Comment 4 for bug 1410410

commit 18dc2fbb910604ae826c3585f40a2994e24b88c4
Author: Krunal Bauskar <email address hidden>
Date: Tue Sep 8 10:54:23 2015 +0530

    - bug#1410410: innodb_fake_changes cause unknown error code 1000

      innodb_fake_changes allows user to dry run the workload.
      Dry run will execute the query part but will not make any modifications
      to DB there-by helping in warmup the cache. This feature eventually helps
      newly added slave to catch-up with replication faster.

      To faciliate this, search mode in-case of pessimistic insert is modified
      from BTR_MODIFY_TREE to BTR_SEARCH_TREE (newly added for this purpose).
      This mode switch takes S-latch instead of X-latch as S-latch is less
      restrictive and so is acceptable for dry-run workload requirement.

      Same search mode was used for insert too but without special handling
      in insert part and so even though pessimistic mode was invoked it caused
      optimistic insert to execute
        if (mode != BTR_MODIFY_TREE) {
                optimistic
        } else {
                pessimistic
        }

      with mode = BTR_SEARCH_TREE it defaulted to optimistic.

      We made the code consistent with previous revision to ensure that
      search_mode and mode (used for insert) are segregated to avoid re-use.

Pull-Request: #147