Which parameter would you typically use to define a persistent derived table?

Which parameter would you typically use to define a persistent derived table?

• A. is_persistent
• B. sql_trigger_value
• C. persist_for
• D. persisted

Answer: (C)

The parameter used to define a persistent derived table is "persist_for". This parameter specifies how long the derived table should remain in the cache after it has been populated. By leveraging this setting, developers can optimize performance by reducing the number of times the same data needs to be computed. Once the derived table is built, it will remain valid for the duration specified by "persist_for", thus providing efficiency in query execution by avoiding redundant computations. It is essential for maintaining up-to-date data while balancing performance needs, as it allows for controlling the trade-off between data freshness and query speed. The other options reflect different aspects of derived tables. "is_persistent" usually refers to a boolean setting that indicates whether a table is persistent but does not specify duration. "sql_trigger_value" is used to define conditions under which the derived table should be rebuilt, rather than how long it persists. "persisted" may imply a state but isn't an actual parameter used in LookML to define persistence duration.

The parameter used to define a persistent derived table is "persist_for". This parameter specifies how long the derived table should remain in the cache after it has been populated. By leveraging this setting, developers can optimize performance by reducing the number of times the same data needs to be computed.

Once the derived table is built, it will remain valid for the duration specified by "persist_for", thus providing efficiency in query execution by avoiding redundant computations. It is essential for maintaining up-to-date data while balancing performance needs, as it allows for controlling the trade-off between data freshness and query speed.

The other options reflect different aspects of derived tables. "is_persistent" usually refers to a boolean setting that indicates whether a table is persistent but does not specify duration. "sql_trigger_value" is used to define conditions under which the derived table should be rebuilt, rather than how long it persists. "persisted" may imply a state but isn't an actual parameter used in LookML to define persistence duration.