glossary: Add more abbreviations

glossary.md

@@ -30,6 +30,10 @@
 
 Baseline Capturing captures queries that meet capturing conditions and create bindings for them. It is used for [preventing regression of execution plans during an upgrade](/sql-plan-management.md#prevent-regression-of-execution-plans-during-an-upgrade).
 
+### BR
+
+BR is the Backup and Restore tool for TiDB. See [BR Overview](/br/backup-and-restore-overview.md) for more information.
+
 ### Bucket
 
 A [Region](#regionpeerraft-group) is logically divided into several small ranges called bucket. TiKV collects query statistics by buckets and reports the bucket status to PD. For details, see the [Bucket design doc](https://github.com/tikv/rfcs/blob/master/text/0082-dynamic-size-region.md#bucket).
@@ -40,6 +44,10 @@
 
 With the cached table feature, TiDB loads the data of an entire table into the memory of the TiDB server, and TiDB directly gets the table data from the memory without accessing TiKV, which improves the read performance.
 
+### CF
+
+CF is short for Column Family as used by RocksDB / TiKV.
+
 ### Coalesce Partition
 
 Coalesce Partition is a way of decreasing the number of partitions in a Hash or Key partitioned table. For more information, see [Manage Hash and Key partitions](/partitioned-table.md#manage-hash-and-key-partitions).
@@ -48,14 +56,72 @@
 
 Introduced in TiDB 5.3.0, Continuous Profiling is a way to observe resource overhead at the system call level. With the support of Continuous Profiling, TiDB provides performance insight as clear as directly looking into the database source code, and helps R&D and operation and maintenance personnel to locate the root cause of performance problems using a flame graph. For details, see [TiDB Dashboard Instance Profiling - Continuous Profiling](/dashboard/continuous-profiling.md).
 
+### CTE
+
+A Common Table Expression (CTE) is part of the SQL standard and uses [`WITH`](/sql-statements/sql-statement-with.md) statements.
+
 ## D
 
+### DDL
+
+Data Definition Language (DDL) is the part of the SQL standard that deals with creating, modifying and deleting tables and other objects.
+
+### DM
+
+Data Migration is the tool that allows MySQL to TiDB migration by reading data from a source instance and applying it to a target MySQL instance. See [DM Overview](/dm/dm-overview.md) for more information.
+
+### DML
+
+Data Modification Language (DML) is the part of the SQL standard that deals with inserting, updating and deleting rows in tables.
+
+### DMR
+
+Development Milestone Release (DMR) is a version of TiDB that provides users with the latest features but doesn't provide long term support. See [TiDB Versioning](/releases/versioning.md) for more information.
+
+### DR
+
+Disaster Recovery (DR) describes solutions that can be used to recover from a disaster in the future. This includes things like backups and standby clusters.
+
+### DXF
+
+Distributed eXecution Framework (DXF) is the framework used by TiDB to speedup index creation and data import by distributing tasks over all available resources. See [DXF Introduction](/tidb-distributed-execution-framework.md) for more details
+
 ### Dynamic Pruning
 
 Dynamic pruning mode is one of the modes that TiDB accesses partitioned tables. In dynamic pruning mode, each operator supports direct access to multiple partitions. Therefore, TiDB no longer uses Union. Omitting the Union operation can improve the execution efficiency and avoid the problem of Union concurrent execution.
 
+## E
+
+### EC2
+
+Elastic Compute Cloud (EC2) is an AWS service that provides compute resources. This can be used with TiUP to run a TiDB Cluster.
+
+## G
+
+### GA
+
+General Available (GA) is the first non-beta version of a software product.
+
+### GC
+
+Garbage Collection (GC) is the process to cleanup unused resources. See [GC](/garbage-collection-overview.md) for the GC process of TiKV.
+
+### GTID
+
+Global Transactions ID's (GTIDs) are used by recent MySQL versions to indicate what transactions have been replicated and which have not. This information can be used by DM.
+
+## H
+
+### HTAP
+
+Hybrid Transactional Analytical Process (HTAP) is a database feature that allows both OLTP and OLAP workloads on the same database. For TiDB the HTAP feature is provided by using both TiKV for row storage and TiFlash for columnar storeage. See [the definition of HTAP on the Gartner website](https://www.gartner.com/en/information-technology/glossary/htap-enabling-memory-computing-technologies) for more information.
+
 ## I
 
+### IMDS
+
+Instance Metadata Service (IMDS) is a AWS service that can be used to manage EC2 instances. See [Instance metadata](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html) for more information.
+
 ### Index Merge
 
 Index Merge is a method introduced in TiDB v4.0 to access tables. Using this method, the TiDB optimizer can use multiple indexes per table and merge the results returned by each index. In some scenarios, this method makes the query more efficient by avoiding full table scans. Since v5.4, Index Merge has become a GA feature.
@@ -64,8 +130,26 @@
 
 The in-memory pessimistic lock is a new feature introduced in TiDB v6.0.0. When this feature is enabled, pessimistic locks are usually stored in the memory of the Region leader only, and are not persisted to disk or replicated through Raft to other replicas. This feature can greatly reduce the overhead of acquiring pessimistic locks and improve the throughput of pessimistic transactions.
 
+## K
+
+### KMS
+
+Key Management Service (KMS) allows the storage and retrieval of secret keys in a secure way. Examples of this are the AWS KMS, GCP KMS and HashiCorp Vault. Various TiDB components can use this to manage the keys that are used for storage encryption and related services.
+
+### KV
+
+Key-Value (KV) is a way storing information that allows easy retrieval by specifiying the key. Multiple values can be stored under a single key by encoding them. TiKV is implementing this.
+
 ## L
 
+### LDAP
+
+Lightweight Directory Access Protocol (LDAP) is a standardized way of accessing a directory with information. This is often used to store information on accounts. This is used in TiDB by [LDAP authentication plugins](/security-compatibility-with-mysql.md#authentication-plugin-status).
+
+### LTS
+
+Long Term Support (LTS) are software versions that are considered stable and are supported for a long term. See [TiDB Versioning](/releases/versioning.md) for more details.
+
 ### leader/follower/learner
 
 Leader/Follower/Learner each corresponds to a role in a Raft group of [peers](#regionpeerraft-group). The leader services all client requests and replicates data to the followers. If the group leader fails, one of the followers will be elected as the new leader. Learners are non-voting followers that only serves in the process of replica addition.
@@ -82,10 +166,22 @@
 
 ## O
 
+### OLAP
+
+OnLine Analytical Processing (OLAP) are describing database workloads that mostly deal with analytical workloads like reporting. The characteristics of this is read heavy queries that process many rows.
+
 ### Old value
 
 The "original value" in the incremental change log output by TiCDC. You can specify whether the incremental change log output by TiCDC contains the "original value".
 
+### OLTP
+
+OnLine Transaction Processing (OLTP) are describing database workloads that mostly deal with transactioonal workloads like inserting, updating and deleting small sets of records.
+
+## OOM
+
+Out of Memory (OOM) is a situation where a system fails due to a a lack of available memory. See [Troubleshoot TiDB OOM Issues](/troubleshoot-tidb-oom.md) for more details.
+
 ### Operator
 
 An operator is a collection of actions that applies to a Region for scheduling purposes. Operators perform scheduling tasks such as "migrate the leader of Region 2 to Store 5" and "migrate replicas of Region 2 to Store 1, 4, 5".
@@ -111,10 +207,18 @@
 
 [Partitioning](/partitioned-table.md) refers to physically dividing a table into smaller table partitions, which can be done by partition methods such as RANGE, LIST, HASH, and KEY partitioning.
 
+### PD
+
+Placement Driver (PD) is an important component of the [TiDB Architecture](/tidb-architecture.md#placement-driver-pd-server) that is responsible to store metadata and run the [TSO](/tso.md) that hands out timestamps that are used for transactions. It also orchestrates the data placement on TiKV and runs the [TiDB Dashboard](/dashboard/dashboard-overview.md).
+
 ### pending/down
 
 "Pending" and "down" are two special states of a peer. Pending indicates that the Raft log of followers or learners is vastly different from that of leader. Followers in pending cannot be elected as leader. "Down" refers to a state that a peer ceases to respond to leader for a long time, which usually means the corresponding node is down or isolated from the network.
 
+### PiTR
+
+Point in Time Recovery (PiTR) is a database feature that allows the user to restore to a specific point in time (for example just before an accidental `DELETE` statement). See [TiDB Log Backup and PITR Architecture](/br/br-log-architecture.md) for more details.
+
 ### Point Get
 
 Point get means reading a single row of data by a unique index or primary index, the returned resultset is up to one row.
@@ -125,6 +229,10 @@
 
 ## Q
 
+### QPS
+
+Queries Per Second (QPS) is a performance metric of a database service.
+
 ### Quota Limiter
 
 Quota Limiter is an experimental feature introduced in TiDB v6.0.0. If the machine on which TiKV is deployed has limited resources, for example, with only 4v CPU and 16 G memory, and the foreground of TiKV processes too many read and write requests, the CPU resources used by the background are occupied to help process such requests, which affects the performance stability of TiKV. To avoid this situation, the [quota-related configuration items](/tikv-configuration-file.md#quota) can be set to limit the CPU resources to be used by the foreground.
@@ -135,6 +243,10 @@
 
 Raft Engine is an embedded persistent storage engine with a log-structured design. It is built for TiKV to store multi-Raft logs. Since v5.4, TiDB supports using Raft Engine as the log storage engine. For details, see [Raft Engine](/tikv-configuration-file.md#raft-engine).
 
+### RAG
+
+Retrieval-Augmented Generation (RAG). See [Vector Search Overview](/vector-search-overview.md#use-cases) for more details.
+
 ### Region/peer/Raft group
 
 Region is the minimal piece of data storage in TiKV, each representing a range of data (256 MiB by default). Each Region has three replicas by default. A replica of a Region is called a peer. Multiple peers of the same Region replicate data via the Raft consensus algorithm, so peers are also members of a Raft instance. TiKV uses Multi-Raft to manage data. That is, for each Region, there is a corresponding, isolated Raft group.
@@ -145,10 +257,18 @@
 
 The mechanism of Region split is to use one initial Region to cover the entire key space, and generate new Regions through splitting existing ones every time the size of the Region or the number of keys has reached a threshold.
 
-### restore
+### Restore
 
 Restore is the reverse of the backup operation. It is the process of bringing back the system to an earlier state by retrieving data from a prepared backup.
 
+### RPC
+
+Remote Procedure Call (RPC) is a way for software components to communicate. In a TiDB cluster gRPC standard is used for communication between TiKV and TiDB.
+
+### RU
+
+Request Unit (RU) is used in TiDB to describe the unit for the resource usage. This is used with [Resource Control](/tidb-resource-control.md) to manage resource usage.
+
 ## S
 
 ### scheduler
@@ -160,6 +280,10 @@
 - `hot-region-scheduler`: Balances the distribution of hot Regions
 - `evict-leader-{store-id}`: Evicts all leaders of a node (often used for rolling upgrades)
 
+### SST
+
+Static Sorted Table is the  store format of RocksDB.
+
 ### Store
 
 A store refers to the storage node in the TiKV cluster (an instance of `tikv-server`). Each store has a corresponding TiKV instance.
@@ -170,6 +294,20 @@
 
 Top SQL helps locate SQL queries that contribute to a high load of a TiDB or TiKV node in a specified time range. For details, see [Top SQL user document](/dashboard/top-sql.md).
 
+### TPS
+
+Transactions Per Second (TPS) is a performance metric of a database.
+
 ### TSO
 
 Because TiKV is a distributed storage system, it requires a global timing service, Timestamp Oracle (TSO), to assign a monotonically increasing timestamp. In TiKV, such a feature is provided by PD, and in Google [Spanner](http://static.googleusercontent.com/media/research.google.com/en//archive/spanner-osdi2012.pdf), this feature is provided by multiple atomic clocks and GPS. For details, see [TSO](/tso.md).
+
+## U
+
+### URI
+
+Uniform Resource Identifier (URI) is a uniform way of describing a resource. See [Uniform Resource Identifier](https://en.wikipedia.org/wiki/Uniform_Resource_Identifier) on Wikipedia for more information.
+
+### UUID
+
+Universally Unique Identifier (UUID) is a 128-bit (16 byte) generated ID that can be used to identify records in a database. See [UUID](/best-practices/uuid.md) for more information on how UUID's are used in TiDB.