Practice Test 1 | Google Cloud Certified Professional Data Engineer | Dumps | Mock Test
Your team decided to use BigTable for storing event data. The engineer responsible of launching and testing the instance has reported a slower performance than expected by Google Cloud documentation. Which of the following could be a factor for the slow performance? (Choose 3)
A. The rows in the tables tested contain high number of cells.
B. The rows in the tables have large data size.
C. Test data size is over 300GB.
D. The instance uses SSD storage type.
E. Heavy pre-test was done before the testing started.
F. The instance doesn’t have enough nodes.
Answers: A, B & F
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 table contain large amounts of data. You can read and write larger amounts 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 table 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 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. Development instance’s performance 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.
Source(s):
Understanding BigTable Performance: https://cloud.google.com/bigtable/docs/performance
Comments are closed, but trackbacks and pingbacks are open.