True or False: The max_cache_age parameter causes PDTs to rebuild.

• A. True
• B. False
• C. Conditionally true
• D. Not applicable

Answer: (B)

The max_cache_age parameter does not directly cause Persistent Derived Tables (PDTs) to rebuild. Instead, it is used to define the maximum age of cached results before they are considered stale. When a PDT is executed, if the cached results are still valid within the max_cache_age timeframe, the existing results are returned, and there is no need for a rebuild. If the cached results exceed the specified max_cache_age, then Looker will determine that a rebuild is necessary and will execute the underlying query to refresh the data.

Understanding this distinction is crucial, as it highlights the role of max_cache_age in managing the freshness of data in PDTs without directly triggering their creation or rebuilding processes. This means that while the parameter can affect when a PDT is rebuilt based on the age of the cached data, the primary function is about cache management rather than an action that initiates a rebuild.