private String readOutAgentId(Buffer buffer) {
        String outAgentId = buffer.readPrefixedString();
        if (MERGE_AGENT.equals(outAgentId)) {
            // for gc
            return MERGE_AGENT;
        }
        return outAgentId;
    }
rowkey = caller col = callee

@author netspider
web/src/main/java/com/navercorp/pinpoint/web/applicationmap/dao/mapper/OutLinkMapper.java