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  1. MariaDB Server
  2. MDEV-25286

Docu: aria status in docu does not reflect reality

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Details

    • Bug
    • Status: Open (View Workflow)
    • Major
    • Resolution: Unresolved
    • 10.5.9
    • N/A
    • Documentation
    • None
    • n.a.

    Description

      1. Docu here: https://mariadb.com/kb/en/aria-status-variables/
      could be more clear that:

      • Aria_pagecache_blocks_unused is the current state
      • Aria_pagecache_blocks_used is a high water mark from somewhen in the past

      2. Docu here: https://mariadb.com/kb/en/aria-status-variables/
      and here: https://mariadb.com/kb/en/flush/#flush-status

      states that this 3 status variables:

      Aria_pagecache_blocks_not_flushed
      Aria_pagecache_blocks_unused
      Aria_pagecache_blocks_used

      can be reset with flush status. This does IMHO technically not make sense (at least for not_flushed and unused, possibly it does make sense for the high water mark used) but experiments show that flush status does not reset the values:

      root@mariadb-105 [test] SQL> show global status like 'aria%';
      -----------------------------------------+

      Variable_name Value

      -----------------------------------------+

      Aria_pagecache_blocks_not_flushed 234
      Aria_pagecache_blocks_unused 15396
      Aria_pagecache_blocks_used 251
      Aria_pagecache_read_requests 102435
      Aria_pagecache_reads 50
      Aria_pagecache_write_requests 33141
      Aria_pagecache_writes 100
      Aria_transaction_log_syncs 20

      -----------------------------------------+
      8 rows in set (0.001 sec)

      root@mariadb-105 [test] SQL> flush status;
      Query OK, 0 rows affected (0.000 sec)

      root@mariadb-105 [test] SQL> show global status like 'aria%';
      -----------------------------------------+

      Variable_name Value

      -----------------------------------------+

      Aria_pagecache_blocks_not_flushed 202
      Aria_pagecache_blocks_unused 15396
      Aria_pagecache_blocks_used 251
      Aria_pagecache_read_requests 102435
      Aria_pagecache_reads 50
      Aria_pagecache_write_requests 33141
      Aria_pagecache_writes 132
      Aria_transaction_log_syncs 20

      -----------------------------------------+
      8 rows in set (0.001 sec)

      root@mariadb-105 [test] SQL> flush tables;
      Query OK, 0 rows affected (0.042 sec)

      root@mariadb-105 [test] SQL> flush status;
      Query OK, 0 rows affected (0.000 sec)

      root@mariadb-105 [test] SQL> show global status like 'aria%';
      -----------------------------------------+

      Variable_name Value

      -----------------------------------------+

      Aria_pagecache_blocks_not_flushed 0
      Aria_pagecache_blocks_unused 15647
      Aria_pagecache_blocks_used 251
      Aria_pagecache_read_requests 102435
      Aria_pagecache_reads 50
      Aria_pagecache_write_requests 33142
      Aria_pagecache_writes 335
      Aria_transaction_log_syncs 21

      -----------------------------------------+
      8 rows in set (0.001 sec)

      This should be fixed or at least clarified...

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            greenman Ian Gilfillan
            oli Oli Sennhauser
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            Dates

              Created:
              Updated:

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