SQLite

The problem was introduced by the 
sqlite3VdbeRecordCompare() optimizations on 2014-03-04
checkin [3325ad5bdc2f81f63b55] (version 3.8.4).
  The KeyInfo.nXField value was
not always accurate for emphemeral tables and so the
sqlite3VdbeFindCompare() function might return one of the
short-circuit comparison routines when in fact the
generalized comparison routine was required.  The problem
became more acute with the introduction of multi-threaded 
sorting on on 2014-09-01 checkin [b1c0f0bc1bd8a347]
(version 3.8.7) because
the new sorter creates tables with lots of extra fields
after the key.

The problem is fixed for version 3.8.8.1 by ensuring that
the KeyInfo.nXField is set correctly.  Two new assert()
statements are added to verify correct KeyInfo.nXField
values moving forward.