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MDEV-26901: Estimation for filtered rows less precise ... #4

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In Histogram_json_hb::point_selectivity(), do return selectivity of 0.0
when the histogram says so.

The logic of "Do not return 0.0 estimate as it causes a multiply-by-zero
meltdown in cost and cardinality calculations" is moved into
records_in_column_ranges() where it is one *once* per column pair (as
opposed to doing once per range, which can cause the error to add-up
to large number when there are many ranges)
This commit is contained in:
Sergei Petrunia
2022-01-11 17:09:55 +03:00
parent db8f15be93
commit dae20dde4e
6 changed files with 42 additions and 6 deletions
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20
mysql-test/main/statistics_json.result
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@ -8264,3 +8264,23 @@ ANALYZE SELECT * FROM t1 WHERE f > '00:01:00';
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 1000 1000.00 50.00 50.00 Using where
drop table t1;
#
# MDEV-26901: Estimation for filtered rows less precise ... #4
#
create table t1 (f int);
insert into t1 values
(7),(5),(0),(5),(112),(9),(9),(7),(5),(9),
(1),(7),(0),(6),(6),(2),(1),(6),(169),(7);
select f from t1 where f in (77, 1, 144, 73, 14, 12);
f
1
1
set histogram_type= JSON_HB;
analyze table t1 persistent for all;
Table Op Msg_type Msg_text
test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status OK
analyze select f from t1 where f in (77, 1, 144, 73, 14, 12);
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 20 20.00 10.00 10.00 Using where
drop table t1;