fix(mysql): retry StarRocks cast errors during connection setup

crates/dbx-drivers/src/db/mysql.rs

@@ -1489,6 +1489,11 @@ fn mysql_group_concat_setup_fallback_mode(setup_mode: MySqlSetupMode, error: &st
         && compact.contains(&format!(
             "strconv.parseint:parsing\"cast(greatest(@@session.group_concat_max_len,{MYSQL_GROUP_CONCAT_MAX_LEN})asunsigned)\":invalidsyntax"
         ));
+    // StarRocks 3.1 can fail expression folding without echoing the SET statement.
+    let starrocks_setup_expression_rejected = lower.contains("error 1064 (hy000)")
+        && lower.contains(
+            "class com.starrocks.analysis.castexpr cannot be cast to class com.starrocks.analysis.literalexpr",
+        );
     // SphinxQL / Manticore reject the built-in `group_concat_max_len` setup with a
     // boolean-typed 1064 error. The quoted token after `near` depends on the exact
     // statement text, so accept any boolean rejection from SphinxQL that mentions
@@ -1507,6 +1512,7 @@ fn mysql_group_concat_setup_fallback_mode(setup_mode: MySqlSetupMode, error: &st
         || compact.contains(&format!("..._len,{MYSQL_GROUP_CONCAT_MAX_LEN})asunsigned)"));
     if (floor_statement_rejected && (setup_query_rejected || setup_value_rejected))
         || gaea_setup_expression_rejected
+        || starrocks_setup_expression_rejected
         || sphinxql_setup_query_rejected
         || gateway_session_variable_rejected
     {
@@ -8412,6 +8418,31 @@ mod tests {
         }
     }
 
+    #[test]
+    fn mysql_group_concat_starrocks_cast_error_retries_without_session_variable() {
+        let error = "MySQL connection failed: Server error: `ERROR 1064 (HY000): class com.starrocks.analysis.CastExpr cannot be cast to class com.starrocks.analysis.LiteralExpr (com.starrocks.analysis.CastExpr and com.starrocks.analysis.LiteralExpr are in unnamed module of loader 'app')'";
+
+        assert_eq!(
+            mysql_group_concat_setup_fallback_mode(MySqlSetupMode::Standard, error),
+            Some(MySqlSetupMode::Compatible)
+        );
+        assert_eq!(mysql_group_concat_setup_fallback_mode(MySqlSetupMode::Compatible, error), None);
+    }
+
+    #[test]
+    fn mysql_group_concat_starrocks_cast_retry_requires_exact_error() {
+        for error in [
+            "Server error: `ERROR 1105 (HY000): class com.starrocks.analysis.CastExpr cannot be cast to class com.starrocks.analysis.LiteralExpr'",
+            "Server error: `ERROR 1064 (42000): class com.starrocks.analysis.CastExpr cannot be cast to class com.starrocks.analysis.LiteralExpr'",
+            "Server error: `ERROR 1064 (HY000): class com.starrocks.analysis.SlotRef cannot be cast to class com.starrocks.analysis.LiteralExpr'",
+            "Server error: `ERROR 1064 (HY000): class com.starrocks.analysis.CastExpr cannot be cast to class com.starrocks.analysis.SlotRef'",
+            "Server error: `ERROR 1064 (HY000): class com.example.CastExpr cannot be cast to class com.example.LiteralExpr'",
+            "Server error: `ERROR 1064 (HY000): You have an error in your SQL syntax'",
+        ] {
+            assert_eq!(mysql_group_concat_setup_fallback_mode(MySqlSetupMode::Standard, error), None, "{error}");
+        }
+    }
+
     #[test]
     fn mysql_gateway_forbidden_global_variables_error_retries_without_session_variable() {
         let error = "MySQL connection failed: Server error: `ERROR 10192 (HY000): SET GLOBAL VARIABLES is forbidden'";

crates/dbx-drivers/tests/live_starrocks_setup_compatibility.rs

@@ -0,0 +1,56 @@
+use dbx_drivers::db::mysql;
+use mysql_async::prelude::Queryable;
+use std::time::Duration;
+
+#[tokio::test]
+#[ignore = "requires DBX_LIVE_STARROCKS_URL for a remote StarRocks with the SET CastExpr failure"]
+async fn live_starrocks_group_concat_setup_fallback() {
+    let url = std::env::var("DBX_LIVE_STARROCKS_URL").expect("DBX_LIVE_STARROCKS_URL");
+    let timeout = Duration::from_secs(15);
+    let bare_pool = mysql::connect_bare(&url, timeout).await.expect("bare StarRocks connection");
+    let mut bare_connection = bare_pool.get_conn().await.unwrap();
+    let version: Option<String> = bare_connection.query_first("SELECT current_version()").await.unwrap();
+    println!("StarRocks version: {version:?}");
+    let error = bare_connection
+        .query_drop(
+            "SET SESSION group_concat_max_len = \
+             cast(greatest(@@session.group_concat_max_len, 1048576) as unsigned)",
+        )
+        .await
+        .expect_err("server must reproduce the reported initialization failure")
+        .to_string();
+    println!("Rejected built-in setup: {error}");
+    assert!(error.contains("ERROR 1064 (HY000)"), "{error}");
+    assert!(
+        error.contains(
+            "class com.starrocks.analysis.CastExpr cannot be cast to class com.starrocks.analysis.LiteralExpr"
+        ),
+        "{error}"
+    );
+    drop(bare_connection);
+    bare_pool.disconnect().await.unwrap();
+
+    let extra_setup = ["SET query_timeout = 42".to_string()];
+    let pool = mysql::connect_with_ca_cert_pool_limit_idle_and_setup(&url, None, timeout, 2, None, &extra_setup)
+        .await
+        .expect("normal DBX connection must retry without its optional GROUP_CONCAT setup");
+    let mut first_connection = pool.get_conn().await.unwrap();
+    let mut second_connection = pool.get_conn().await.unwrap();
+    for connection in [&mut first_connection, &mut second_connection] {
+        let configured_timeout: Option<u64> = connection.query_first("SELECT @@query_timeout").await.unwrap();
+        assert_eq!(configured_timeout, Some(42));
+        let result: Option<u64> = connection.query_first("SELECT 1").await.unwrap();
+        assert_eq!(result, Some(1));
+        connection.query_drop("SHOW DATABASES").await.unwrap();
+    }
+    drop(first_connection);
+    drop(second_connection);
+    pool.disconnect().await.unwrap();
+
+    let invalid_setup = ["SET dbx_nonexistent_setup_variable = 1".to_string()];
+    let error = mysql::connect_with_ca_cert_pool_limit_idle_and_setup(&url, None, timeout, 2, None, &invalid_setup)
+        .await
+        .err()
+        .expect("invalid user setup must not be swallowed by the compatibility retry");
+    assert!(error.contains("dbx_nonexistent_setup_variable"), "{error}");
+}