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Percona Server for MySQL
Improved InnoDB I/O scalability
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      • The Percona XtraDB storage engine
      • List of features available in Percona Server for MySQL releases
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      • Improved InnoDB I/O scalability
        • Version specific information
        • System variables
          • innodb_flush_method
        • Status variables
      • Adaptive network buffers
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      • Prefix index queries optimization
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      • The ProcFS plugin
      • Binary logs and replication improvements
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      • Improved MEMORY storage engine
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      • Limiting the disk space used by binary log files
      • Support for PROXY protocol
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      • XtraDB changed page tracking
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          • Using the Key Management Interoperability Protocol (KMIP)
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      • User statistics
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      • Percona MyRocks introduction
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      • TokuDB introduction
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      • Migrate and removing the TokuDB storage engine
      • Percona TokuBackup
      • Release notes index
      • Percona Server for MySQL 8.0.32-24 (2023-03-20)
      • Percona Server for MySQL 8.0.31-23 (2023-02-09)
      • Percona Server for MySQL 8.0.30-22 Update (2022-11-21)
      • Percona Server for MySQL 8.0.30-22 (2022-11-21)
      • Percona Server for MySQL 8.0.29-21 (2022-08-08)
      • Percona Server for MySQL 8.0.28-20 (2022-06-20)
      • Percona Server for MySQL 8.0.28-19 (2022-05-12)
      • Percona Server for MySQL 8.0.27-18 (2022-03-02)
      • Percona Server for MySQL 8.0.26-17 (2022-01-26)
      • Percona Server for MySQL 8.0.26-16 (2021-10-20)
      • Percona Server for MySQL 8.0.25-15 (2021-07-13)
      • Percona Server for MySQL 8.0.23-14 (2021-05-12)
      • Percona Server for MySQL 8.0.22-13 (2020-12-14)
      • Percona Server for MySQL 8.0.21-12 (2020-10-13)
      • Percona Server for MySQL 8.0.20-11 (2020-07-21)
      • Percona Server for MySQL 8.0.19-10 (2020-03-23)
      • Percona Server for MySQL 8.0.18-9
      • Percona Server for MySQL 8.0.17-8
      • Percona Server for MySQL 8.0.16-7
      • Percona Server for MySQL 8.0.15-6
      • Percona Server for MySQL 8.0.15-5
      • Percona Server for MySQL 8.0.14
      • Percona Server for MySQL 8.0.13-4
      • Percona Server for MySQL 8.0.13-3
      • Percona Server for MySQL 8.0.12-2rc1
      • List of variables introduced in Percona Server for MySQL 8.0
      • Development of Percona Server for MySQL
      • Trademark policy
      • Index of INFORMATION_SCHEMA tables
      • Frequently asked questions
      • Copyright and licensing information
      • Glossary

    • Version specific information
    • System variables
      • innodb_flush_method
    • Status variables

    Improved InnoDB I/O scalability¶

    Because InnoDB is a complex storage engine it must be configured properly in order to perform at its best. Some points are not configurable in standard InnoDB. The goal of this feature is to provide a more exhaustive set of options for XtraDB.

    Version specific information¶

    • 8.0.12-1: The feature was ported from Percona Server for MySQL 5.7.

    Note

    Implemented in Percona Server for MySQL 8.0.13-4, max checkpoint age has been removed because the information is identical to log capacity.

    System variables¶

    innodb_flush_method¶

    Option Description
    Command-line Yes
    Config file Yes
    Scope Global
    Dynamic No
    Data type Enumeration
    Default NULL
    Allowed values fsync, O_DSYNC, O_DIRECT, O_DIRECT_NO_FSYNC, littlesync, nosync

    The following values are allowed:

    * `fdatasync`: use `fsync()` to flush data, log, and parallel doublewrite files.
    
    * `O_SYNC`: use `O_SYNC` to open and flush the log and parallel doublewrite files; use `fsync()` to flush the data files. Do not use `fsync()` to flush the parallel doublewrite file.
    
    * `O_DIRECT`: use O_DIRECT to open the data files and `fsync()` system call to flush data, log, and parallel doublewrite files.
    
    * `O_DIRECT_NO_FSYNC`: use O_DIRECT to open the data files and parallel doublewrite files, but does not use the `fsync()` system call to flush the data files, log files, and parallel doublewrite files. Do not use this option for the *XFS* file system.
    
    * `ALL_O_DIRECT`: use O_DIRECT to open data files, log files, and parallel doublewrite files
    and use `fsync()` to flush the data files but not the log files or
    parallel doublewrite files. This option is recommended when *InnoDB* log files are big (more than 8GB), otherwise, there may be performance degradation.
    

    Note

    When using this option on ext4, the filesystem variable innodb_log_block_size should be set to 4096 (default log-block-size in ext4) in order to avoid the unaligned AIO/DIO warnings.

    Starting from Percona Server for MySQL 8.0.20-11, the innodb_flush_method affects doublewrite buffers exactly the same as in MySQL 8.0.20.

    Status variables¶

    The following information has been added to SHOW ENGINE INNODB STATUS to confirm the checkpointing activity:

    The max checkpoint age
    The current checkpoint age target
    The current age of the oldest page modification which has not been flushed to disk yet.
    The current age of the last checkpoint
    ...
    ---
    LOG
    ---
    Log sequence number 0 1059494372
    Log flushed up to   0 1059494372
    Last checkpoint at  0 1055251010
    Max checkpoint age  162361775
    Checkpoint age target 104630090
    Modified age        4092465
    Checkpoint age      4243362
    0 pending log writes, 0 pending chkp writes
    ...
    

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    Last update: 2023-01-12
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