Hi Rowan. Thanks for the pointer to immutable mode, but can I just elaborate my expectations. The 1.6 GB read-only database may be read by 10 processes simultaneously. What I'm looking for is for Linux to fully cache that file in memory, but with just one copy of it. It's not something for Sqlite to do, although maybe fsync() interferes with Linux's ability to do this? The solution of copying the file to /dev/shm will work, and so will an ordinary local disk. But that means a more difficult deployment instead of just sticking the file on a network drive for everyone to use. If you think that immutable mode might solve this problem, I can suggest it.