Is the real database data of TiDB stored in kv and pd?

Is the real database data of TiDB stored in kv and pd?

---

Other Answer 1:

Data are stored in TiKV

Other Answer 2:

• TiDB Server: The SQL layer, which exposes the connection endpoint of the MySQL protocol, is responsible for accepting connections from clients, performing SQL parsing and optimization, and finally generating a distributed execution plan.The TiDB layer itself is stateless. In practice, multiple TiDB instances can be started, and a unified access address is provided externally through load balancing components (such as LVS, HAProxy or F5), and client connections can be evenly distributed among multiple TiDB instances.In order to achieve the effect of load balancing.TiDB Server itself does not store data, but only parses SQL and forwards the actual data read request to the underlying storage node TiKV (or TiFlash).
• PD (Placement Driver) Server: The meta information management module of the entire TiDB cluster, responsible for storing the real-time data distribution of each TiKV node and the overall topology of the cluster, and providing the TiDB Dashboard management and control interface.And assign a transaction ID to the distributed transaction.PD not only stores meta information, but also issues data scheduling commands to specific TiKV nodes according to the real-time data distribution status reported by TiKV nodes, which can be said to be the "brain" of the entire cluster.In addition, the PD itself is also composed of at least 3 nodes and has high availability capabilities.It is recommended to deploy an odd number of PD nodes.
• Storage Nodes
  • TiKV Server: Responsible for storing data. From the outside, TiKV is a distributed Key-Value storage engine that provides transactions.The basic unit for storing data is Region. Each Region is responsible for storing the data of a Key Range (the left-closed and right-open interval from StartKey to EndKey). Each TiKV node is responsible for multiple Regions.TiKV's API provides native support for distributed transactions at the KV key-value pair level, and provides the SI (Snapshot Isolation) isolation level by default, which is also the core of TiDB's support for distributed transactions at the SQL level.After the SQL layer of TiDB completes the SQL parsing, it will convert the SQL execution plan into the actual call to the TiKV API.Therefore, the data is stored in TiKV.In addition, data in TiKV will automatically maintain multiple copies (the default is three copies), which naturally supports high availability and automatic failover.
  • TiFlash: TiFlash is a special type of storage node.Unlike ordinary TiKV nodes, in TiFlash, data is stored in columnar form, and the main function is to accelerate analysis-based scenarios.

Other Answer 3:

Tidb data is stored on tikv.

tidb has three main components:

pd: It is the management module of the entire cluster. It has three main tasks: one is to store the meta information of the cluster (which TiKV node a key is stored in); the other is to schedule and load balance the TiKV cluster (such as dataMigration, migration of Raft group leaders, etc.); the third is to assign a globally unique and incremental transaction ID.

tidb: Responsible for receiving SQL requests, processing SQL-related logic, and finding the TiKV address for storing the data required for calculation through PD, interacting with TiKV to obtain data, and finally returning the result.TiDB Server is stateless, it does not store data itself, it is only responsible for computing, and can be scaled infinitely horizontally.

tikv: Responsible for storing data. From the outside, TiKV is a distributed Key-Value storage engine that provides transactions.The basic unit of data storage is Region. Each Region is responsible for storing data of a Key Range (the left-closed and right-open interval from StartKey to EndKey). Each TiKV node is responsible for multiple Regions.TiKV uses the Raft protocol for replication to maintain data consistency and disaster tolerance.

Other Answer 4:

TIKV

PD is a coordinated association