This topic describes the terms that are used in ApsaraDB RDS.
AliSQL is an independent MySQL branch that is developed by Alibaba Cloud. AliSQL provides all the features of the MySQL Community Edition. AliSQL also provides some similar features that you can find in the MySQL Enterprise Edition. These similar features include enterprise-grade backup and restoration, thread pools, and parallel queries. In addition, AliSQL provides Oracle-compatible features, such as the Sequence engine. ApsaraDB RDS for MySQL with AliSQL provides all the features of MySQL. ApsaraDB RDS for MySQL also provides a wide range of advanced features that are developed by Alibaba Cloud. These advanced features include enterprise-grade security, backup and restoration, monitoring, performance optimization, and read-only instances.
For more information, see Overview of AliSQL features.
AliPG is a unified database engine that is developed by Alibaba Cloud. Alibaba Cloud provides the following two PostgreSQL-compatible database services that run AliPG: ApsaraDB RDS and ApsaraDB for MyBase. Since the commercial rollout of AliPG in 2015, AliPG shows consistently stable performance and processes a large volume of workloads within Alibaba Group and for Alibaba Cloud customers. AliPG supports the following major PostgreSQL versions: PostgreSQL 9.4, PostgreSQL 10.0, PostgreSQL 11.0, PostgreSQL 12.0, and PostgreSQL 13.0.
For more information, see AliPG benefits.
- ApsaraDB for MyBase
ApsaraDB for MyBase is developed by Alibaba Cloud to provide custom, optimized database services for enterprises. An ApsaraDB for MyBase dedicated cluster consists of multiple hosts. These hosts can be ECS instances of the ecs.i2.xlarge instance type or ECS Bare Metal instances. ApsaraDB for MyBase can meet more of your business requirements than fully managed database solutions.
For more information, see What is ApsaraDB for MyBase?
- asynchronous mode
After an add, delete, or modify operation originated from an application is complete on a primary RDS instance, the primary RDS instance immediately responds to the application. At the same time, the primary RDS instance asynchronously replicates the added, deleted, or modified data to the secondary RDS instances that are attached to the primary RDS instance. In asynchronous mode, the unavailability of the secondary RDS instances does not interrupt the workloads on the primary RDS instance. However, the unavailability of the primary RDS instance may cause data inconsistencies between the primary RDS instance and the secondary RDS instances.
For data integrity and reliability purposes, regular automatic backups must be performed on an RDS instance to ensure that the data of the RDS instance can be restored.
For more information, see Overview.
- Basic Edition
The RDS Basic Edition is cost-effective. In this edition, your database system consists of only one primary RDS instance, and computing is separated from storage.
For more information, see RDS Basic Edition.
- character set
A character set is a collection of letters, symbols, and rules that are used to encode the letters and symbols in a database.
- classic network
RDS instances in the classic network cannot be isolated by using network settings. You can block unauthorized access to these instances only by configuring IP address whitelists or security groups for these instances.
- Cluster Edition
The RDS Cluster Edition is developed based on the native SQL Server technology AlwaysOn and is supported only in SQL Server 2017. In this edition, computing is separated from storage, and you can create read-only RDS instances to implement read/write splitting. After you create read-only RDS instances, you can apply for a read-only routing endpoint, which is used to implement read/write splitting. By default, each read-only RDS instance is assigned an independent internal endpoint. The internal endpoint of a read-only RDS instance is used to connect only to the read-only RDS instance.
For more information, see Cluster Edition.
Connections indicate the number of connections that are established over TCP between a database client and an RDS instance. If a connection pool is enabled on the database client, the connections between the database client and the RDS instance are long-lived. Unlike short-lived connections, long-lived connections are not actively closed after the read and write requests over the connections are processed.
For more information, see Set the connection pool type of an ApsaraDB RDS for MySQL instance.
- CPU utilization
CPU utilization indicates the resources that the programs and processes occupy in a database system over a specific period of time.
A database is a logical unit of an RDS instance. It is a set of data that is stored in an organized manner and with minimal redundancy. The data in databases is independent of the data on applications. The data can be shared among a number of authorized users. In simple words, a database is a data warehouse that is used to store data. You can create a number of databases on each RDS instance. Databases on the same RDS instance must have unique names.
- database proxy
A dedicated proxy resides between a database system and an application. The dedicated proxy receives requests from the application and routes the requests to the primary and read-only RDS instances in the database system. The dedicated proxy is easy to use and maintain, and provides high availability and high performance. The dedicated proxy also provides advanced features, such as automatic read/write splitting, transaction splitting, and connection pool.
For more information, see What are dedicated proxies.
Database Autonomy Service (DAS) is a cloud service that uses machine learning and expert experience to automate perception, healing, optimization, operations and maintenance (O&M), and security for databases. DAS simplifies database management and prevents service failures that may be caused by manual operations. DAS also helps ensure the stability, security, and efficiency of your database service.
For more information, see DAS overview.
Database Backup (DBS) is a cost-effective backup service that can provide continuous protection for RDS instances.
For more information, see What is DBS?
When you run a transaction to modify specific resources, the resources are locked to prevent other concurrent transactions from modifying the resources and ensure data consistency. This lock is known as a deadlock. In most cases, deadlocks are triggered if a number of transactions compete to modify the same resources.
- dedicated RDS instance
A dedicated RDS instance is an instance that exclusively occupies the allocated CPU and memory resources. The performance of a dedicated RDS instance remains stable and is not affected by the other instances that are deployed on the same physical host. The dedicated host instance family is the top configuration of the dedicated instance family. A dedicated host RDS instance occupies all resources on the physical host on which the dedicated host instance is deployed.
For more information, see Instance families.
- disaster recovery RDS instance
If you use ApsaraDB RDS for common business scenarios that require high data reliability or for financial business scenarios that require compliance with specific regulatory requirements, you can create a disaster recovery RDS instance for the primary RDS instance in your database system. ApsaraDB RDS supports disaster recovery RDS instances only for the MySQL database engine. The disaster recovery RDS instance synchronizes data from the primary RDS instance in real time by using DTS. The primary RDS instance and the disaster recovery RDS instance are deployed based on a high-availability architecture. If the primary RDS instance and its secondary RDS instances become inaccessible due to unexpected exceptions such as natural disasters, your database system fails over to the disaster recovery RDS instance. In this case, the disaster recovery RDS instance becomes the primary RDS instance. After you update the endpoint configuration on the connected application, the application can immediately connect to the new primary RDS instance.
For more information, see Create a disaster recovery ApsaraDB RDS for MySQL instance.
Data Management (DMS) is a GUI-based tool that is developed by Alibaba Cloud. DMS supports data management, schema management, server management, access control, business intelligence (BI) charting, data trend analysis, data tracking, and performance monitoring and optimization. DMS can be used to manage relational databases, such as MySQL, SQL Server, PostgreSQL, MongoDB, and Redis databases. DMS can also be used to manage NoSQL databases and Linux-based servers.
For more information, see Overview.
Data Transmission Service (DTS) is a data streaming service that is developed by Alibaba Cloud. DTS can be used to migrate, subscribe to, and synchronize data between relational databases, NoSQL databases, and online analytical processing (OLAP) databases over stable, secure transmission links.
For more information, see What is DTS?
To maximize performance, ApsaraDB RDS provides database services accessible over internal networks to Elastic Compute Service (ECS) instances that are deployed in the same region. The combination of ECS and ApsaraDB RDS is a typical service access architecture.
For more information, see What is ECS?
- emergency RDS instance
DBS provides an emergency recovery feature. This feature allows DBS to obtain the data backup files of an RDS instance and generate snapshots. Then, DBS can produce an emergency RDS instance in less than 1 minute. The emergency RDS instance is also known as a DBS sandbox instance.
For more information, see Create a sandbox instance for emergency recovery.
- Enterprise Edition
The RDS Enterprise Edition is suitable for enterprises. In this edition, your database system consists of one primary RDS instance and two secondary RDS instances. Data is replicated from the primary RDS instance to the secondary RDS instances in synchronous mode to ensure data consistency and finance-grade reliability.
For more information, see Enterprise Edition.
Enhanced SSDs (ESSDs) are a new type of SSD that is developed by Alibaba Cloud based on the next-generation distributed block storage architecture. ESSDs are integrated with 25 Gigabit Ethernet and remote direct memory access (RDMA) technologies. ESSDs can reduce one-way latencies and process up to 1 million read and write requests at random per second. ESSDs come in three performance levels (PLs) on the ApsaraDB RDS buy page:
- ESSD PL1: This refers to an ESSD of PL1.
- ESSD PL2: An ESSD of PL2 delivers input/output operations per second (IOPS) and throughput that are about two times higher than the IOPS and throughput that are delivered by an ESSD of PL1.
- ESSD PL3: An ESSD of PL3 delivers IOPS that is up to 20 times higher than the IOPS that is delivered by an ESSD of PL1. An ESSD of PL3 also delivers throughput that is up to 11 times higher than the throughput that is delivered by an ESSD of PL1. ESSDs of PL3 are suitable for business scenarios in which highly concurrent requests must be processed with high I/O performance and at low read and write latencies.
For more information, see Storage types.
- full data migration
You can migrate the data of all objects from a source RDS instance to a destination RDS instance by using DTS. This is called a full data migration.
- High-availability Edition
In the RDS High-availability Edition, a secondary RDS instance is provided as a standby for the primary RDS instance. Data is replicated from the primary RDS instance to the secondary RDS instance in semi-synchronous mode. If the primary RDS instance becomes faulty, your database system fails over to the secondary RDS instance.
For more information, see High-availability Edition.
I/O is short for input and output. I/O indicates the read and write operations that are performed on a disk.
- incremental data migration
After all data of a source RDS instance is migrated to a destination RDS instance, you can synchronize the incremental data of the source RDS instance to the destination RDS instance by using DTS. This is called an incremental data migration. Incremental data migration allows you to migrate data between RDS instances without downtime.
Input/output operations per second (IOPS) indicate the number of read and write operations that are performed to read and write 4 KB of data on a block storage device per second.
- IP address whitelist
An IP address whitelist consists of the IP addresses and CIDR blocks that are granted access to an RDS instance. The IP address whitelists that you configure for an RDS instance can ensure high-level access control and security protection for the RDS instance. We recommend that you update the configured IP address whitelists on a regular basis.
For more information, see Configure an IP address whitelist for an ApsaraDB RDS for MySQL instance.
Java Database Connectivity (JDBC) is a Java-based API that is used to connect to an RDS instance from a database client.
- local SSD
Local SSDs are deployed on the same physical host as the RDS instance to which the local SSDs are attached. You can store data on local SSDs to reduce I/O latencies.
For more information, see Storage types.
- Logical I/O
Logical I/O indicates the read and write requests that are sent from an application to a file system.
MaxCompute, which is formerly known as ODPS, is a fully managed computing platform that can process terabytes or petabytes of data at high speeds. MaxCompute supports comprehensive data import solutions and various classic distributed computing models. These solutions and models can be used to import large amounts of data from RDS instances into MaxCompute. Then, you can process the data by using MaxCompute.
For more information, see What is MaxCompute?
- Microsoft AD
Active Directory (AD) is a directory service that is developed by Microsoft for various Microsoft services, such as Windows Standard Server, Windows Enterprise Server, and Microsoft SQL Server. A directory is a hierarchical structure that stores information about the objects on the same LAN. For example, AD stores information about user accounts, such as names, passwords, and phone numbers, and allows other authorized users on the same LAN to access this information.
AD is an important part of the Windows ecosystem. A number of large enterprises rely on the domain control mechanism that is provided in the Windows ecosystem to plan and implement centralized access management.
ApsaraDB for MongoDB is a stable, reliable, and scalable database service that is fully compatible with MongoDB. You can store structured data in ApsaraDB RDS and unstructured data in ApsaraDB for MongoDB to meet your diverse storage requirements.
For more information, see What is ApsaraDB for MongoDB?
- open API
ApsaraDB RDS provides an API for third-party developers.
For more information, see List of operations by function.
Object Storage Service (OSS) is a secure, cost-effective, and high-durability cloud storage service that is provided by Alibaba Cloud. OSS allows you to store large amounts of data in the cloud.
For more information, see What is OSS?
A pay-as-you-go RDS instance is charged on an hour basis based on your actual resource usage. We recommend that you select the pay-as-you-go billing method for short-term use. If you no longer need a pay-as-you-go RDS instance, you can release the RDS instance to reduce costs.
For more information, see Pricing, billable items, and billing methods.
- performance insight
Performance insight is a feature of DAS. This feature provides instance-level load monitoring, association analysis, and performance optimization. This feature helps you evaluate the loads on an RDS instance and troubleshoot performance issues to increase the stability of the RDS instance.
- physical I/O
Physical I/O indicates the read and write operations that are initiated by a file system to a disk.
Queries per second (QPS) indicate the number of SQL statements that are executed on an RDS instance per second. These SQL statements include INSERT, SELECT, UPDATE, DETELE, and COMMIT.
Resource Access Management (RAM) is a service that is provided by Alibaba Cloud to manage user identities and resource access permissions. You can grant the permissions on specific RDS instances to RAM users.
For more information, see What is RAM?
- random I/O
Random I/O indicates the read and write operations that are randomly performed on a disk.
ApsaraDB Relational Database Service (RDS) is a stable, reliable, and scalable online database service that is provided by Alibaba Cloud. ApsaraDB RDS is designed based on the Apsara Distributed File System and high-performance SSDs of Alibaba Cloud. ApsaraDB RDS supports the MySQL, SQL Server, PostgreSQL, PPAS (highly compatible with Oracle), and MariaDB TX database engines. ApsaraDB RDS provides a full suite of solutions for disaster recovery, backup, restoration, monitoring, and migration to facilitate database O&M.
For more information, see What is ApsaraDB RDS?
- RDS instance
An RDS instance is a database process that exclusively occupies the allocated memory resources on a physical host. An RDS instance can be considered a virtual database server. You can specify different memory sizes, storage capacities, and database engines for different RDS instances. You can create and manage a number of databases on each RDS instance.
- read-only RDS instance
If a database system processes a large number of read requests from an application, you can create read-only RDS instances that are used to offload read requests from the primary RDS instance of the database system. This increases the read capability of the database system and the throughput of the application.
For more information, see Overview of read-only ApsaraDB RDS for MySQL instances.
- read-only QPS
Read-only QPS indicates the number of SELECT statements that are executed on an RDS instance per second when only read requests are allowed.
- read and write QPS
Read and write QPS indicates the number of INSERT, SELECT, and UPDATE statements that are executed on an RDS instance per second when both read and write requests are allowed.
- recycle bin
Some RDS instances are moved to the recycle bin after they expire or are released. You can unlock, rebuild, or destroy the RDS instances in the recycle bin.
For more information, see Manage ApsaraDB RDS for MySQL instances in the recycle bin.
ApsaraDB for Redis is a database service that supports a hybrid of memory and hard disks for data persistence. You can use ECS, ApsaraDB RDS, and ApsaraDB for Redis together to handle a large number of read requests within a short period of time.
For more information, see What is ApsaraDB for Redis?
A region is the geographic location to which the RDS instance that you purchase belongs. When you purchase an RDS instance, you must specify a region. The region of an RDS instance cannot be changed after the instance is created.
- schema migration
DTS can be used to migrate the schemas of objects from a source RDS instance to a destination RDS instance.
- security group
A security group is a virtual firewall that is used to control the inbound and outbound traffic of specific Elastic Compute Service (ECS) instances. After you add a security group to an RDS instance, all ECS instances in the security group can access the RDS instance.
For more information, see Configure a security group for an ApsaraDB RDS for MySQL instance.
- semi-synchronous mode
After an update operation originated from an application is complete on a primary RDS instance, the update log is synchronized to all the secondary RDS instances that are attached to the primary RDS instance. The update transaction is considered committed after the secondary RDS instances receive the update log rather than after the update log is replayed on the secondary RDS instances. If the secondary RDS instances are unavailable or the communication between the primary RDS instance and the secondary RDS instances is abnormal, the semi-synchronous mode degrades to the asynchronous mode.
- Sequential I/O
Sequential I/O indicates the contiguous read and write operations that are sequentially performed on a disk.
- service account
The service account of an RDS instance is used by Alibaba Cloud technical support engineers to troubleshoot issues on the RDS instance. If Alibaba Cloud technical support engineers need to perform operations on an RDS instance during the troubleshooting process, you must grant permissions to the service account of the RDS instance. ApsaraDB RDS deletes the service account at the expiration time that you specify.
For more information, see Authorize the service account of an ApsaraDB RDS for MySQL instance.
- slow SQL
If an SQL statement requires a long period of time to run, the SQL statement is considered a slow SQL statement.
For more information, see Slow Query Logs.
Secure Sockets Layer (SSL) is developed by Netscape to establish an encrypted connection between a web server and a browser. SSL supports various encryption algorithms, such as RC4, MD5, and RSA. The Internet Engineering Task Force (IETF) has standardized SSL 3.0. After the standardization, SSL 3.0 is renamed as TLS. ApsaraDB RDS supports SSL for the MySQL, SQL Server, and PostgreSQL database engines. ApsaraDB RDS provides a server root certificate. You can use this server root certificate to check whether the database service that you access by using the destination IP address and port is provided by ApsaraDB RDS. This way, you can effectively defend against man-in-the-middle attacks. For security and validity purposes, ApsaraDB RDS allows you to enable and update the server SSL certificate.
For more information, see Configure SSL encryption on an ApsaraDB RDS for MySQL instance.
SQL Server Management Studio (SSMS) is an integrated environment that is used to manage SQL infrastructure. You can use SSMS to configure, monitor, and manage database instances that run SQL Server. In addition, SSMS provides various tools that can generate queries and scripts to deploy, monitor, and upgrade the components at the data layer. These components include the databases and data warehouses that run on applications.
- standard SSD
A standard SSD is an elastic block storage device that is designed based on a distributed storage architecture. You can store data on standard SSDs to separate computing from storage.
For more information, see Storage types.
A subscription RDS instance is an instance that you can subscribe to for a specified period of time and pay for up front. For long-term use, the subscription billing method is more cost-effective than the pay-as-you-go billing method. You can receive larger discounts for longer subscription periods.
For more information, see Pricing, billable items, and billing methods.
- synchronous mode
After an update operation originated from an application is complete on a primary RDS instance, the update log is synchronized to all the secondary RDS instances that are attached to the primary RDS instance. The update transaction is considered committed after at least one of the secondary RDS instances receives and stores the update log. The synchronous mode never degrades to the asynchronous mode. The synchronous mode is supported only in the RDS Enterprise Edition. In addition, if you are using the RDS Enterprise Edition, the data replication mode cannot be changed.
ApsaraDB RDS supports transparent data encryption (TDE) for the MySQL and SQL Server database engines. TDE is used to instantly encrypt and decrypt the data files that are read from and write to an RDS instance. TDE can encrypt data before the data is written to the disk and can decrypt data before the data is read from the disk to the memory. TDE does not increase the size of the data files. You can use TDE without the need to modify the connected application.
For more information, see Configure TDE for an ApsaraDB RDS for MySQL instance.
Transactions per minute (TPM) indicate the number of transactions that are run on an RDS instance per minute.
Transactions per second (TPS) indicate the number of committed transactions that are run on an RDS instance per second.
A virtual private cloud (VPC) is an isolated network that provides higher security and higher performance than the classic network.
For more information, see What is a VPC?
Zones are the physical locations that are provided with independent power supplies and networks in a region. Zones in the same region provide the same services.