Practice Test 4 | Google Cloud Certified Professional Data Engineer | Dumps | Mock Test
You work in banking related organization where data is stored in Google Cloud Spanner. Data schema is already designed in spanner. One of the bank divisions need to use this data in a heavily manner and would query few of the tables based on certain fixed columns which are not primary key for the table. The division is facing slowness while getting query result. Which of the statement is true and will solve the problem in cost effective manner?
A. Adding additional nodes to Cloud Spanner will provide more CPU and RAM. Thus query latency will be reduced.
B. Adding secondary index for the columns that are frequently queried will avoid full table scan and thus query latency will be reduced.
C. User can only add indexes at the time of table creation. Creating secondary index to an existing table while the database continue to serve traffic is not yet available.
D. At the time of table creation all the column which are defined as primary key is already indexed by Cloud Spanner. There is no concept of secondary index in Cloud Spanner. Creating another table will required columns and indexes will solve the problem.
Correct answer is B.
Refer GCP documentation https://cloud.google.com/spanner/docs/secondary-indexes#query-with-index
Option A is incorrect. Adding additional nodes will add more cost to the solution. Also, without correct indexes on the columns full table scan will be done. Adding nodes will not help to solve full table scan problem.
Option B is correct. We can add secondary index at the time of table creation and also for an existing table while the database continues to serve traffic. Adding secondary index will make that column more efficient and data look up in that column will be much faster. It will also avoid full table scan.
Option C is incorrect. User can add secondary table to an existing table without bringing the database down.
Option D is incorrect. User can create secondary index in cloud spanner. There is no need of creating another table or adding nodes to Cloud Spanner.
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