Details
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Bug
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Status: Open (View Workflow)
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Major
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Resolution: Unresolved
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10.2, 10.3, 10.4, 10.5
Description
Here is a simple dataset used:
CREATE TABLE t1(a INT); |
INSERT INTO t1 SELECT 5 from seq_1_to_99; |
INSERT INTO t1 VALUES (10); |
set optimizer_use_condition_selectivity=4; |
set use_stat_tables='preferably'; |
set histogram_size=255; |
ANALYZE TABLE t1 PERSISTENT FOR ALL; # Collect EITS |
MariaDB [test]> EXPLAIN EXTENDED SELECT * FROM t1 WHERE a < 5;
|
+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+
|
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
|
+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+
|
| 1 | SIMPLE | t1 | ALL | NULL | NULL | NULL | NULL | 100 | 98.44 | Using where |
|
+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+
|
1 row in set, 1 warning (0.001 sec)
|
Well there are no rows with a < 5 and we end up with filtered as 98.44
MariaDB [test]> EXPLAIN EXTENDED SELECT * FROM t1 WHERE a > 5;
|
+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+
|
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
|
+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+
|
| 1 | SIMPLE | t1 | ALL | NULL | NULL | NULL | NULL | 100 | 99.22 | Using where |
|
+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+
|
1 row in set, 1 warning (0.002 sec)
|
Well there is 1 row with a > 5 and we end up with filtered as 99.22 %