Commit d752b1a8 authored by unknown's avatar unknown
Browse files

Merge spetrunia@bk-internal.mysql.com:/home/bk/mysql-5.1-opt 

into  mysql.com:/home/psergey/mysql-5.1-bug22393


mysql-test/t/range.test:
  Auto merged
sql/sql_select.cc:
  Auto merged
mysql-test/r/range.result:
  Manual merge
parents 86b4ca84 5e34af32

mysql-test/r/range.result

+14 −0
Original line number Diff line number Diff line
@@ -941,3 +941,17 @@ item started price 
A1	2005-11-01 08:00:00	1000.000

A1	2005-11-15 00:00:00	2000.000

DROP TABLE t1;

create table t1 (a int);

insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);

create table t2 (a int, b int, filler char(100));

insert into t2 select A.a + 10 * (B.a + 10 * C.a), 10, 'filler' from t1 A,

t1 B, t1 C where A.a < 5;

insert into t2 select 1000, b, 'filler' from t2;

alter table t2 add index (a,b);

select 'In following EXPLAIN the access method should be ref, #rows~=500 (and not 2)' Z;

Z

In following EXPLAIN the access method should be ref, #rows~=500 (and not 2)

explain select * from t2 where a=1000 and b<11;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	t2	ref	a	a	5	const	502	Using where

drop table t1, t2;

mysql-test/t/range.test

+27 −0
Original line number Diff line number Diff line
@@ -740,3 +740,30 @@ SELECT * FROM t1 WHERE item='A1' AND started<='2005-12-02 00:00:00'; 
DROP TABLE t1;



# End of 5.0 tests



# BUG#22393 fix: Adjust 'ref' estimate if we have 'range' estimate for

#                a smaller scan interval

create table t1 (a int);

insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);



create table t2 (a int, b int, filler char(100));

insert into t2 select A.a + 10 * (B.a + 10 * C.a), 10, 'filler' from t1 A,

t1 B, t1 C where A.a < 5;



insert into t2 select 1000, b, 'filler' from t2;

alter table t2 add index (a,b);

# t2 values 

#  ( 1  , 10, 'filler')

#  ( 2  , 10, 'filler')

#  ( 3  , 10, 'filler')

#  (... , 10, 'filler')

#   ...

#  (1000, 10, 'filler') - 500 times



# 500 rows, 1 row



select 'In following EXPLAIN the access method should be ref, #rows~=500 (and not 2)' Z;

explain select * from t2 where a=1000 and b<11;



drop table t1, t2;

sql/sql_select.cc

+23 −0
Original line number Diff line number Diff line
@@ -3717,7 +3717,30 @@ best_access_path(JOIN *join, 
            {

              /* Check if we have statistic about the distribution */

              if ((records= keyinfo->rec_per_key[max_key_part-1]))

              {

                /* 

                  Fix for the case where the index statistics is too

                  optimistic: If 

                  (1) We're considering ref(const) and there is quick select

                      on the same index, 

                  (2) and that quick select uses more keyparts (i.e. it will

                      scan equal/smaller interval then this ref(const))

                  (3) and E(#rows) for quick select is higher then our

                      estimate,

                  Then 

                    We'll use E(#rows) from quick select.



                  Q: Why do we choose to use 'ref'? Won't quick select be

                  cheaper in some cases ?

                  TODO: figure this out and adjust the plan choice if needed.

                */

                if (!found_ref && table->quick_keys.is_set(key) &&    // (1)

                    table->quick_key_parts[key] > max_key_part &&     // (2)

                    records < (double)table->quick_rows[key])         // (3)

                  records= (double)table->quick_rows[key];



                tmp= records;

              }

              else

              {

                /*