PostgreSQL: Parse ROWS FROM table functions

src/ast/query.rs

@@ -1513,6 +1513,15 @@ pub enum TableFactor {
         /// Optional alias for the table function result.
         alias: Option<TableAlias>,
     },
+    /// `ROWS FROM(function_call [, ...]) [WITH ORDINALITY][ AS <alias> ]`
+    RowsFrom {
+        /// Table functions combined by `ROWS FROM`.
+        table_functions: Vec<TableFactor>,
+        /// Whether `WITH ORDINALITY` was specified to include ordinality.
+        with_ordinality: bool,
+        /// Optional alias for the `ROWS FROM` result.
+        alias: Option<TableAlias>,
+    },
     /// `e.g. LATERAL FLATTEN(<args>)[ AS <alias> ]`
     Function {
         /// Whether the function is LATERAL.
@@ -2316,6 +2325,20 @@ impl fmt::Display for TableFactor {
                 }
                 Ok(())
             }
+            TableFactor::RowsFrom {
+                table_functions,
+                with_ordinality,
+                alias,
+            } => {
+                write!(f, "ROWS FROM({})", display_comma_separated(table_functions))?;
+                if *with_ordinality {
+                    write!(f, " WITH ORDINALITY")?;
+                }
+                if let Some(alias) = alias {
+                    write!(f, " {alias}")?;
+                }
+                Ok(())
+            }
             TableFactor::UNNEST {
                 alias,
                 array_exprs,

src/ast/spans.rs

@@ -2001,6 +2001,16 @@ impl Spanned for TableFactor {
             TableFactor::TableFunction { expr, alias } => expr
                 .span()
                 .union_opt(&alias.as_ref().map(|alias| alias.span())),
+            TableFactor::RowsFrom {
+                table_functions,
+                with_ordinality: _,
+                alias,
+            } => union_spans(
+                table_functions
+                    .iter()
+                    .map(|i| i.span())
+                    .chain(alias.as_ref().map(|alias| alias.span())),
+            ),
             TableFactor::UNNEST {
                 alias,
                 with_offset: _,

src/dialect/generic.rs

@@ -77,6 +77,10 @@ impl Dialect for GenericDialect {
         true
     }
 
+    fn supports_rows_from_table_factor(&self) -> bool {
+        true
+    }
+
     fn supports_start_transaction_modifier(&self) -> bool {
         true
     }

src/dialect/mod.rs

@@ -732,6 +732,13 @@ pub trait Dialect: Debug + Any {
         false
     }
 
+    /// Return true if the dialect supports `ROWS FROM` in table functions.
+    ///
+    /// See <https://www.postgresql.org/docs/current/queries-table-expressions.html#QUERIES-TABLEFUNCTIONS>
+    fn supports_rows_from_table_factor(&self) -> bool {
+        false
+    }
+
     /// Does the dialect support MySQL-style `'user'@'host'` grantee syntax?
     fn supports_user_host_grantee(&self) -> bool {
         false

src/dialect/postgresql.rs

@@ -255,6 +255,10 @@ impl Dialect for PostgreSqlDialect {
         true
     }
 
+    fn supports_rows_from_table_factor(&self) -> bool {
+        true
+    }
+
     /// See <https://www.postgresql.org/docs/current/functions-json.html>
     ///
     /// Required to support the colon in:

src/parser/mod.rs

@@ -16611,6 +16611,7 @@ impl<'a> Parser<'a> {
                         | TableFactor::XmlTable { alias, .. }
                         | TableFactor::OpenJsonTable { alias, .. }
                         | TableFactor::TableFunction { alias, .. }
+                        | TableFactor::RowsFrom { alias, .. }
                         | TableFactor::Pivot { alias, .. }
                         | TableFactor::Unpivot { alias, .. }
                         | TableFactor::MatchRecognize { alias, .. }
@@ -16678,42 +16679,23 @@ impl<'a> Parser<'a> {
                 alias,
                 sample: None,
             })
-        } else if dialect_of!(self is BigQueryDialect | PostgreSqlDialect | GenericDialect)
-            && self.parse_keyword(Keyword::UNNEST)
+        } else if self.dialect.supports_rows_from_table_factor()
+            && self.parse_keywords(&[Keyword::ROWS, Keyword::FROM])
         {
             self.expect_token(&Token::LParen)?;
-            let array_exprs = self.parse_comma_separated(Parser::parse_expr)?;
+            let table_functions = self.parse_comma_separated(Parser::parse_rows_from_function)?;
             self.expect_token(&Token::RParen)?;
-
             let with_ordinality = self.parse_keywords(&[Keyword::WITH, Keyword::ORDINALITY]);
-            let alias = match self.maybe_parse_table_alias() {
-                Ok(Some(alias)) => Some(alias),
-                Ok(None) => None,
-                Err(e) => return Err(e),
-            };
-
-            let with_offset = match self.expect_keywords(&[Keyword::WITH, Keyword::OFFSET]) {
-                Ok(()) => true,
-                Err(_) => false,
-            };
-
-            let with_offset_alias = if with_offset {
-                match self.parse_optional_alias(keywords::RESERVED_FOR_COLUMN_ALIAS) {
-                    Ok(Some(alias)) => Some(alias),
-                    Ok(None) => None,
-                    Err(e) => return Err(e),
-                }
-            } else {
-                None
-            };
-
-            Ok(TableFactor::UNNEST {
-                alias,
-                array_exprs,
-                with_offset,
-                with_offset_alias,
+            let alias = self.maybe_parse_table_alias()?;
+            Ok(TableFactor::RowsFrom {
+                table_functions,
                 with_ordinality,
+                alias,
             })
+        } else if dialect_of!(self is BigQueryDialect | PostgreSqlDialect | GenericDialect)
+            && self.parse_keyword(Keyword::UNNEST)
+        {
+            self.parse_unnest_table_factor()
         } else if self.dialect.supports_unpivot_expr() && self.peek_keyword(Keyword::UNPIVOT) {
             self.parse_unpivot_expr_table_factor()
         } else if self.parse_keyword_with_tokens(Keyword::JSON_TABLE, &[Token::LParen]) {
@@ -16841,6 +16823,67 @@ impl<'a> Parser<'a> {
         }
     }
 
+    fn parse_rows_from_function(&mut self) -> Result<TableFactor, ParserError> {
+        if self.parse_keyword(Keyword::UNNEST) {
+            return self.parse_unnest_table_factor();
+        }
+
+        let name = self.parse_object_name(true)?;
+        self.expect_token(&Token::LParen)?;
+        let args = Some(self.parse_table_function_args()?);
+        let with_ordinality = self.parse_keywords(&[Keyword::WITH, Keyword::ORDINALITY]);
+        let alias = self.maybe_parse_table_alias()?;
+
+        Ok(TableFactor::Table {
+            name,
+            alias,
+            args,
+            with_hints: vec![],
+            version: None,
+            partitions: vec![],
+            with_ordinality,
+            json_path: None,
+            sample: None,
+            index_hints: vec![],
+        })
+    }
+
+    fn parse_unnest_table_factor(&mut self) -> Result<TableFactor, ParserError> {
+        self.expect_token(&Token::LParen)?;
+        let array_exprs = self.parse_comma_separated(Parser::parse_expr)?;
+        self.expect_token(&Token::RParen)?;
+
+        let with_ordinality = self.parse_keywords(&[Keyword::WITH, Keyword::ORDINALITY]);
+        let alias = match self.maybe_parse_table_alias() {
+            Ok(Some(alias)) => Some(alias),
+            Ok(None) => None,
+            Err(e) => return Err(e),
+        };
+
+        let with_offset = match self.expect_keywords(&[Keyword::WITH, Keyword::OFFSET]) {
+            Ok(()) => true,
+            Err(_) => false,
+        };
+
+        let with_offset_alias = if with_offset {
+            match self.parse_optional_alias(keywords::RESERVED_FOR_COLUMN_ALIAS) {
+                Ok(Some(alias)) => Some(alias),
+                Ok(None) => None,
+                Err(e) => return Err(e),
+            }
+        } else {
+            None
+        };
+
+        Ok(TableFactor::UNNEST {
+            alias,
+            array_exprs,
+            with_offset,
+            with_offset_alias,
+            with_ordinality,
+        })
+    }
+
     /// Parse a Snowflake stage reference as a table factor.
     /// Handles syntax like: `@mystage1 (file_format => 'myformat', pattern => '...')`
     ///

tests/sqlparser_postgres.rs

@@ -9953,3 +9953,23 @@ fn parse_insert_by_name_keywords_as_table_and_alias() {
         statement => panic!("Expected INSERT statement, got: {statement:?}"),
     }
 }
+
+#[test]
+fn parse_rows_from_with_ordinality() {
+    pg_and_generic().verified_stmt(
+        "SELECT * FROM ROWS FROM(UNNEST(ARRAY[1, 2]) WITH ORDINALITY) AS r (val, ord)",
+    );
+
+    pg_and_generic().verified_stmt(
+        "SELECT * FROM ROWS FROM(UNNEST(ARRAY[1, 2])) WITH ORDINALITY AS r (val, ord)",
+    );
+
+    pg_and_generic().verified_stmt(
+        "SELECT * FROM ROWS FROM(UNNEST(ARRAY[1]), generate_series(1, 2)) AS r (a, b)",
+    );
+
+    let err = pg_and_generic()
+        .parse_sql_statements("SELECT * FROM ROWS FROM(foo)")
+        .unwrap_err();
+    assert_eq!("sql parser error: Expected: (, found: )", err.to_string());
+}