A table is registered with the following code: Both users and orders are Delta Lake tables. Which statement describes the results of querying recent_orders?
A.
All logic will execute at query time and return the result of joining the valid versions of the source tables at the time the query finishes.
B.
All logic will execute when the table is defined and store the result of joining tables to the DBFS; this stored data will be returned when the table is queried.
C.
Results will be computed and cached when the table is defined; these cached results will incrementally update as new records are inserted into source tables.
D.
All logic will execute at query time and return the result of joining the valid versions of the source tables at the time the query began.
E.
The versions of each source table will be stored in the table transaction log; query results will be saved to DBFS with each query.
The question says "Which statement describes the results of querying recent_orders?"
The question doesn't ask about the code snipped itself. This question is about the logic of "select * from recent_orders" after the creation of recent_orders.
answer is D
D is the right answer
Not sure how so many people misunderstood the actual question. It already says at the top that the table is registered as the code given, they're not executing the code again.
As Benni_ale said - CTAS can be used to create a snapshot of a table. The data will be stored and not updated further, unless table is explicitly updated.
option D mentions "return the result of joining the valid versions of the source tables" but that's not true. when u interrogate the table resulting from a join of two tables u are not re-performing joins operations at query time anymore an the version is the one from the last time the CTAS statement was executed
B - it is a table.
Query time answers assume we are talking about a view, which we aren't. Table is not automatically updated whenever the tables used in CTAS change - it is a standalone entity.
Only logic there is inside create statemetn and it will execute once while executing "create table" statement. Further select queries will only select any data that was inserted during create table statement , data wont by updated automatically. So B
B. All logic will execute when the table is defined and store the result of joining tables to the DBFS; this stored data will be returned when the table is queried.
The correct answer is:
B. All logic will execute when the table is defined and store the result of joining tables to the DBFS; this stored data will be returned when the table is queried.
When the CREATE TABLE AS statement is executed, it runs the enclosed SELECT statement immediately to pull the current data from the users and orders tables where the order_date is within the last 7 days. This result is then stored as a new table called recent_orders in the Delta Lake on the DBFS (Databricks File System). Subsequent queries against recent_orders will return this stored data, and not recompute the join unless the table is updated or refreshed.
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