Details
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Bug
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Status: Closed (View Workflow)
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Minor
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Resolution: Fixed
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10.0.27
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None
Description
EXPLAIN EXTENDED always returns 0.00 percentage of filtered rows if there is a range condition over the column for which no statistics has been collected:
The following test case demonstrates the problem:
set use_stat_tables='preferably';
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set optimizer_use_condition_selectivity=3;
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create table t1(col1 char(32));
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insert into t1 values ('a'),('b'),('c'),('d'), ('e'),('f'),('g'),('h');
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analyze table t1 persistent for columns () indexes ();
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explain extended
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select * from t1 where col1 > 'b' and col1 < 'd';
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MariaDB [test]> explain extended
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-> select * from t1 where col1 > 'b' and col1 < 'e';
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+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+
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| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+
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| 1 | SIMPLE | t1 | ALL | NULL | NULL | NULL | NULL | 8 | 0.00 | Using where |
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+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+
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