Hi,

Jonathan Tan wrote:

The binary search to lookup a packfile offset from a .idx file
(which involves disk reads) would take longer for all lookups (not
just lookups for missing blobs) - I think I prefer keeping the lists
separate, to avoid pessimizing the (likely) usual case where the
relevant blobs are all already in local repo storage.

Another relevant operation is looking up objects by offset or
index_nr.  The current implementation involves building an in-memory
reverse index on demand by reading the idx file and sorting it by
offset --- see pack-revindex.c::create_pack_revindex.  This takes O(n
log n) time where n is the size of the idx file.

That said, it could be avoided by storing an on-disk reverse index
with the pack.  That's something we've been wanting to do anyway.

Thanks,
Jonathan