Fixed in the linked branch. This was just superficial: the EXPLAIN used the chunk size, but the actual query used the LIMIT value, which is chunk size - 1. Now the EXPLAIN uses the LIMIT value too.
Fixed in the linked branch. This was just superficial: the EXPLAIN used the chunk size, but the actual query used the LIMIT value, which is chunk size - 1. Now the EXPLAIN uses the LIMIT value too.