Redshift alter column type no set (#1912)

Author: yoavcloud

src/ast/ddl.rs

@@ -893,7 +893,10 @@ pub enum AlterColumnOperation {
         data_type: DataType,
         /// PostgreSQL specific
         using: Option<Expr>,
+        /// Set to true if the statement includes the `SET DATA TYPE` keywords
+        had_set: bool,
     },
+
     /// `ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( sequence_options ) ]`
     ///
     /// Note: this is a PostgreSQL-specific operation.
@@ -914,12 +917,19 @@ impl fmt::Display for AlterColumnOperation {
             AlterColumnOperation::DropDefault => {
                 write!(f, "DROP DEFAULT")
             }
-            AlterColumnOperation::SetDataType { data_type, using } => {
+            AlterColumnOperation::SetDataType {
+                data_type,
+                using,
+                had_set,
+            } => {
+                if *had_set {
+                    write!(f, "SET DATA ")?;
+                }
+                write!(f, "TYPE {data_type}")?;
                 if let Some(expr) = using {
-                    write!(f, "SET DATA TYPE {data_type} USING {expr}")
-                } else {
-                    write!(f, "SET DATA TYPE {data_type}")
+                    write!(f, " USING {expr}")?;
                 }
+                Ok(())
             }
             AlterColumnOperation::AddGenerated {
                 generated_as,

src/ast/spans.rs

@@ -924,6 +924,7 @@ impl Spanned for AlterColumnOperation {
             AlterColumnOperation::SetDataType {
                 data_type: _,
                 using,
+                had_set: _,
             } => using.as_ref().map_or(Span::empty(), |u| u.span()),
             AlterColumnOperation::AddGenerated { .. } => Span::empty(),
         }

src/dialect/mod.rs

@@ -1060,6 +1060,15 @@ pub trait Dialect: Debug + Any {
     fn supports_space_separated_column_options(&self) -> bool {
         false
     }
+
+    /// Returns true if the dialect supports the `USING` clause in an `ALTER COLUMN` statement.
+    /// Example:
+    ///  ```sql
+    ///  ALTER TABLE tbl ALTER COLUMN col SET DATA TYPE <type> USING <exp>`
+    /// ```
+    fn supports_alter_column_type_using(&self) -> bool {
+        false
+    }
 }
 
 /// This represents the operators for which precedence must be defined

src/dialect/postgresql.rs

@@ -258,4 +258,8 @@ impl Dialect for PostgreSqlDialect {
     fn supports_set_names(&self) -> bool {
         true
     }
+
+    fn supports_alter_column_type_using(&self) -> bool {
+        true
+    }
 }

src/parser/mod.rs

@@ -8734,16 +8734,10 @@ impl<'a> Parser<'a> {
                 }
             } else if self.parse_keywords(&[Keyword::DROP, Keyword::DEFAULT]) {
                 AlterColumnOperation::DropDefault {}
-            } else if self.parse_keywords(&[Keyword::SET, Keyword::DATA, Keyword::TYPE])
-                || (is_postgresql && self.parse_keyword(Keyword::TYPE))
-            {
-                let data_type = self.parse_data_type()?;
-                let using = if is_postgresql && self.parse_keyword(Keyword::USING) {
-                    Some(self.parse_expr()?)
-                } else {
-                    None
-                };
-                AlterColumnOperation::SetDataType { data_type, using }
+            } else if self.parse_keywords(&[Keyword::SET, Keyword::DATA, Keyword::TYPE]) {
+                self.parse_set_data_type(true)?
+            } else if self.parse_keyword(Keyword::TYPE) {
+                self.parse_set_data_type(false)?
             } else if self.parse_keywords(&[Keyword::ADD, Keyword::GENERATED]) {
                 let generated_as = if self.parse_keyword(Keyword::ALWAYS) {
                     Some(GeneratedAs::Always)
@@ -8909,6 +8903,22 @@ impl<'a> Parser<'a> {
         Ok(operation)
     }
 
+    fn parse_set_data_type(&mut self, had_set: bool) -> Result<AlterColumnOperation, ParserError> {
+        let data_type = self.parse_data_type()?;
+        let using = if self.dialect.supports_alter_column_type_using()
+            && self.parse_keyword(Keyword::USING)
+        {
+            Some(self.parse_expr()?)
+        } else {
+            None
+        };
+        Ok(AlterColumnOperation::SetDataType {
+            data_type,
+            using,
+            had_set,
+        })
+    }
+
     fn parse_part_or_partition(&mut self) -> Result<Partition, ParserError> {
         let keyword = self.expect_one_of_keywords(&[Keyword::PART, Keyword::PARTITION])?;
         match keyword {

tests/sqlparser_common.rs

@@ -5057,22 +5057,21 @@ fn parse_alter_table_alter_column_type() {
                 AlterColumnOperation::SetDataType {
                     data_type: DataType::Text,
                     using: None,
+                    had_set: true,
                 }
             );
         }
         _ => unreachable!(),
     }
+    verified_stmt(&format!("{alter_stmt} ALTER COLUMN is_active TYPE TEXT"));
 
-    let dialect = TestedDialects::new(vec![Box::new(GenericDialect {})]);
-
-    let res =
-        dialect.parse_sql_statements(&format!("{alter_stmt} ALTER COLUMN is_active TYPE TEXT"));
-    assert_eq!(
-        ParserError::ParserError("Expected: SET/DROP NOT NULL, SET DEFAULT, or SET DATA TYPE after ALTER COLUMN, found: TYPE".to_string()),
-        res.unwrap_err()
-    );
+    let dialects = all_dialects_where(|d| d.supports_alter_column_type_using());
+    dialects.verified_stmt(&format!(
+        "{alter_stmt} ALTER COLUMN is_active SET DATA TYPE TEXT USING 'text'"
+    ));
 
-    let res = dialect.parse_sql_statements(&format!(
+    let dialects = all_dialects_except(|d| d.supports_alter_column_type_using());
+    let res = dialects.parse_sql_statements(&format!(
         "{alter_stmt} ALTER COLUMN is_active SET DATA TYPE TEXT USING 'text'"
     ));
     assert_eq!(

tests/sqlparser_postgres.rs

@@ -764,10 +764,7 @@ fn parse_drop_extension() {
 
 #[test]
 fn parse_alter_table_alter_column() {
-    pg().one_statement_parses_to(
-        "ALTER TABLE tab ALTER COLUMN is_active TYPE TEXT USING 'text'",
-        "ALTER TABLE tab ALTER COLUMN is_active SET DATA TYPE TEXT USING 'text'",
-    );
+    pg().verified_stmt("ALTER TABLE tab ALTER COLUMN is_active TYPE TEXT USING 'text'");
 
     match alter_table_op(
         pg().verified_stmt(
@@ -783,6 +780,7 @@ fn parse_alter_table_alter_column() {
                 AlterColumnOperation::SetDataType {
                     data_type: DataType::Text,
                     using: Some(using_expr),
+                    had_set: true,
                 }
             );
         }