MDEV-18478 ANALYZE for statement should show selectivity of ICP, part#1

(Based on the original patch by Jason Cu)

Part #1:
- Add ha_handler_stats::{icp_attempts,icp_match}, make
  handler_index_cond_check() increment them.
- ANALYZE FORMAT=JSON now prints r_icp_filtered based on these counters.

mysql-test/main/analyze_format_json.test

@@ -269,4 +269,80 @@ where
 set join_cache_level=@tmp;
 drop table t10, t11;
 
+--echo #
+--echo # MDEV-18478: ANALYZE for statement should show selectivity of
+--echo #             pushed index condition
+--echo #
+create table t12 (a int, b varchar(10), c int, index(a,b), index(c));
+create table t13 (a int not null primary key, b int, index(b));
 
+insert into t12(a,b,c) values (1,"abc",100),
+                              (2,"abd",200),(2,"bfd",300),(2,"efg",400),
+                              (3,"abc",410),(3,"def",420),(3,"ghi",430),(3,"jkl",440),
+                              (4,"abc",600),(4,"def",700),(4,"ghi",800),(4,"jkl",900);
+insert into t13(a,b) values(1,1),(2,2),(3,3),(4,4),(5,5);
+analyze table t12;
+analyze table t13;
+
+-- echo # eq key condition only, no pushed condition
+# no r_pushed_condition in output because there is no pushed condition
+# a=2 qualifies 3 rows (r_rows=3)
+--source include/analyze-format.inc
+analyze format=json select * from t12 where t12.a=2;
+
+-- echo # pushed index condition
+# key condition a=2 gets 3 rows
+# pushed condition b like '%f%' filters down to two of the 3 rows (66.667%)
+--source include/analyze-format.inc
+analyze format=json select * from t12 where t12.a=2 and t12.b like '%f%';
+
+-- echo # rowid filter only, no pushed condition
+# key condition a=2 gets 3 rows
+# rowid filter condition between 400 and 500 qualifies 1 of the 3 key rows (33.33%)
+--source include/analyze-format.inc
+analyze format=json select * from t12 where t12.a=2 and t12.c
+between 400 and 500;
+
+-- echo # pushed index condition and rowid filter
+# key condition a=2 gets 3 rows
+# pushed condition b like '%f%' filters down to 2 of the 3 key rows (66.667%)
+# rowid filter condition between 400 and 500 filters down to 1 of the icp 2 rows (50%)
+--source include/analyze-format.inc
+analyze format=json select * from t12 where t12.a=2 and t12.c
+between 400 and 500 and t12.b like '%f%';
+
+-- echo # pushed index condition on the inner table (t12) of a join
+# for inner table t12, key t12.a=t13.a
+# for t13.a=1, 1 matching row in t12, 100% filtered by the index condition (t12.b like '%f%')
+# for t13.a=2, 3 matching rows in t12, 66% filtered by the index cond
+# r_rows_idx=2 (average 4 (1+3)/2 scans = 2 rows per scan)
+# r_icp_filtered=50 (4 rows total, 2 survive the icp, both in the second scan)
+--source include/analyze-format.inc
+analyze format=json select * from t13,t12
+where t13.a between 1 and 2 and t12.a=t13.a and t12.b like '%f%';
+
+-- echo # rowid filter on inner table of a join, no ICP
+# inner table t12, key t12.a=t13.a
+# for t13.a=1, 1 matching row in t12, 0% survive the rowid filter (t12.c between 400 and 500)
+# for t13.a=2, 3 matching rows in t12, 33% (1/3) survive the rowid filter
+# rowid_filter r_lookups=2 (1+3 / 2 loops)
+# rowid_filter r_selectivity_pct = 25 (1 / (1+3))
+--source include/analyze-format.inc
+analyze format=json select * from t13,t12 where t13.b between 1 and 2 and t12.a=t13.a and t12.c
+between 400 and 450;
+
+-- echo # rowid filter and ICP on inner table of a join
+# inner table t12, key t12.a=t13.a
+# for t13.a=1, 1 matching row in t12, 100% filtered by the index condition (t12.b like '%f%')
+# for t13.a=2, 3 matching rows in t12, 66% filtered by the index cond
+# r_rows_idx=2 (average 4 (1+3)/2 scans = 2 rows per scan)
+# r_icp_filtered=50 (4 rows total, 2 survive the icp, both in the second scan)
+# for t13.a=1, 0 rows after ICP
+# for t13.a=2, 2 rows after ICP, 1 survives the rowid_filter (t12.c bewteen 400 and 500)
+# rowid_filter r_lookups=2 (2 / 2 loops)
+# rowid_filter r_selectivity_pct = 50 (1 survived / 2 rows after ICP)
+--source include/analyze-format.inc
+analyze format=json select * from t13,t12 where t13.b between 1 and 2 and t12.a=t13.a and t12.c
+between 400 and 450 and t12.b like '%f%';
+
+drop table t12,t13;