From 8d4569ad32a0f6bdacc866f6e3acb5d6d3a1e17e Mon Sep 17 00:00:00 2001
From: LucaCappelletti94 <cappelletti.luca94@gmail.com>
Date: Tue, 27 Oct 2026 10:55:05 +0100
Subject: [PATCH 1/2] PostgreSQL: Parse NULLS [NOT] DISTINCT on column UNIQUE
 constraints

---
 src/ast/ddl.rs              |  8 ++++++--
 src/parser/mod.rs           |  3 ++-
 tests/sqlparser_postgres.rs | 38 +++++++++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/src/ast/ddl.rs b/src/ast/ddl.rs
index c1780e2a43..61a4d4002a 100644
--- a/src/ast/ddl.rs
+++ b/src/ast/ddl.rs
@@ -1978,7 +1978,7 @@ pub enum ColumnOption {
 
     /// `PRIMARY KEY [<constraint_characteristics>]`
     PrimaryKey(PrimaryKeyConstraint),
-    /// `UNIQUE [<constraint_characteristics>]`
+    /// `UNIQUE [NULLS [NOT] DISTINCT] [<constraint_characteristics>]`
     Unique(UniqueConstraint),
     /// A referential integrity constraint (`REFERENCES <foreign_table> (<referred_columns>)
     /// [ MATCH { FULL | PARTIAL | SIMPLE } ]
@@ -2113,7 +2113,11 @@ impl fmt::Display for ColumnOption {
                 Ok(())
             }
             Unique(constraint) => {
-                write!(f, "UNIQUE{:>}", constraint.index_type_display)?;
+                write!(
+                    f,
+                    "UNIQUE{:>}{}",
+                    constraint.index_type_display, constraint.nulls_distinct
+                )?;
                 if let Some(characteristics) = &constraint.characteristics {
                     write!(f, " {characteristics}")?;
                 }
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index c5a6f4e854..53f54a048b 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -10129,6 +10129,7 @@ impl<'a> Parser<'a> {
                 } else {
                     KeyOrIndexDisplay::None
                 };
+            let nulls_distinct = self.parse_optional_nulls_distinct()?;
             let characteristics = self.parse_constraint_characteristics()?;
             Ok(Some(
                 UniqueConstraint {
@@ -10140,7 +10141,7 @@ impl<'a> Parser<'a> {
                     include: vec![],
                     index_options: vec![],
                     characteristics,
-                    nulls_distinct: NullsDistinctOption::None,
+                    nulls_distinct,
                 }
                 .into(),
             ))
diff --git a/tests/sqlparser_postgres.rs b/tests/sqlparser_postgres.rs
index 11a4703f55..df88c26b7b 100644
--- a/tests/sqlparser_postgres.rs
+++ b/tests/sqlparser_postgres.rs
@@ -11057,3 +11057,41 @@ fn parse_role_signed_connection_limit() {
         "sql parser error: Expected: option, found: CONNECTION"
     );
 }
+
+#[test]
+fn parse_create_table_column_unique_nulls_distinct() {
+    let Statement::CreateTable(CreateTable { columns, .. }) = pg_and_generic().verified_stmt(
+        "CREATE TABLE t (u INT UNIQUE NULLS NOT DISTINCT, v INT UNIQUE NULLS DISTINCT, w INT UNIQUE)",
+    ) else {
+        panic!("Expected CREATE TABLE");
+    };
+    let nulls_distinct: Vec<_> = columns
+        .iter()
+        .map(|column| match &column.options[..] {
+            [ColumnOptionDef {
+                option: ColumnOption::Unique(constraint),
+                ..
+            }] => &constraint.nulls_distinct,
+            options => panic!("Expected one UNIQUE option, got {options:?}"),
+        })
+        .collect();
+    assert_eq!(
+        nulls_distinct,
+        vec![
+            &NullsDistinctOption::NotDistinct,
+            &NullsDistinctOption::Distinct,
+            &NullsDistinctOption::None,
+        ]
+    );
+
+    pg_and_generic().verified_stmt(
+        "CREATE TABLE t (u INT CONSTRAINT k UNIQUE NULLS NOT DISTINCT DEFERRABLE NOT NULL)",
+    );
+
+    assert_eq!(
+        pg_and_generic()
+            .parse_sql_statements("CREATE TABLE t (u INT UNIQUE NULLS NOT)")
+            .unwrap_err(),
+        ParserError::ParserError("Expected: DISTINCT, found: )".to_string())
+    );
+}

From 9e652602a969f5e1794482842372414f2d800b59 Mon Sep 17 00:00:00 2001
From: LucaCappelletti94 <cappelletti.luca94@gmail.com>
Date: Wed, 28 Oct 2026 13:35:47 +0100
Subject: [PATCH 2/2] Test formatter error propagation for column UNIQUE NULLS
 DISTINCT

---
 tests/sqlparser_postgres.rs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tests/sqlparser_postgres.rs b/tests/sqlparser_postgres.rs
index df88c26b7b..a21435b00f 100644
--- a/tests/sqlparser_postgres.rs
+++ b/tests/sqlparser_postgres.rs
@@ -11095,3 +11095,23 @@ fn parse_create_table_column_unique_nulls_distinct() {
         ParserError::ParserError("Expected: DISTINCT, found: )".to_string())
     );
 }
+
+#[test]
+fn display_column_unique_nulls_distinct_propagates_formatter_errors() {
+    use core::fmt::{self, Write};
+
+    struct RejectingWriter;
+
+    impl Write for RejectingWriter {
+        fn write_str(&mut self, value: &str) -> fmt::Result {
+            if value.contains("NULLS") {
+                Err(fmt::Error)
+            } else {
+                Ok(())
+            }
+        }
+    }
+
+    let stmt = pg_and_generic().verified_stmt("CREATE TABLE t (u INT UNIQUE NULLS NOT DISTINCT)");
+    assert_eq!(write!(RejectingWriter, "{stmt}"), Err(fmt::Error));
+}