Note that a recent patch allows "memdb" databases to be shared by multiple connections (not shared-cache) in the same process. See <https://www.sqlite.org/src/info/533fffc4a39b01c3> Presumably this will, after testing, be included in the next release. To share a memory database across multiple processes, you need to put it in a shared-memory filesystem (ramdisk or /dev/shm for example).