MDEV-25251: main.derived_split_innodb fails on ICC release binary

spetrunia · spetrunia · commit 5b678d9ea4aa · 2021-03-31T09:52:28.000+03:00
The code compares two query plans with identical costs, the plan
with lateral is the same as one without. Introduce a small difference
to cost numbers to prefer non-lateral plan in this case.
diff --git a/sql/opt_split.cc b/sql/opt_split.cc
@@ -996,7 +996,7 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count,
     }
     if (spl_plan)
     {
-      if(record_count * spl_plan->cost < spl_opt_info->unsplit_cost)
+      if(record_count * spl_plan->cost < spl_opt_info->unsplit_cost - 0.01)
       {
         /*
           The best plan that employs splitting is cheaper than

Original file line number	Diff line number	Diff line change
`@@ -996,7 +996,7 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count,`
`996`	`996`	`}`
`997`	`997`	`if (spl_plan)`
`998`	`998`	`{`
`999`		`- if(record_count * spl_plan->cost < spl_opt_info->unsplit_cost)`
	`999`	`+ if(record_count * spl_plan->cost < spl_opt_info->unsplit_cost - 0.01)`
`1000`	`1000`	`{`
`1001`	`1001`	`/*`
`1002`	`1002`	`The best plan that employs splitting is cheaper than`