WL#1222: We need to unpack packed MyISAM key blocks once per block when reading keys via my_rprev
Affects: Server-7.1 — Status: Un-Assigned — Priority: Medium
We need to extend mi_rprev to unpack key block once on load. Currently we call _mi_get_last_key for each key read, and if keys are packed, _mi_get_last_key is expensive. Implementing this task will speed up index scan in reverse order by 6-15 times.
Copyright (c) 2000, 2016, Oracle Corporation and/or its affiliates. All rights reserved.