fix(select): classify function argument planner errors

crates/s3select-query/src/sql/planner.rs

@@ -68,7 +68,7 @@ impl<'a, S: ContextProviderExtension + Send + Sync + 'a> SqlPlanner<'a, S> {
         match stmt {
             Statement::Query(_) => {
                 validate_s3_select_statement(&stmt)?;
-                let df_plan = self.df_planner.sql_statement_to_plan(stmt)?;
+                let df_plan = self.df_planner.sql_statement_to_plan(stmt).map_err(classify_planner_error)?;
                 let plan = Plan::Query(QueryPlan {
                     df_plan,
                     is_tag_scan: false,
@@ -81,6 +81,20 @@ impl<'a, S: ContextProviderExtension + Send + Sync + 'a> SqlPlanner<'a, S> {
     }
 }
 
+fn classify_planner_error(error: datafusion::common::DataFusionError) -> QueryError {
+    if matches!(
+        &error,
+        datafusion::common::DataFusionError::Plan(message)
+            if message.starts_with("Failed to coerce arguments to satisfy a call to")
+                || (message.starts_with("Internal error: Function '")
+                    && message.contains("' failed to match any signature, errors:"))
+    ) {
+        return SelectError::IncorrectSqlFunctionArgumentType.into();
+    }
+
+    error.into()
+}
+
 fn validate_s3_select_statement(statement: &Statement) -> QueryResult<()> {
     let Statement::Query(query) = statement else {
         return Err(unsupported_structure("only SELECT queries are supported"));

crates/s3select-query/src/test/error_handling_test.rs

@@ -127,6 +127,53 @@ mod error_handling_tests {
         assert!(matches!(error.select_error(), SelectError::UnsupportedSqlStructure { .. }));
     }
 
+    #[tokio::test]
+    async fn test_function_argument_coercion_failure_is_typed() {
+        for sql in ["SELECT ROUND(3.14, 1.1) FROM S3Object", "SELECT SQRT(1, 2) FROM S3Object"] {
+            let input = create_test_input_with_sql(sql);
+            let db = get_global_db(input.clone(), true)
+                .await
+                .expect("test database should initialize");
+            let query = Query::new(Context { input: Arc::new(input) }, sql.to_string());
+
+            let error = match db.execute(&query).await {
+                Err(error) => error,
+                Ok(_) => panic!("invalid function arguments must fail during planning: {sql}"),
+            };
+
+            assert_eq!(
+                error.select_error(),
+                SelectError::IncorrectSqlFunctionArgumentType,
+                "unexpected planner error for {sql}: {error:?}"
+            );
+        }
+    }
+
+    #[tokio::test]
+    async fn test_other_planner_failures_remain_invalid_query() {
+        for sql in [
+            "SELECT DEFINITELY_UNKNOWN_FUNCTION(1) FROM S3Object",
+            "SELECT 1 + 'text' FROM S3Object",
+        ] {
+            let input = create_test_input_with_sql(sql);
+            let db = get_global_db(input.clone(), true)
+                .await
+                .expect("test database should initialize");
+            let query = Query::new(Context { input: Arc::new(input) }, sql.to_string());
+
+            let error = match db.execute(&query).await {
+                Err(error) => error,
+                Ok(_) => panic!("invalid query must fail during planning: {sql}"),
+            };
+
+            assert_eq!(
+                error.select_error(),
+                SelectError::InvalidQuery,
+                "unexpected planner error for {sql}: {error:?}"
+            );
+        }
+    }
+
     #[tokio::test]
     async fn test_invalid_column_references() {
         let invalid_column_sqls = vec![