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RDS terms

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This glossary describes the terms used in ApsaraDB RDS.

A

  • AliSQL

    An independent MySQL branch deeply customized by Alibaba Cloud. In addition to all features of MySQL Community Edition, AliSQL provides many features similar to those of MySQL Enterprise Edition, such as enterprise-level backup and restoration, thread pools, and parallel query. AliSQL also provides Oracle compatibility, for example, the sequence engine. RDS MySQL uses the AliSQL kernel, which delivers all MySQL features together with advanced enterprise-level capabilities such as security, backup, restoration, monitoring, performance optimization, and read-only instances.

    For more information, see Overview of AliSQL features.

  • AliPG

    Alibaba Cloud provides a series of cloud database services that are compatible with PostgreSQL. These services use a unified database kernel, referred to as AliPG. AliPG is compatible with the open source PostgreSQL database and has been commercially available since 2015. It supports the mainstream major versions of PostgreSQL, has run stably for years, and supports many customer workloads within Alibaba Group and on the cloud.

    For more information, see AliPG benefits.

  • Security group

    A security group is a virtual firewall that controls the inbound and outbound traffic of the ECS instances in the security group. After you add a security group to an RDS whitelist, the ECS instances in that security group can access the RDS instance.

    For more information, see Configure a security group for an RDS MySQL instance, Configure a security group for an RDS SQL Server instance, and Configure a security group for an RDS PostgreSQL instance.

  • Pay-as-you-go

    A pay-as-you-go (postpaid) billing method in which you are billed by the hour. Pay-as-you-go is suitable for short-term requirements. You can release an instance immediately after use to reduce costs.

    For more information, see Billable items.

B

  • Semi-synchronous

    After an update initiated by an application is executed on the primary instance, the log is synchronously transmitted to the secondary instance. The transaction is committed once the secondary instance receives the log, without waiting for the secondary instance to execute the log content. If the secondary instance is unavailable or the network between the primary and secondary instances is abnormal, semi-synchronous replication degrades to asynchronous replication.

  • Subscription

    A subscription (prepaid) billing method in which you pay when you create an instance. Subscription is suitable for long-term requirements and is more cost-effective than pay-as-you-go. The longer the subscription duration, the greater the discount.

    For more information, see Billable items.

  • Backup

    To ensure data integrity and reliability, databases require regular automatic backups to guarantee data recoverability.

    For more information, see Back up an RDS MySQL instance, Back up an RDS SQL Server instance, Back up an RDS PostgreSQL instance, and Back up an RDS MariaDB instance.

C

  • CPU utilization

    The CPU resources occupied by the programs, processes, and other workloads running in the system over a period of time.

D

  • DAS

    Database Autonomy Service (DAS) is a cloud service that uses machine learning and expert experience to enable database self-perception, self-recovery, self-optimization, self-O&M, and self-security. DAS eliminates the complexity of database management and the service failures caused by manual operations. It helps ensure that database services are stable, secure, and efficient.

    For more information, see Overview of RDS MySQL performance optimization and diagnostics, Overview of RDS SQL Server performance optimization and diagnostics, and Overview of RDS PostgreSQL performance optimization and diagnostics.

  • DMS

    Data Management (DMS) is a graphical data management tool provided by Alibaba Cloud. It is a data management service that integrates data management, schema management, access security, BI charts, data trends, data tracking, performance and optimization, and server management. DMS supports the management of relational databases and NoSQL databases, such as MySQL, SQL Server, PostgreSQL, MongoDB, and Tair (Redis OSS-compatible). DMS also supports Linux server management.

    For more information, see What is Data Management (DMS)?.

  • DTS

    Data Transmission Service (DTS) is a real-time data streaming service provided by Alibaba Cloud. DTS supports RDBMS, NoSQL, and OLAP databases, integrates data migration, subscription, and synchronization, and provides stable and secure transmission links.

    For more information, see What is Data Transmission Service (DTS).

  • Region

    A region is the geographic location of the cloud service that you purchase. You must specify a region when you purchase an RDS instance. The region cannot be changed after the purchase.

  • Read/write QPS

    The number of SQL statements, including INSERT, SELECT, and UPDATE statements, executed per second when the database performs read and write operations.

  • Dedicated instance

    A dedicated instance provides fully exclusive CPU and memory resources with long-term stable performance. It is not affected by the behavior of other instances on the physical machine. The highest tier of dedicated instance types is the dedicated host, which exclusively occupies all resources of a physical machine.

    For more information, see Instance families.

E

  • ECS

    Elastic Compute Service (ECS) is a virtual computer provided by Alibaba Cloud. Each ECS instance is a virtual computer that features low cost, fast provisioning, simple O&M, diverse configurations, flexible scalability, and high security and reliability. You can deploy websites, blogs, games, and apps on ECS instances. Using ECS together with RDS is a typical application access architecture.

    For more information, see What is ECS?.

  • ESSD

    An Enhanced SSD (ESSD) is a newly launched, ultra-high-performance disk product from Alibaba Cloud. Based on the next-generation distributed block storage architecture and combined with the 25GE network and RDMA technology, ESSDs deliver up to 1 million random read/write IOPS per disk and lower single-way latency. ESSDs are divided into the following three types:

    • PL1 ESSD: an ESSD of the PL1 performance level.

    • PL2 ESSD: compared with PL1, an ESSD of the PL2 performance level delivers approximately 2 times the IOPS and throughput.

    • PL3 ESSD: compared with PL1, an ESSD of the PL3 performance level delivers up to 20 times the IOPS and 11 times the throughput. PL3 ESSDs suit business scenarios that require extremely high ultimate concurrent I/O performance and extremely stable read/write latency.

    For more information, see Storage types.

F

  • Analytic instance

    Data from an RDS MySQL primary instance is automatically synchronized to a MySQL analytic instance. This eliminates the lag of complex analytic queries on RDS MySQL and enables instant, millisecond-level multi-dimensional analysis and business exploration over trillions of data records.

    For more information, see Analytic instances.

  • Service account

    An account used by technical support personnel to provide technical support services. When you request technical support from Alibaba Cloud, you must authorize a service account if the support process requires operations on your database instance. After the authorization validity period ends, the temporary service account is automatically deleted.

    For more information, see Authorize a service account for an RDS MySQL instance and Authorize a service account for an RDS SQL Server instance.

G

H

I

J

  • JDBC

    Java Database Connectivity. JDBC is an application programming interface in the Java language that specifies how client programs access databases.

  • Schema migration

    DTS migrates the schema definitions of the migration objects to the destination instance.

  • Classic network

    Instances are not isolated from each other at the network level and can rely only on their own whitelist policies to block unauthorized access.

  • Cluster Edition

    • RDS MySQL Cluster Edition instances use an architecture that decouples computing from storage and provides one primary node and multiple secondary nodes. The Cluster Edition supports automatic failover, switchover of any secondary node to the primary node, readable secondary nodes, on-demand node addition and removal, multi-zone disaster recovery, node-level monitoring, and cluster node topology management. You can also enable MGR to guarantee RPO=0. Compared with self-managed databases, the Cluster Edition is more economical, flexible, and reliable. For more information, see RDS MySQL Cluster Edition.

    • RDS SQL Server Cluster Edition instances use a high-availability architecture with one primary node and one secondary node. Based on the native AlwaysOn technology of SQL Server, the Cluster Edition decouples computing from storage. It supports adding 1 to 7 read-only instances to the primary instance to implement read/write splitting, which meets high-volume database read requirements. For details, see RDS SQL Server Cluster Edition.

    • RDS PostgreSQL Cluster Edition instances use an architecture that decouples computing from storage and provides one primary node and multiple secondary nodes. The Cluster Edition supports automatic failover, switchover of any secondary node to the primary node, readable secondary nodes, on-demand node addition and removal, multi-zone disaster recovery, node-level monitoring, and cluster node topology management. Compared with self-managed databases, the Cluster Edition is more economical, flexible, and reliable. For details, see RDS PostgreSQL Cluster Edition.

  • Basic Edition

    An RDS Basic Edition instance, also known as a single-node instance, has only one database node. Computing and storage are decoupled, and the instance is highly cost-effective.

    For more information, see RDS MySQL Basic Edition, RDS SQL Server Basic Edition, and RDS PostgreSQL Basic Edition.

K

  • Zone

    A physical area within a region that has an independent power supply and network. There is no substantive difference between the zones in the same region.

L

  • Connections

    The number of TCP connections between clients and an RDS instance. If a client uses a connection pool, the connections between the client and the RDS instance are persistent connections, which are not actively disconnected after they are established and reads and writes are complete. Otherwise, the connections are non-persistent connections, which are actively disconnected after they are established and reads and writes are complete.

    For more information, see Configure connection pooling.

  • Logical I/O

    Read and write operations issued by applications to the file system.

M

  • MaxCompute

    MaxCompute (formerly ODPS) is a fast, fully managed TB/PB-level data warehousing solution for big data computing. It provides comprehensive data import solutions and various classic distributed computing models to quickly handle massive data computing workloads. You can use the data integration service to import RDS data into MaxCompute for large-scale data computing.

    For more information, see What is MaxCompute?.

  • Microsoft AD

    Active Directory (AD). AD is a directory service provided by Microsoft for products such as Windows Standard Server, Windows Enterprise Server, and Microsoft SQL Server. A directory is a hierarchical structure that stores information about objects on the same local area network. For example, AD stores information about user accounts, such as names, passwords, and phone numbers, and allows other authorized users on the same local area network to access this information.

    AD is an important component of the Windows ecosystem. Many large enterprises use domain controllers to implement unified, centralized access management. This is a native management method that enterprises have relied on for a long time.

    For more information, see Join an RDS for SQL Server instance to a self-managed domain and Connect an ApsaraDB RDS for PostgreSQL instance to a self-managed AD domain.

  • MongoDB

    A database service that is stable, reliable, and elastically scalable, and that is fully compatible with the MongoDB protocol. When your data structures are diverse, you can store structured data in RDS and unstructured data in MongoDB to meet the varied storage needs of your business.

    For more information, see What is ApsaraDB for MongoDB?.

  • Slow SQL statement

    An SQL statement that takes a long time to execute.

    For more information, see RDS MySQL slow query log analysis.

O

  • OSS

    Object Storage Service (OSS) is a cloud storage service provided by Alibaba Cloud that offers massive capacity, high security, low cost, and high reliability.

    For more information, see What is OSS?.

  • OpenAPI

    Open Application Programming Interface. OpenAPI is the open application programming interface of ApsaraDB RDS, which is provided for third-party developers.

    For the OpenAPI operations provided by RDS, see API overview.

Q

  • QPS

    Queries Per Second. The number of SQL statements executed by a database per second, including INSERT, SELECT, UPDATE, DELETE, and COMMIT statements.

  • Synchronous mode

    After an update initiated by an application is executed on the primary instance, the log is synchronously transmitted to all secondary instances. A transaction is committed only after at least one secondary instance receives and stores the log. In synchronous mode, the replication mode of an instance always remains strongly synchronous and never degrades to asynchronous mode, regardless of the situation. Only Enterprise Edition (formerly Enterprise Edition for Finance) instances support synchronous mode. The data replication mode of an Enterprise Edition instance cannot be changed.

  • Full data migration

    DTS migrates all historical data of the migration objects from the source RDS instance to the destination RDS instance.

R

  • RAM

    Resource Access Management (RAM), the access control service of Alibaba Cloud, authorizes RAM users to manage RDS instances.

    For more information, see What is RAM.

  • RDS

    Relational Database Service. ApsaraDB RDS is a stable, reliable, and elastically scalable online database service. Based on the Alibaba Cloud distributed file system and high-performance SSD storage, RDS supports the MySQL, SQL Server, PostgreSQL, and MariaDB engines. RDS also provides a full set of solutions for disaster recovery, backup, restoration, monitoring, and migration, eliminating the burden of database O&M.

    For more information, see ApsaraDB RDS.

S

  • Standard SSD

    An elastic block storage device based on a distributed storage architecture. Storing data on standard SSDs implements compute-storage decoupling.

    For more information, see Storage types.

  • SSL

    Secure Sockets Layer (SSL). SSL is a security and confidentiality protocol proposed by Netscape that builds a secure channel between a browser and a web server for data transmission. SSL uses encryption algorithms such as RC4, MD5, and RSA to implement secure communication. The Internet Engineering Task Force (IETF) standardized SSL 3.0 and renamed the standard Transport Layer Security (TLS). RDS provides SSL for MySQL, SQL Server, and PostgreSQL. You can use the server-side root certificate provided by RDS to verify whether the database service at the target address and port is provided by RDS. This effectively prevents man-in-the-middle attacks. In addition, RDS lets you enable and update server-side SSL certificates so that you can replace SSL certificates as needed to ensure security and validity.

    For details, see RDS MySQL SSL encryption, RDS SQL Server SSL encryption, and RDS PostgreSQL SSL encryption.

  • SSMS

    SQL Server Management Studio (SSMS) is an integrated environment for managing the SQL Server infrastructure. It provides tools for configuring, monitoring, and administering SQL Server instances. SSMS also provides tools for deploying, monitoring, and upgrading data layer components, such as the databases and data warehouses used by applications, and for generating queries and scripts.

    For more information, see Connect to an SQL Server instance.

  • Instance

    A database service process that independently occupies physical memory. An instance is a virtualized database server. You can configure different memory sizes, disk space, and database types for an instance. You can create and manage multiple databases in one instance.

  • Database

    A logical unit created in an RDS instance. A database is a collection of data that is stored together in a certain way, can be shared by multiple users, has minimal redundancy, and is independent of applications. You can think of a database as a warehouse for storing data. You can create multiple databases in one instance, and database names must be unique within an instance.

  • Database proxy

    The RDS database proxy is a network proxy service located between the database server and the application server. It proxies all requests from the application server when the server accesses the database. The database proxy is highly available, high-performing, maintainable, and easy to use. It also provides advanced features such as automatic read/write splitting, transaction splitting, and connection pools.

    For more information, see What are database proxies?.

  • Deadlock

    DeadLock. Because of the special mechanism of transactions, a transaction locks a specific resource while modifying it to prevent other concurrent transactions from modifying the resource, which ensures data consistency. Deadlocks are usually caused by multiple transactions competing for the same resources.

  • Sequential I/O

    Read and write operations performed on a disk in sequence.

  • Random I/O

    Read and write operations performed on a disk in random order.

T

  • Tair

    ApsaraDB for Tair (Redis OSS-compatible) provides persistent in-memory database services. When business traffic is heavy, the combination of ECS, RDS, and Tair supports more read requests while reducing response time.

    For more information, see What is Tair (Redis OSS-compatible)?.

  • TDE

    Transparent Data Encryption. RDS provides transparent data encryption (TDE) for MySQL, SQL Server, and PostgreSQL, which performs real-time I/O encryption and decryption on data files. Data is encrypted before it is written to disk and decrypted when it is read from disk into memory. TDE does not increase the size of data files, and developers can use TDE without changing any applications.

    For more information, see RDS MySQL TDE, RDS SQL Server TDE, and RDS PostgreSQL TDE.

  • TPM

    Transactions Per Minute. The number of transactions executed by a database per minute.

  • TPS

    Transactions Per Second. The number of transactions executed by a database per second, measured by the number of successful COMMIT operations.

V

  • VPC

    Virtual Private Cloud (VPC). A VPC is an isolated network environment whose security and performance are both superior to those of the traditional classic network.

    For more information, see What is VPC.

W

  • Physical I/O

    Read and write operations issued by the file system to a disk.

X

  • Performance Insight

    Performance Insight is a tool in DAS dedicated to load monitoring, correlation analysis, and performance tuning of RDS instances. It provides a simple and intuitive way to evaluate database load, find the root cause of performance issues, and improve database stability.

    For more information, see Performance Insight.

Y

  • Asynchronous replication

    When an application initiates an update request, that is, an operation to add, delete, or modify data, the primary instance responds to the application immediately after it completes the operation. At the same time, the primary instance asynchronously replicates the data to the secondary instance. Therefore, in asynchronous replication mode, the unavailability of the secondary instance does not affect operations on the primary instance. However, the unavailability of the primary instance may cause data inconsistency between the primary and secondary instances.

  • Emergency RDS instance

    Database Disaster Recovery supports the emergency recovery feature of RDS MySQL. This feature is based on Copy Data Management (CDM) technology. By enabling a Database Disaster Recovery sandbox, you can quickly create a temporary sandbox instance as an emergency recovery database instance, which makes backup data quickly available. Reads and writes between multiple sandbox instances do not affect each other, nor do they affect the source database. This feature can be used for recovery drills, development and testing, query analysis, and emergency disaster recovery.

    For more information, see Emergency recovery for ApsaraDB RDS for MySQL.

Z

  • Read-only instance

    Read-only instances meet high-volume database read requirements. Their read capacity scales elastically, offloads database load, and increases application throughput.

    For more information, see Overview of read-only ApsaraDB RDS for MySQL instances, Overview of read-only ApsaraDB RDS for SQL Server instances, and Overview of read-only ApsaraDB RDS for PostgreSQL instances.

  • Read-only QPS

    The number of SQL statements executed per second when the database performs read-only operations, including SELECT statements only.

  • Incremental data migration

    On the basis of full migration, DTS synchronizes the incremental update data of the source RDS instance to the destination RDS instance. Incremental data migration enables smooth data migration without interrupting your self-managed applications.

  • Character set

    A character set is a collection of letters and symbols in a database, together with their encoding rules.

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