I'm exploring what it would take to support more than 10 attached databases within one SQLite connection object. It appears that the change will be rather simple:
ATTACH_MAX can be made as high as 30 without further issues, given the writeMask and cookieMask field's bit width being 32 bits, with two bits reserved for the main and temporary data stores. If I wanted to increase ATTACH_MAX even farther, going up through 62 would be relatively easy, assuming 64-bit support in the compiler (as determined by sqlite_uint64), changing the datatypes for writeMask and cookieMask in structure Parse, and verifying the mask computations continue to work, and running all the tests on the desired platforms. Statements like "1<<iDb" might need to be changed to read "1ULL << iDb" (1 unsigned long long) for some sorts of excessive warnings, although I haven't yet checked. Are there any other issues known by changing ATTACH_MAX to a number like 62? I imagine that the Parse structure size changing might be an issue for pre-parsed statements... The code for attaching databases (attachFunc()) appears to be agnostic when it comes to these limits.
