You work for a large ecommerce company.

By using a timestamp range filter in the query, you can ensure that the analysts only see the customer data that is withinthe desired time range, regardless of the garbage collection policy1. This option is the most cost-effective and simple way to avoid fetching data that is marked for deletion by garbage collection, as it does not require changing the existing policy or creating additional jobs. You can use the Bigtable client libraries or the cbt CLI to apply atimestamp range filter to your read requests2.

Option A is not effective, as it increases the number of versions to 2, which may cause more data to be retained and increase the storage costs. Option C is not reliable, as it reduces the expiring values to 29 days, which may not match the actual data arrival and usage patterns. Option D is not efficient, as it requires scheduling a job daily to scan and delete the data, which may incur additional overhead and complexity. Moreover, none of these options guarantee that the data older than 30 days will be immediately deleted, as garbage collection isan asynchronous process that can take up to a week to remove the data3. References:

1: Filters | Cloud Bigtable Documentation | Google Cloud

2: Read data | Cloud Bigtable Documentation | Google Cloud

3: Garbage collection overview | Cloud Bigtable Documentation | Google Cloud