create table ten(a int);

insert into ten values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);

create table t1 (key1 int, col1 int, filler1 varchar(100), filler varchar(100), key(key1));

insert into t1 

select A.a + B.a* 10 + C.a * 100, 

       A.a + B.a* 10 + C.a * 100, 

       'filler1-data', 'filler2-data' 

from 

  ten A, ten B, ten C;

set histogram_size=100;

set use_stat_tables='preferably';

set optimizer_use_condition_selectivity=4;

analyze table t1 persistent for all;

explain extended select * from t1 where col1 < 500;

+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+

| id   | select_type | table | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra       |

+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+

|    1 | SIMPLE      | t1    | ALL  | NULL          | NULL | NULL    | NULL | 1000 |    50.50 | Using where |

+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+

explain extended select * from t1 where key1<10 ;

+------+-------------+-------+-------+---------------+------+---------+------+------+----------+-----------------------+

| id   | select_type | table | type  | possible_keys | key  | key_len | ref  | rows | filtered | Extra                 |

+------+-------------+-------+-------+---------------+------+---------+------+------+----------+-----------------------+

|    1 | SIMPLE      | t1    | range | key1          | key1 | 5       | NULL |    9 |   100.00 | Using index condition |

+------+-------------+-------+-------+---------------+------+---------+------+------+----------+-----------------------+

explain extended select * from t1 where key1<10 and col1< 500;

+------+-------------+-------+-------+---------------+------+---------+------+------+----------+------------------------------------+

| id   | select_type | table | type  | possible_keys | key  | key_len | ref  | rows | filtered | Extra                              |

+------+-------------+-------+-------+---------------+------+---------+------+------+----------+------------------------------------+

|    1 | SIMPLE      | t1    | range | key1          | key1 | 5       | NULL |    9 |    50.50 | Using index condition; Using where |

+------+-------------+-------+-------+---------------+------+---------+------+------+----------+------------------------------------+

  Breakpoint 31, matching_candidates_in_table (...

(gdb) fini

  Run till exit from #0  matching_candidates_in_table (...

  Value returned is $279 = 4.5445544554455441

Breakpoint 32, table_cond_selectivity (...

(gdb) fini

  0x000000000069e43e in best_extension_by_limited_search (...

  Value returned is $281 = 0.50495049504950495

(gdb) list

  7597	      double partial_join_cardinality= current_record_count *

  7598	                                        pushdown_cond_selectivity;

(gdb) print partial_join_cardinality

  $283 = 2.294775022056661

create table t2 as select * from t1;

explain extended select * from t1,t2 where t1.key1<10 and t1.col1< 500;

  Breakpoint 33, best_access_path (join=0x7fffca5a4088, s=0x7fffca5a5038, remaining_tables=3, idx=0, disable_jbuf=false, record_count=1, pos=0x7fffca5a58b0, loose_scan_pos=0x7ffff7e9fac0) at /home/psergey/dev2/10.0/sql/sql_select.cc:5642

(gdb) p s->table->alias.Ptr

  $288 = 0x7fffca4215f0 "t1"

(gdb) c

  Continuing.

  Breakpoint 33, best_access_path (join=0x7fffca5a4088, s=0x7fffca5a5360, remaining_tables=2, idx=1, disable_jbuf=false, record_count=2.294775022056661, pos=0x7fffca5a59b8, loose_scan_pos=0x7ffff7e9f8b0) at /home/psergey/dev2/10.0/sql/sql_select.cc:5642

(gdb) p s->table->alias.Ptr

  $289 = 0x7fffca5a7270 "t2"