title: Trying to simulate cell level TTL in bigtable but whole column family data is getting removed by garbage collection
body: <p>created a table with the following rules:
  so with this, data should expire after 1 second (<a href="https://cloud.google.com/bigtable/docs/gc-cell-level" rel="noreferrer">as per docs</a>)</p>
  
  <pre><code>async function createTable() {
      console.log("Creating Table");
      const options = {
          families: [
              {
                  name: 'payloads',
                  rule: {
                      age: {
                          seconds: 1,
                          nanos: 0,
                      },
                  },
              },
          ],
      };
      try {
          await table.create(options);
          console.log("Successfully Created Table");
      } catch (err) {
          console.error(`Error reading rows :`, err);
      }
  }
  </code></pre>
  
  <p>And then inserted the data like this: </p>
  
  <pre><code>      const rowsToInsert = {
              key: "SUMEET",
              data: {
                  payloads: {
                      '1': {
                          value: "NOTIFICATIONS_PAYLOAD_1",
                          timestamp: 1576500927000,
                      },
                      '2': {
                          value: "NOTIFICATIONS_PAYLOAD_2",
                          timestamp: 1576587327000,
                      },
                      '3': {
                          value: "NOTIFICATIONS_PAYLOAD_3",
                          timestamp: 1576673727000,
                      },
                      '4': {
                          value: "NOTIFICATIONS_PAYLOAD_4",
                          timestamp: 1576760127000,
                      },
                  },
              },
          };
  
          await table.insert(rowsToInsert);
  </code></pre>
  
  <p>so i added four cells with different timeStamp:</p>
  
  <ol>
  <li>First with 5 minutes ahead of time when am writing the data</li>
  <li>Second with 1 hour ahead</li>
  <li>third with 1 day ahead</li>
  <li>fourth with 2 day ahead</li>
  </ol>
  
  <p>problem here is when m reading the data whole column family data is getting deleted but it should delete only first and second cell only as per the rules set</p>
  
  <p>Is there anything am missing or am doing wrong ??</p>