title: Prometheus metrics with timestamp
body: <p>When I query metrics from prometheus, I just get the timestamp when I queried. </p>
  
  <p>For example, If I query data like this, </p>
  
  <p><code>http://localhost:9090/api/v1/query?query=go_memstats_buck_hash_sys_bytes</code></p>
  
  <p>Then I got the response like following. </p>
  
  <pre><code>{
      "status": "success",
      "data": {
          "resultType": "vector",
          "result": [
              {
                  "metric": {
                      "__name__": "go_memstats_buck_hash_sys_bytes",
                      "instance": "localhost:9090",
                      "job": "prometheus"
                  },
                  "value": [
                      1557366670.588, &lt;== UNIX time stamp when I queried.
                      "1472884" &lt;== Value
                  ]
              }
          ]
      }
  }
  </code></pre>
  
  <p>But in the graph view, I can see the graph like following. It means I can query data with timestamp that prometheus. </p>
  
  <p><a href="https://i.stack.imgur.com/t5ppC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/t5ppC.png" alt="enter image description here"></a></p>
  
  <p>I wanna know how to query metrics with timestamp that prometheus has. </p>