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(EOL), 10.3(EOL), 10.4(EOL), 10.5, 10.6
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None
Description
When stored procedure is cached, the bytes are counted towards global memory, which can be
retrieved with
select variable_value from information_schema.global_status where variable_name='MEMORY_USED'; |
This is wrong, as the caches are per-session (THD::sp_proc_cache etc). Thus populating cache should result in increase of "information_schema.session_status where variable_name='MEMORY_USED'" instead, which is not happening
Commands below create and execute a dummy stored procedure, and measure increase of global and session memory for that operation.
session memory increases by 96 bytes , global memory by some 10K . Session memory increase only happens first time around, i.e if you create another procedure, and execute it, session memory will increase by 0 bytes, but global memory by some 12K. (Those numbers are taken from current debug 10.3 on my box.
mysql> select variable_value into @global_mem_used from information_schema.global_status where variable_name='MEMORY_USED';
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Query OK, 1 row affected (0.00 sec)
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mysql> select variable_value into @local_mem_used from information_schema.session_status where variable_name='MEMORY_USED';
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Query OK, 1 row affected (0.00 sec)
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mysql> create procedure sp1() BEGIN END;
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Query OK, 0 rows affected (0.01 sec)
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mysql> call sp1();
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Query OK, 0 rows affected (0.00 sec)
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mysql> select variable_value-@global_mem_used as global_mem_diff from information_schema.global_status where variable_name='MEMORY_USED';
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+-----------------+
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| global_mem_diff |
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+-----------------+
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| 10888 |
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+-----------------+
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1 row in set (0.00 sec)
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mysql> select variable_value-@local_mem_used as local_mem_diff from information_schema.session_status where variable_name='MEMORY_USED';
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+----------------+
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| local_mem_diff |
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+----------------+
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| 96 |
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+----------------+
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1 row in set (0.00 sec)
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Attachments
Issue Links
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