Performance Optimization Flashcards

In slim CI, which selector builds only modified models and everything downstream of them?

Answer: state:modified+

state:modified+ compares against a prior manifest and includes modified nodes plus their descendants.

What does --defer do when running a subset of models in CI?

Answer: Resolves refs to unselected models using the production state artifacts

--defer with --state points unbuilt upstream refs at the production relations so you need not rebuild them.

Which command can create zero-copy clones of production relations in a dev schema on supporting warehouses?

Answer: dbt clone

dbt clone uses the warehouse's native cloning to quickly replicate nodes from a state manifest.

What does incremental_predicates add to an incremental merge or delete+insert?

Answer: Additional SQL conditions on the target table to limit the scan during the merge

incremental_predicates restrict the destination rows examined, reducing scan cost on large tables.

Why might a view-materialized model chain become slow?

Answer: Each downstream query re-executes all upstream view logic at query time

Views store only a query, so stacked views are recomputed on every read, which can be expensive.

Which flag stops the dbt invocation immediately upon the first model failure?

Answer: --fail-fast

--fail-fast (-x) aborts execution as soon as one node fails, saving compute and time.

What is a common reason to choose the table materialization over view?

Answer: Faster reads when the model is queried often and is expensive to compute

Tables precompute results so repeated downstream queries are quicker at the cost of storage and build time.