FROM t1 NATURAL JOIN t5 INNER JOIN t0 ON (t0.v1 + t5.v0) > 0
WHERE t0.v1 = t1.v0",
+ );
+ all_dialects_except(|d|
d.supports_left_associative_joins_without_parens()).verified_query_with_canonical(
+ "SELECT *
+ FROM t1
+ NATURAL JOIN t5
+ INNER JOIN t0 ON (t0.v1 + t5.v0) > 0
+ WHERE t0.v1 = t1.v0",
+ // canonical string with parentheses
+ "SELECT * FROM t1 NATURAL JOIN (t5 INNER JOIN t0 ON (t0.v1 + t5.v0) >
0) WHERE t0.v1 = t1.v0",
+ );
+}
+
#[test]
fn parse_create_procedure_with_language() {
let sql = r#"CREATE PROCEDURE test_proc LANGUAGE sql AS BEGIN SELECT 1;
END"#;
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