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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N/A
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None
Description
Note: I'm setting it to Major rather than Critical even though it's an issue in a new feature (MDEV-33151), because as described in the comment to MDEV-33151 and in MDEV-33916 (closed as "won't fix"), semantics of Key_read_hits/Key_read_misses is incomprehensible anyway, so while it can be reasonably assumed that the behavior described here is wrong, it's hard to specify what would be the expected result.
set @userstat.save= @@userstat; |
set global userstat= 1; |
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create table t (a int, key(a desc)); |
insert into t values (1),(2),(3),(4),(5),(6); |
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flush user_statistics, table_statistics;
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explain select * from t where a > 3; |
select * from t where a > 3; |
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select key_read_hits, key_read_misses from information_schema.user_statistics where user = 'root'; |
select key_read_hits, key_read_misses from information_schema.table_statistics where table_schema = 'test'; |
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explain select * from t where a > 10; |
select * from t where a > 10; |
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select key_read_hits, key_read_misses from information_schema.user_statistics where user = 'root'; |
select key_read_hits, key_read_misses from information_schema.table_statistics where table_schema = 'test'; |
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# Cleanup
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set global userstat= @userstat.save; |
drop table t; |
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bb-11.5-MDEV-33151-userstat 8f786ad4671368fa5e92c82cb47fb124ff06c14c |
explain select * from t where a > 3; |
id select_type table type possible_keys key key_len ref rows Extra |
1 SIMPLE t range a a 5 NULL 3 Using where; Using index |
select * from t where a > 3; |
a
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6
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5
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4
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select key_read_hits, key_read_misses from information_schema.user_statistics where user = 'root'; |
key_read_hits key_read_misses
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0 0
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select key_read_hits, key_read_misses from information_schema.table_statistics where table_schema = 'test'; |
key_read_hits key_read_misses
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0 0
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explain select * from t where a > 10; |
id select_type table type possible_keys key key_len ref rows Extra |
1 SIMPLE t range a a 5 NULL 1 Using where; Using index |
select * from t where a > 10; |
a
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select key_read_hits, key_read_misses from information_schema.user_statistics where user = 'root'; |
key_read_hits key_read_misses
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0 0
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select key_read_hits, key_read_misses from information_schema.table_statistics where table_schema = 'test'; |
key_read_hits key_read_misses
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0 0
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So, neither hits nor misses are detected. With an ASC instead of a DESC key and otherwise the same test case, the values are incremented.
Attachments
Issue Links
- is caused by
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MDEV-33151 Add more columns to TABLE_STATISTICS and USER STATS
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- Closed
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