Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.1.17
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10.1.29, 10.1.30
Description
It seems MariaDB 10.x.y does not properly implement some part of performance_schema counters. I see that rows_examined, for example, are always zero, even though every instrument and consumer is enabled and statements obviously examined many rows.
Check the following simple test case:
openxs@ao756:~/dbs/maria10.1$ bin/mysql -uroot test
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Reading table information for completion of table and column names
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You can turn off this feature to get a quicker startup with -A
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Welcome to the MariaDB monitor. Commands end with ; or \g.
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Your MariaDB connection id is 2
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Server version: 10.1.17-MariaDB MariaDB Server
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Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.
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Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
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MariaDB [test]> select @@performance_schema;
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+----------------------+
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| @@performance_schema |
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+----------------------+
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| 1 |
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+----------------------+
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1 row in set (0.00 sec)
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MariaDB [test]> create table ttt(id int);
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Query OK, 0 rows affected (0.28 sec)
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MariaDB [test]> insert into ttt values(1);
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Query OK, 1 row affected (0.06 sec)
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 1 row affected (0.05 sec)
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Records: 1 Duplicates: 0 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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\Query OK, 2 rows affected (0.03 sec)
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Records: 2 Duplicates: 0 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 4 rows affected (0.05 sec)
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Records: 4 Duplicates: 0 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 8 rows affected (0.05 sec)
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Records: 8 Duplicates: 0 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 16 rows affected (0.05 sec)
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Records: 16 Duplicates: 0 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 32 rows affected (0.05 sec)
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Records: 32 Duplicates: 0 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 64 rows affected (0.07 sec)
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Records: 64 Duplicates: 0 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 128 rows affected (0.06 sec)
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Records: 128 Duplicates: 0 Warnings: 0
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MariaDB [test]> select thread_id, sql_text, rows_examined from performance_schema.events_statements_history;
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Empty set (0.00 sec)
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MariaDB [test]> update performance_schema.setup_consumers set enabled='Yes';
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Query OK, 8 rows affected (0.00 sec)
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Rows matched: 12 Changed: 8 Warnings: 0
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MariaDB [test]> update performance_schema.setup_instruments set enabled='Yes', timed='Yes';
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Query OK, 430 rows affected (0.01 sec)
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Rows matched: 660 Changed: 430 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 256 rows affected (0.13 sec)
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Records: 256 Duplicates: 0 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 512 rows affected (0.11 sec)
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Records: 512 Duplicates: 0 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 1024 rows affected (0.16 sec)
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Records: 1024 Duplicates: 0 Warnings: 0
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MariaDB [test]> insert into ttt select rand()*10000 from ttt;
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Query OK, 2048 rows affected (0.24 sec)
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Records: 2048 Duplicates: 0 Warnings: 0
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MariaDB [test]> select thread_id, sql_text, rows_examined from performance_schema.events_statements_history;
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+-----------+----------------------------------------------------------------------------+---------------+
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| thread_id | sql_text | rows_examined |
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+-----------+----------------------------------------------------------------------------+---------------+
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| 24 | update performance_schema.setup_consumers set enabled='Yes' | 0 |
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| 24 | update performance_schema.setup_instruments set enabled='Yes', timed='Yes' | 0 |
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| 24 | insert into ttt select rand()*10000 from ttt | 0 |
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| 24 | insert into ttt select rand()*10000 from ttt | 0 |
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| 24 | insert into ttt select rand()*10000 from ttt | 0 |
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| 24 | insert into ttt select rand()*10000 from ttt | 0 |
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+-----------+----------------------------------------------------------------------------+---------------+
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6 rows in set (0.00 sec)
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With a similar test case on Percona Server 5.7.13-6 we get:
mysql> select thread_id, sql_text, rows_examined from performance_schema.events_statements_history;
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+-----------+---------------------------------------------------------------------------------------------+---------------+
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| thread_id | sql_text | rows_examined |
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+-----------+---------------------------------------------------------------------------------------------+---------------+
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| 30 | desc perfromance_schema.events_statements_history | 0 |
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| 30 | desc performance_schema.events_statements_history | 41 |
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| 30 | select thread_id, sql_text, rows_examined from perfromance_schema.events_statements_history | 0 |
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| 30 | insert into ttt select rand()*10000 from ttt | 32 |
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| 30 | insert into ttt select rand()*10000 from ttt | 64 |
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| 30 | insert into ttt select rand()*10000 from ttt | 128 |
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| 30 | insert into ttt select rand()*10000 from ttt | 256 |
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| 30 | insert into ttt select rand()*10000 from ttt | 512 |
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| 30 | insert into ttt select rand()*10000 from ttt | 1024 |
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| 30 | insert into ttt select rand()*10000 from ttt | 2048 |
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+-----------+---------------------------------------------------------------------------------------------+---------------+
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10 rows in set (0.01 sec)
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