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  1. MariaDB Server
  2. MDEV-30355

set names effects performance significantly when compiling function

Details

    Description

      Having a different character set when compiling a function can impact the performance of the function significantly.
      The function itself has the proper character sets for input parameters and the result.

      Have a look at the attached function. In the following sequence you would observe that the execution is almost 10 times slower for just 10000 invocation and the only difference is the character set set when compiling the function. 

      root@lukav::/vagrant# mysql test --init-command='set names utf8mb4' < ./set_names_test.sql 
      root@lukav::/vagrant# time mysql test --init-command='set names utf8mb4' -e "SELECT set_names_test(CONCAT('a', seq)) from seq_1_to_10000" > /dev/null 
       
      		 
      real	0m0,190s
      		 
      user	0m0,007s
      		 
      sys	0m0,004s
      		 
       
      		 
       
      		 
      root@lukav::/vagrant# mysql test --init-command='set names utf8' < ./set_names_test.sql 
      root@lukav::/vagrant# time mysql test --init-command='set names utf8mb4' -e "SELECT set_names_test(CONCAT('a', seq)) from seq_1_to_10000" > /dev/null 
       
      		 
      real	0m8,008s
      		 
      user	0m0,000s
      		 
      sys	0m0,010s

      If this is expected behaviour it should be well documented, but I couldn't find anything on the subject.

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          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-29988 Major performance regression with 10.6.11

          • Blocker - Blocks development and/or testing work, production could not run.
          • Closed

          Activity

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            serg Sergei Golubchik added a comment -

            Please, try again when 10.8.7 is out. May be it's MDEV-29988

            serg Sergei Golubchik added a comment - Please, try again when 10.8.7 is out. May be it's MDEV-29988
            serg Sergei Golubchik added a comment -

            10.8.7 is out. Did it help?

            serg Sergei Golubchik added a comment - 10.8.7 is out. Did it help?
            lukav Anton Avramov added a comment -

            It seams so.

            I wasn't able to reproduce the effect with the latest version, so I guess it is fixed.

            Thank you very much

            lukav Anton Avramov added a comment - It seams so. I wasn't able to reproduce the effect with the latest version, so I guess it is fixed. Thank you very much

            People

              serg Sergei Golubchik
              lukav Anton Avramov
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                Updated:
                Resolved:

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