public String buildCacheKey(Map<String, Object> refData) {
        StringBuilder keyBuilder = new StringBuilder(tableName);
        for (String primaryKey : primaryKeys) {
            if (!refData.containsKey(primaryKey)) {
                return null;
            }
            keyBuilder.append("_").append(refData.get(primaryKey));
        }
        return keyBuilder.toString();
    }
1. build key from map.
 2. save key and value.
 3. set expired time for key when keyExpiredTime has been set.
@param refData
redis5/redis5-sink/src/main/java/com/dtstack/flink/sql/sink/redis/RedisOutputFormat.java