Documentation Home
MySQL 9.4 Reference Manual
Related Documentation Download this Manual
PDF (US Ltr) - 41.2Mb
PDF (A4) - 41.3Mb
Man Pages (TGZ) - 262.8Kb
Man Pages (Zip) - 368.8Kb
Info (Gzip) - 4.1Mb
Info (Zip) - 4.1Mb


MySQL 9.4 Reference Manual  / The InnoDB Storage Engine  /  InnoDB and the ACID Model

17.2 InnoDB and the ACID Model

TheACID model is a set of database design principles that emphasize aspects of reliability that are important for business data and mission-critical applications. MySQL includes components such as theInnoDB storage engine that adhere closely to the ACID model so that data is not corrupted and results are not distorted by exceptional conditions such as software crashes and hardware malfunctions. When you rely on ACID-compliant features, you do not need to reinvent the wheel of consistency checking and crash recovery mechanisms. In cases where you have additional software safeguards, ultra-reliable hardware, or an application that can tolerate a small amount of data loss or inconsistency, you can adjust MySQL settings to trade some of the ACID reliability for greater performance or throughput.

The following sections discuss how MySQL features, in particular theInnoDB storage engine, interact with the categories of the ACID model:

  • A: atomicity.

  • C: consistency.

  • I:: isolation.

  • D: durability.

Atomicity

Theatomicity aspect of the ACID model mainly involvesInnoDBtransactions. Related MySQL features include:

Consistency

Theconsistency aspect of the ACID model mainly involves internalInnoDB processing to protect data from crashes. Related MySQL features include:

Isolation

Theisolation aspect of the ACID model mainly involvesInnoDBtransactions, in particular theisolation level that applies to each transaction. Related MySQL features include:

Durability

Thedurability aspect of the ACID model involves MySQL software features interacting with your particular hardware configuration. Because of the many possibilities depending on the capabilities of your CPU, network, and storage devices, this aspect is the most complicated to provide concrete guidelines for. (And those guidelines might take the form of“buy new hardware”.) Related MySQL features include:

  • TheInnoDB doublewrite buffer. SeeSection 17.6.4, “Doublewrite Buffer”.

  • Theinnodb_flush_log_at_trx_commit variable.

  • Thesync_binlog variable.

  • Theinnodb_file_per_table variable.

  • The write buffer in a storage device, such as a disk drive, SSD, or RAID array.

  • A battery-backed cache in a storage device.

  • The operating system used to run MySQL, in particular its support for thefsync() system call.

  • An uninterruptible power supply (UPS) protecting the electrical power to all computer servers and storage devices that run MySQL servers and store MySQL data.

  • Your backup strategy, such as frequency and types of backups, and backup retention periods.

  • For distributed or hosted data applications, the particular characteristics of the data centers where the hardware for the MySQL servers is located, and network connections between the data centers.