SQLite Forum

Explanation about C code style
> Is the sqlite3_release_memory() function the public API interface?

If you can find documentation for it in the public interface then yes, else no.

> What about sqlite3PcacheReleaseMemory()

The functions and data types with sqlite3CamelCaseNames are all internal, not for client-side use. They may be modified or removed by the sqlite3 developers at any time with no concerns for backwards compatibility (in strong contrast to the documented public APIs, which have strong backwards compatibility guarantees).