sql: unparse array_has as ANY for Postgres

PostgreSQL does not have an array_has() function — it uses the
`= ANY(array)` operator for array containment checks. Without this
dialect override, SQL unparsed for Postgres federation produces
invalid syntax. This converts array_has(haystack, needle) to
needle = ANY(haystack) in the PostgreSqlDialect.

Author: vimeh

datafusion/sql/src/unparser/dialect.rs

@@ -351,6 +351,10 @@ impl Dialect for PostgreSqlDialect {
         func_name: &str,
         args: &[Expr],
     ) -> Result<Option<ast::Expr>> {
+        if func_name == "array_has" {
+            return self.array_has_to_sql_any(unparser, args);
+        }
+
         if func_name == "round" {
             return Ok(Some(
                 self.round_to_sql_enforce_numeric(unparser, func_name, args)?,
@@ -362,6 +366,23 @@ impl Dialect for PostgreSqlDialect {
 }
 
 impl PostgreSqlDialect {
+    fn array_has_to_sql_any(
+        &self,
+        unparser: &Unparser,
+        args: &[Expr],
+    ) -> Result<Option<ast::Expr>> {
+        let [haystack, needle] = args else {
+            return Ok(None);
+        };
+
+        Ok(Some(ast::Expr::AnyOp {
+            left: Box::new(unparser.expr_to_sql(needle)?),
+            compare_op: BinaryOperator::Eq,
+            right: Box::new(unparser.expr_to_sql(haystack)?),
+            is_some: false,
+        }))
+    }
+
     fn round_to_sql_enforce_numeric(
         &self,
         unparser: &Unparser,

datafusion/sql/src/unparser/expr.rs

@@ -1853,7 +1853,7 @@ mod tests {
     use datafusion_functions::expr_fn::{get_field, named_struct};
     use datafusion_functions_aggregate::count::count_udaf;
     use datafusion_functions_aggregate::expr_fn::sum;
-    use datafusion_functions_nested::expr_fn::{array_element, make_array};
+    use datafusion_functions_nested::expr_fn::{array_element, array_has, make_array};
     use datafusion_functions_nested::map::map;
     use datafusion_functions_window::rank::rank_udwf;
     use datafusion_functions_window::row_number::row_number_udwf;
@@ -3074,6 +3074,24 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn test_postgres_array_has_to_any() -> Result<()> {
+        let default_dialect: Arc<dyn Dialect> = Arc::new(DefaultDialect {});
+        let postgres_dialect: Arc<dyn Dialect> = Arc::new(PostgreSqlDialect {});
+        let expr = array_has(col("items"), lit(1));
+
+        for (dialect, expected) in [
+            (default_dialect, "array_has(\"items\", 1)"),
+            (postgres_dialect, "1 = ANY(\"items\")"),
+        ] {
+            let unparser = Unparser::new(dialect.as_ref());
+            let actual = format!("{}", unparser.expr_to_sql(&expr)?);
+            assert_eq!(actual, expected);
+        }
+
+        Ok(())
+    }
+
     #[test]
     fn test_window_func_support_window_frame() -> Result<()> {
         let default_dialect: Arc<dyn Dialect> =

datafusion/sql/tests/cases/plan_to_sql.rs

@@ -361,6 +361,17 @@ fn roundtrip_statement_with_dialect_3() -> Result<(), DataFusionError> {
     Ok(())
 }
 
+#[test]
+fn roundtrip_statement_postgres_any_array_expr() -> Result<(), DataFusionError> {
+    roundtrip_statement_with_dialect_helper!(
+        sql: "select left from array where 1 = any(left);",
+        parser_dialect: GenericDialect {},
+        unparser_dialect: UnparserPostgreSqlDialect {},
+        expected: @r#"SELECT "array"."left" FROM "array" WHERE 1 = ANY("array"."left")"#,
+    );
+    Ok(())
+}
+
 #[test]
 fn roundtrip_statement_with_dialect_4() -> Result<(), DataFusionError> {
     roundtrip_statement_with_dialect_helper!(