MySQL-CDC diagnostic: failed to query MySQL server identity:

Error message

MySQL-CDC diagnostic: failed to query MySQL server identity: {}

What it means

Diagnostic WARN from logMySqlServerIdentity's catch block: the SQL query used to fetch server identity (server_id, uuid, gtid_mode, etc.) raised a SQLException, so the identity diagnostics could not be collected. The CDC task itself continues; only the diagnostic output is lost.

Source

Thrown at seatunnel-connectors-v2/connector-cdc/connector-cdc-mysql/src/main/java/org/apache/seatunnel/connectors/seatunnel/cdc/mysql/source/reader/fetch/MySqlSourceFetchTaskContext.java:477

            connection.query(
                    sql,
                    rs -> {
                        if (!rs.next()) {
                            return;
                        }
                        LOG.warn(
                                "MySQL-CDC diagnostic: connected to MySQL hostname={}, port={}, server_id={}, server_uuid={}, read_only={}, super_read_only={}, version={}, gtid_mode={}",
                                rs.getString("hostname"),
                                rs.getString("port"),
                                rs.getString("server_id"),
                                rs.getString("server_uuid"),
                                rs.getString("read_only"),
                                rs.getString("super_read_only"),
                                rs.getString("version"),
                                rs.getString("gtid_mode"));
                    });
        } catch (SQLException e) {
            LOG.warn(
                    "MySQL-CDC diagnostic: failed to query MySQL server identity: {}",
                    e.getMessage());
        }
    }

    private void logMySqlBinlogRetentionVariables() {
        logMySqlVariable("log_bin");
        logMySqlVariable("binlog_format");
        logMySqlVariable("binlog_expire_logs_seconds");
        logMySqlVariable("expire_logs_days");
    }

    private void logMySqlVariable(String variableName) {
        final String sql = String.format("SHOW VARIABLES LIKE '%s'", variableName);
        try {
            connection.query(
                    sql,
                    rs -> {

View on GitHub (pinned to cf67b549a7)

Solutions

Grant the CDC user privileges to query system variables/information_schema (e.g. SELECT on *.* or PERFORMANCE_SCHEMA/session_variables)
Check network stability to the MySQL host; re-run the job and inspect earlier connection errors
If a proxy restricts queries, run the identity SQL manually with a DBA account to gather the same values

Example fix

// before
GRANT SELECT ON db.* TO 'stuser'@'%';
// after
GRANT SELECT, RELOAD, REPLICATION CLIENT, REPLICATION SLAVE ON *.* TO 'stuser'@'%';

Defensive patterns

Strategy: try-catch

Validate before calling

// Verify privileges and connectivity first
mysql -h <host> -u stuser -p -e 'SELECT @@gtid_mode; SELECT @@server_uuid;'
SHOW GRANTS FOR 'stuser'@'%';

Try / catch

try {
    runIdentityQuery(connection);
} catch (SQLException e) {
    LOG.warn("identity diagnostics skipped: {}", e.getMessage());
    // fall back to manual SHOW VARIABLES as DBA
}

Prevention

Grant SELECT on information_schema/PERFORMANCE_SCHEMA and global variable read access to the CDC user
Keep connections alive across the diagnostic phase (avoid pool teardown mid-task)
Whitelist SHOW/SELECT diagnostics on DB proxies

When it happens

Trigger: The identity query fails due to lost connection, insufficient privileges to read the queried variables/information_schema, or the server rejecting the diagnostic SQL while handling a binlog/GTID unavailability condition.

Common situations: User lacks SELECT privilege on information_schema or SESSION_VARIABLES; connection dropped mid-diagnostic; firewall or proxy blocking the query.

Understand the failure class

Background: "query failed", "%w: SQL error" — wrapped database query errors in Go libraries explained — this error's family across 3 libraries.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/5613de116075c18a. Report an issue: GitHub.