Update cost for hash and cached joins

The old code did not't correctly add TIME_FOR_COMPARE to rows that are
part of the scan that will be compared with the attached where clause.

Now the cost calculation for hash join and full join cache join are
identical except for HASH_FANOUT (10%)

The cost for a join with keys is now also uniform.
The total cost for a using a key for lookup is calculated in one place as:

(cost_of_finding_rows_through_key(records) + records/TIME_FOR_COMPARE)*
record_count_of_previous_row_combinations + startup_cost

startup_cost is the cost of a creating a temporary table (if needed)

Best_cost now includes the cost of comparing all WHERE clauses and also
cost of joining with previous row combinations.

Other things:
- Optimizer trace is now printing the total costs, including testing the
  WHERE clause (TIME_FOR_COMPARE) and comparing with all previous rows.
- In optimizer trace, include also total cost of query together with the
  final join order. This makes it easier to find out where the cost was
  calculated.
- Old code used filter even if the cost for it was higher than not using a
  filter. This is not corrected.
- When rebasing on 10.11, I noticed some changes to access_cost_factor
  calculation. These changes was not picked as the coming changes
  to filtering will make that code obsolete.

1 files changed, 2 insertions, 2 deletions

diff --git a/mysql-test/main/join.result b/mysql-test/main/join.result
index e621197692a..8f75105c30d 100644
--- a/mysql-test/main/join.result
+++ b/mysql-test/main/join.result
@@ -892,7 +892,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	
 show status like 'Last_query_cost';
 Variable_name	Value
-Last_query_cost	4.016090
+Last_query_cost	6.016090
 select 'The cost of accessing t1 (dont care if it changes' '^';
 The cost of accessing t1 (dont care if it changes
 The cost of accessing t1 (dont care if it changes^
@@ -906,7 +906,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	B	eq_ref	PRIMARY	PRIMARY	4	test.A.b	1	
 show status like 'Last_query_cost';
 Variable_name	Value
-Last_query_cost	28.016090
+Last_query_cost	34.016090
 select '^^: The above should be ~= 20 + cost(select * from t1). Value less than 20 is an error' Z;
 Z
 ^^: The above should be ~= 20 + cost(select * from t1). Value less than 20 is an error