Ashttps://www.sqlite.org/wal.html mentioned, Specialized applications for which the default implementation of shared memory is unacceptable can devise alternative methods via a customVFS. For example, if it is known that a particular database will only be accessed by threads within a single process, the wal-index can be implemented using heap memory instead of true shared memory.
I may customize my ownxShmMap, xShmLock, xShmBarrier, and xShmUnmap methods to implement thewal-index using heap memory. And all these methods are in sqlite3_io_methods struct, BUT is there any C interface to set up those?