DBT Performance Optimization 2

Question 1

Which command re-runs only the nodes that failed or were skipped in the previous invocation?

Accepted Answer

dbt retry

Answer

dbt retry reads run_results.json from the last run and executes only failed or skipped nodes.

Question 2

What is the main purpose of the is_incremental() macro in an incremental model?

Accepted Answer

To return true only when the model already exists as a table and is not run with --full-refresh

Answer

is_incremental() lets you filter source rows only on subsequent runs, when the target table exists and no full refresh is requested.

Question 3

Which incremental strategy deletes matching rows by unique_key and then inserts the new rows, which can be faster than merge on some warehouses?

Accepted Answer

delete+insert

Answer

The delete+insert strategy removes rows matching unique_key and inserts fresh rows, avoiding the cost of a MERGE statement.

Question 4

How can you reduce the amount of data processed in development without changing production logic?

Accepted Answer

Use a target.name conditional to filter to recent data only in dev

Answer

Wrapping a date filter in an if target.name == 'dev' Jinja block limits dev data while prod runs the full dataset.

Question 5

Which artifact contains per-node execution timing that helps identify the slowest models?

Accepted Answer

run_results.json

Answer

run_results.json records execution_time and timing details for every node in the last invocation.

DBT - Certified Data Build Tool Developer Practice Test