Details
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Type:
Technical task
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Status: Closed
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Priority:
Major
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Resolution: Won't Fix
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Affects Version/s: None
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Fix Version/s: None
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Component/s: None
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Labels:
Description
DROP TABLE IF EXISTS t1; CREATE TABLE t1 (pk INT PRIMARY KEY, c CHAR(10), KEY(c(1))) ENGINE=LevelDB; INSERT INTO t1 VALUES (40,'october'),(41,'february'); SELECT * FROM t1 WHERE c NOT IN ('l', 'f', 'w');
Actual result:
+----+---------+ | pk | c | +----+---------+ | 40 | october | +----+---------+
Expected result:
+----+----------+ | pk | c | +----+----------+ | 41 | february | | 40 | october | +----+----------+
EXPLAIN:
+----+-------------+-------+-------+---------------+------+---------+------+------+----------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+-------+-------+---------------+------+---------+------+------+----------+-------------+ | 1 | SIMPLE | t1 | range | c | c | 2 | NULL | 30 | 100.00 | Using where | +----+-------------+-------+-------+---------------+------+---------+------+------+----------+-------------+
revision-id: psergey@askmonty.org-20130319110939-z2fi30aslmhwxslk revno: 4611 branch-nick: mysql-5.6-leveldb
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The problem can be observed on MyISAM, too! http://bugs.mysql.com/bug.php?id=68750
List of ranges to be scanned (it is surprising that 'w' is not in the list of endpoints, but that itself is not a bug):
"ranges": [
"NULL < c < f",
"f < c < l", — 'february' record falls here
"l < c" — 'october' record falls here
]
The following happens:
...
> ha_leveldb->index_read_map(key='F', find_flag=HA_READ_AFTER_KEY)
get an index record with rkey='F'.
We figure that rkey=key , and since flag=HA_READ_AFTER_KEY, we should step one record forward.
However, HA_READ_AFTER_KEY in the parameter refers to the whole lookup tuple, not to the prefix that's stored in the index.