@Override
    public String getLimitClause(long limit) {
        return "LIMIT " + limit;
    }
copy from flink-jdbc
modify upsert statement implement
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/jdbc/src/main/java/org/apache/inlong/sort/jdbc/dialect/TDSQLPostgresDialect.java