CERTIFIED-DATA-ENGINEER-PROFESSIONAL · Question #63
A Databricks SQL dashboard has been configured to monitor the total number of records present in a collection of Delta Lake tables using the following query pattern: SELECT COUNT (*) FROM table…
The correct answer is C. The total count of records is calculated from the Delta transaction logs. Delta Lake maintains a transaction log that records details about every change made to a table. When you execute a count operation on a Delta table, Delta Lake can use the information in the transaction log to calculate the total number of records without having to scan all the…
Question
A Databricks SQL dashboard has been configured to monitor the total number of records present in a collection of Delta Lake tables using the following query pattern:
SELECT COUNT (*) FROM table Which of the following describes how results are generated each time the dashboard is updated?
Options
- AThe total count of rows is calculated by scanning all data files
- BThe total count of rows will be returned from cached results unless REFRESH is run
- CThe total count of records is calculated from the Delta transaction logs
- DThe total count of records is calculated from the parquet file metadata
- EThe total count of records is calculated from the Hive metastore
How the community answered
(49 responses)- A2% (1)
- B4% (2)
- C88% (43)
- D6% (3)
Explanation
Delta Lake maintains a transaction log that records details about every change made to a table. When you execute a count operation on a Delta table, Delta Lake can use the information in the transaction log to calculate the total number of records without having to scan all the data files. This is because the transaction log includes information about the number of records in each file, allowing for an efficient aggregation of these counts to get the total number of records in the
Topics
Community Discussion
No community discussion yet for this question.