TEMPORARY PUSH: Changing all cost calculation to be given in ms10.7-selectivity-old

- Added tests/check_costs.pl, a tool to verify optimizer cost calculations.
  - Most costs has been found with this program. All steps to calculate
    the new costs are documented in Docs/optimizer.costs
- User optimizer_cost variables are given in usec (as individual
  costs can be very small). Internally they are stored in ms.
- Changed DISK_READ_COST (was DISK_SEEK_BASE_COST) from a hard disk cost
  (9 ms) to common SSD cost (400MB/sec).
- Changed the following handler functions to return IO_AND_CPU_COST.
  This makes it easy to apply different cost modifiers in ha_..time()
  functions for io and cpu costs.
  - scan_time()
  - rndpos_time()
  - keyread_time()
- Enhanched keyread_time() to calculate the full cost of reading of a set
  of keys with a given number of ranges and optionall number of blocks that
  need to be accessed.
- Removed read_time() as keyread_time() + rndpos_time() is the same thing.
- Added the following new optimizer_variables:
  - optimizer_scan_lookup_cost
  - optimizer_row_lookup_cost
  - optimizer_index_lookup_cost
  - optimizer_disk_read_cost
- Added include/my_tracker.h  ; Useful include file to quickly test costs
  of a function.
- Tuned sequence and heap engine costs (rest will be done in an updated
  commit)

1 files changed, 11 insertions, 0 deletions

diff --git a/storage/myisam/ha_myisam.h b/storage/myisam/ha_myisam.h
index 3843004cc6e..6ceabd8d9c5 100644
--- a/storage/myisam/ha_myisam.h
+++ b/storage/myisam/ha_myisam.h
@@ -102,6 +102,17 @@ class ha_myisam final : public handler
   int remember_rnd_pos();
   int restart_rnd_next(uchar *buf);
   void position(const uchar *record);
+  void optimizer_costs_updated()
+  {
+#ifdef QQQQ
+    /*
+      MyISAM row lookup costs are slow as the row data is on a not cached file.
+      The following number was found by check_costs.pl when using 1M rows
+      and all rows are cached
+    */
+    optimizer_row_lookup_cost*= 3.0;
+#endif
+  }
   int info(uint);
   int extra(enum ha_extra_function operation);
   int extra_opt(enum ha_extra_function operation, ulong cache_size);