Thanks Richard. I'll do as you suggest for all indexes, UNIQUE or NOT. My PRIMARY KEYs are all either INTEGER AUTOINCREMENT as rowid aliases, or implicit rowid, so those can't be *externalized*. But what about the idea of inserting into two separate DB files? Those INSERTs can then be done in parallel (in different threads), non-interleaved, so probably don't require a VACCUM step, no? Is CTAS from an attached DB to another DB optimized to do page-level copies? Resulting in a non-fragmented continuous span of pages for the copied table?