The server has a setParameter called internalQueryCacheSize which controls the maximum number of plan cache entries allowed in a single collection's plan cache. The parameter is poorly named, since it is not clear from the name whether the size is measured in number of entries or some other unit, such as bytes. It's also not clear that this is a maximum. And it's not clear whether the limit applies globally across all plan caches or whether the limit is per-collection.

In order to clarify some of these questions, we should rename internalQueryCacheSize to internalQueryCacheMaxEntriesPerCollection. This will also help avoid confusion after related ticket SERVER-40361 is implemented, since SERVER-40361 will introduce a separate plan cache size-related parameter called internalQueryCacheMaxSizeBytesBeforeStripDebugInfo. The rename proposed here will make sure that the two different plan cache size parameters cannot be easily confused with one another.

In order to avoid a breaking change for any user that has configured internalQueryCacheSize in a config file or on the command line, we continue to allow internalQueryCacheSize as a deprecated alias for{{internalQueryCacheMaxSizeBytesBeforeStripDebugInfo}}.