Details
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Task
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
Description
Reading from information_schema.PARAMETERS table in MariaDB is slower than MySQL by a factor of 20x in the best of cases, and deteriorates linearly in MariaDB once the number of reading threads exceeds the number of available cores, whereas in MySQL the deterioration remains more-or-less flat.
The following table shows relative performance running mysqlslap against the dataset provided in the attached sql file cs0401486-test.sql with this series of commands
for i in 1 5 20 100
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do
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mysqlslap -q "select * from information_schema.parameters where SPECIFIC_NAME = 'aaa_sp50001'" -i 10 -c $i
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done
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Tests conducted in CentOS 7 machines with 1G RAM and approx. 800 real IOPS with one and four Intel i7-9750H cores @ 2.592GHz, average times reported:
CoresThreads MDB 6.7 MySQL 8 Diff %
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1 1 0.193 0.008 2413%
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1 5 0.901 0.015 6007%
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4 1 0.171 0.004 4275%
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4 5 0.296 0.007 4229%
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4 20 1.159 0.066 1756%
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4 100 19.017 0.340 5593%
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Timings all on MariaDB 10.6.7. Confirmed on 10.6.8, 10.7.4, and 10.8.3 in Rocky Linux.
Attachments
Issue Links
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- Closed
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- relates to
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Activity
Implemented an optimization suggested by psergei:
commit ac6d5ff303323a45b0125a02f41c760b30d0e1fd (HEAD -> bb-10.11-MDEV-29104, origin/bb-10.11-MDEV-29104)
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Author: Oleg Smirnov <olernov@gmail.com>
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Date: Mon Sep 19 21:36:09 2022 +0700
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MDEV-29104 Optimize queries to INFORMATION_SCHEMA.PARAMETERS/ROUTINES
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For queries like
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"SELECT * FROM INFORMATION_SCHEMA.PARAMETERS
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WHERE SPECIFIC_NAME='proc_name'"
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and
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"SELECT * FROM INFORMATION_SCHEMA.ROUTINES
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WHERE ROUTINE_NAME='proc_name'"
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there is a possibility to avoid loading a stored procedure code and
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parsing it to retrieve parameters.
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If the name of the procedure/function is specified explicitly then
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it is possible to filter out routines that do not match at
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an early stage.
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queries Average query time
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queries improved2-MDEV-29104 improved1-MDEV-20609 10.11-vanilla
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1 0.006 0.138 0.136
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5 0.033 0.283 0.293
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20 0.158 2.152 2.146
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100 0.8 10.802 10.868
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Short overview of how the Data Dictionary architecture has been reworked in MySQL 8.0: https://www.slideshare.net/StleDeraas/data-dictionary-pl17. One of the reasons mentioned is low performance of queries to INFORMATION_SCHEMA tables.