MDEV-25830 optimizer_use_condition_selectivity=4 sometimes produces worse plan than optimizer_use_condition_selectivity=1

The issue was that calc_cond_selectivity_for_table prefered ranges with
many parts and when deciding on which selectivity to use.

Fixed by going through ranges according to the number of rows in the range.

This ensures that selectivity from ranges with few rows will be prefered
over ranges with many rows for indexes that uses the same columns.

1 files changed, 55 insertions, 0 deletions

diff --git a/mysql-test/main/mdev-25830.result b/mysql-test/main/mdev-25830.result
new file mode 100644
index 00000000000..d9840d20474
--- /dev/null
+++ b/mysql-test/main/mdev-25830.result
@@ -0,0 +1,55 @@
+SET SESSION DEFAULT_STORAGE_ENGINE='InnoDB';
+set @innodb_stats_persistent_save= @@innodb_stats_persistent;
+set @innodb_stats_persistent_sample_pages_save=
+@@innodb_stats_persistent_sample_pages;
+set global innodb_stats_persistent= 1;
+set global innodb_stats_persistent_sample_pages=100;
+set optimizer_use_condition_selectivity=1;
+analyze SELECT sysapproval_approver0.`sys_id`
+FROM   ((sysapproval_approver sysapproval_approver0
+INNER JOIN task task1
+ON sysapproval_approver0.`sysapproval` = task1.`sys_id`
+                    AND (( task1.`sys_domain_path` = '/'
+                            OR task1.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
+                            OR task1.`sys_domain_path` LIKE '!!!/!!!/%' )))
+INNER JOIN task task2
+ON task1.`parent` = task2.`sys_id`
+                   AND (( task2.`sys_domain_path` = '/'
+                           OR task2.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
+                           OR task2.`sys_domain_path` LIKE '!!!/!!!/%' )))
+WHERE  task2.`sys_id` LIKE '8e7792a7dbfffb00fff8a345ca961934%'
+       AND ( sysapproval_approver0.`sys_domain_path` = '/'
+              OR sysapproval_approver0.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
+              OR sysapproval_approver0.`sys_domain_path` LIKE '!!!/!!!/%' )
+ORDER  BY sysapproval_approver0.`order`
+LIMIT  0, 50 ;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	r_rows	filtered	r_filtered	Extra
+1	SIMPLE	task2	range	PRIMARY,sys_class_name_2,sys_domain_path	PRIMARY	96	NULL	1	0.00	100.00	100.00	Using where; Using temporary; Using filesort
+1	SIMPLE	task1	ref	PRIMARY,task_parent,sys_class_name_2,sys_domain_path	task_parent	99	mdev25830.task2.sys_id	1	NULL	100.00	NULL	Using index condition; Using where
+1	SIMPLE	sysapproval_approver0	ref	sysapproval_approver_ref5,sys_domain_path,sysapproval_approver_CHG1975376	sysapproval_approver_ref5	99	mdev25830.task1.sys_id	1	NULL	100.00	NULL	Using index condition; Using where
+set optimizer_use_condition_selectivity=4;
+analyze SELECT sysapproval_approver0.`sys_id`
+FROM   ((sysapproval_approver sysapproval_approver0
+INNER JOIN task task1
+ON sysapproval_approver0.`sysapproval` = task1.`sys_id`
+                    AND (( task1.`sys_domain_path` = '/'
+                            OR task1.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
+                            OR task1.`sys_domain_path` LIKE '!!!/!!!/%' )))
+INNER JOIN task task2
+ON task1.`parent` = task2.`sys_id`
+                   AND (( task2.`sys_domain_path` = '/'
+                           OR task2.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
+                           OR task2.`sys_domain_path` LIKE '!!!/!!!/%' )))
+WHERE  task2.`sys_id` LIKE '8e7792a7dbfffb00fff8a345ca961934%'
+       AND ( sysapproval_approver0.`sys_domain_path` = '/'
+              OR sysapproval_approver0.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
+              OR sysapproval_approver0.`sys_domain_path` LIKE '!!!/!!!/%' )
+ORDER  BY sysapproval_approver0.`order`
+LIMIT  0, 50 ;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	r_rows	filtered	r_filtered	Extra
+1	SIMPLE	task2	range	PRIMARY,sys_class_name_2,sys_domain_path	PRIMARY	96	NULL	1	0.00	98.00	100.00	Using where; Using temporary; Using filesort
+1	SIMPLE	task1	ref	PRIMARY,task_parent,sys_class_name_2,sys_domain_path	task_parent	99	mdev25830.task2.sys_id	1	NULL	100.00	NULL	Using index condition; Using where
+1	SIMPLE	sysapproval_approver0	ref	sysapproval_approver_ref5,sys_domain_path,sysapproval_approver_CHG1975376	sysapproval_approver_ref5	99	mdev25830.task1.sys_id	1	NULL	100.00	NULL	Using index condition; Using where
+set global innodb_stats_persistent= @innodb_stats_persistent_save;
+set global innodb_stats_persistent_sample_pages=
+@innodb_stats_persistent_sample_pages_save;