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# basic concept

The glossary on this page defines the core concepts behind MySQL to help you build a mental model of how MySQL works and understand what the documentation refers to when it uses certain terms.

- ACID compliance

    ACID compliance is an acronym for the four words Atomiciy, Consistency, Isolation, and Durability, and is a set of database characteristics consisting of atomicity, consistency, isolation, and durability that ensure efficient completion of database transactions.

- ACLs

    Access Control Lists or ACLs are lists of user permissions that control access to system resources.

- Connection Status Metric (connection status metric)

    The connection state metric is a measure of the number of threads created, connected, and running relative to the database connection limit.

- DBaaS (Database as a Service)
  
    Database as a Service, Managed Database Service, or DBaaS for short, is a cloud service that allows users to access cloud database systems on a subscription basis without owning a personal cloud data system.

-E2EE

    The English full name is End-to-end encryption, which is end-to-end encryption, or E2EE for short, is a communication system that encrypts messages and message services for everyone, except the user who receives the message and the user who sends the message.

- Failover

    Failover is a high availability (HA) mechanism that monitors servers for failure and reroutes traffic or operations to a standby server if the primary server fails.

- High Availability

    High Availability (HA) is an infrastructure design approach focused on reducing downtime and eliminating single points of failure.

- Hot Standby

    Hot standby is the act of listening for when a primary node fails so that a standby node can take its place.

- Index vs. Sequential Reads Metric (index and sequential read metrics)

    The Index vs. Sequential Reads metric graph shows reads using indexes as a proportion of the total reads for all databases (schemas) on the master.

- LUKS Disk Encryption (LUKS Disk Encryption)

    Linux Unified Key Set Disk Encryption (LUKS) is an open source disk encryption specification for Linux storage devices.

- Machine Type

    A machine type is a group of virtualized hardware resources for a virtual machine (VM) instance.

- Node Plan (node ​​plan)

    A node plan, database or cluster configuration is a hardware plan for a node specification.

- Operations Throughput Metric

    The Operational Throughput metric is a measure of the throughput of get, insert, update, and delete operations for all databases on the server.

- Point-In-Time-Recovery (recovery point in time)

    Point-in-time recovery, or PITR for short, ensures that automatic backups are made so that data created in a previous state of the server can be recovered.

- Port

    A port is a communication endpoint for a network connection. A port is identified by the port number used by each transport protocol.

- Read-Only Node (read-only node)

    Read-only nodes are replicas of the cluster master.

- SQL Mode

    SQL mode or sql_mode is a MySQL system variable used to configure the operational characteristics of the MySQL server.

- SSL Certificate

    An SSL certificate is a digital certificate that describes a website's identity.

- Standby Node

    A standby node is a node that is set to be idle while in hot standby mode.

- Tag

    Tags are keywords associated with resources that help manage resource ownership and organize finding and manipulating resources.