Practice Test 3 | Google Cloud Certified Professional Data Engineer | Dumps | Mock Test

Correct Answer: A and C

There are several factors that can cause Cloud Bigtable to perform more slowly than expected:

• The table’s schema is not designed correctly. To get good performance from Cloud BigTable, it’s essential to design a schema that makes it possible to distribute reads and writes evenly across each table.
• The workload isn’t appropriate for Cloud BigTable. If you test with a small amount (< 300 GB) of data, or if you test for a very short period of time (seconds rather than minutes or hours), Cloud BigTable won’t be able to balance your data in a way that gives you good performance.
• The rows in your Cloud Bigtable contain large amounts of data. You can read and write a larger amount of data per row, but increasing the amount of data per row will also reduce the number of rows per second.
• The rows in your Cloud Bigtable contain a very large number of cells. It takes time for Cloud Bigtable to process each cell in a row. Also, each cell adds some overhead to the amount of data that’s stored in your table and sent over the network.
• The Cloud Bigtable cluster doesn’t have enough nodes. If your Cloud Bigtable cluster is overloaded, adding more nodes can improve the performance.
• The Cloud Bigtable cluster was scaled up or scaled down recently. After you change the number of nodes in a cluster, it can take up to 20 minutes under load before you see an improvement in the cluster’s performance.
• The Cloud Bigtable cluster uses HDD disks. In most cases, your cluster should use SSD disks, which have significantly better performance than HDD disks.
• The Cloud Bigtable instance is a development instance. The performance of a development instance is equivalent to an instance with one single-node cluster, it will not perform as well as a production instance.
• There are issues with the network connection. Network issues can reduce throughput and cause reads and writes to take longer than usual.

Reference:

• https://cloud.google.com/bigtable/docs/performance

Additional info:

The followings are supported logic:-

Option C: The instance doesn’t have enough nodes

There is enough scope for an increase in traffic and a No. of Nodes is not enough to cope with such a huge No. of traffic.

Option A: The rows in the tables have a large data size

This is also possible that “The rows in your Cloud Bigtable contain large amounts of data”

Option D: The instance uses SDD storage type

This is of course not possible for the slow performance.