diff --git a/br/br-log-architecture.md b/br/br-log-architecture.md index a25990fa073b..580fed00cc42 100644 --- a/br/br-log-architecture.md +++ b/br/br-log-architecture.md @@ -17,7 +17,35 @@ summary: 了解 TiDB 的日志备份与 PITR 的架构设计。 日志备份的流程如下： -![BR log backup process design](/media/br/br-log-backup-ts.png) +```mermaid +sequenceDiagram + actor User + participant BR + participant PD + participant TiKV + participant TiDB + participant Storage + + User->>BR: Run `br log start` + BR->>PD: Register log backup task + TiKV->>PD: Fetch log backup task + par TiKV handles the local log backup task + loop + TiKV->>TiKV: Read KV change data + TiKV->>PD: Fetch global checkpoint ts + TiKV->>TiKV: Generate local metadata + TiKV->>Storage: Upload log data & metadata + TiKV->>PD: Configure GC + end + and + loop + TiDB->>TiKV: Watch backup progress + TiDB->>PD: Report global checkpoint ts + end + end + User->>BR: Run `br log status` + BR->>PD: Fetch status of log backup task +``` 系统组件和关键概念： @@ -53,7 +81,29 @@ summary: 了解 TiDB 的日志备份与 PITR 的架构设计。 PITR 的流程如下： -![Point-in-time recovery process design](/media/br/pitr-ts.png) +```mermaid +sequenceDiagram + actor User + participant BR + participant TiKV + participant PD + participant Storage + + User->>BR: Run `br restore point` + BR->>TiKV: Restore full data + loop restore log data + BR->>Storage: Read backup data + BR->>PD: Fetch Region info + BR->>TiKV: Request TiKV to restore data + loop TiKV handles restore request + TiKV->>Storage: Download KVs + TiKV->>TiKV: Rewrite KVs + TiKV->>TiKV: Apply KVs + end + TiKV->>BR: Report restore result + BR->>BR: Handle all restore results + end +``` 完整的 PITR 交互流程描述如下： diff --git a/br/br-snapshot-architecture.md b/br/br-snapshot-architecture.md index 800a8e34ab1e..6e8c6b7a030c 100644 --- a/br/br-snapshot-architecture.md +++ b/br/br-snapshot-architecture.md @@ -17,7 +17,28 @@ summary: 了解 TiDB 快照备份与恢复功能的架构设计。 集群快照数据备份的流程如下： -![snapshot backup process design](/media/br/br-snapshot-backup-ts.png) +```mermaid +sequenceDiagram + actor User + participant BR + participant PD + participant TiKV + participant Storage + + User->>BR: Run `br backup full` + BR->>PD: Pause GC + BR->>PD: Fetch TiKV and Region info + BR->>TiKV: Request TiKV to back up data + loop TiKV handles the local snapshot backup task + TiKV->>TiKV: Scan KVs + TiKV->>TiKV: Generate SST + TiKV->>Storage: Upload SST + end + TiKV->>BR: Report backup result + BR->>BR: Handle all backup results + BR->>TiKV: Back up schemas + BR->>Storage: Upload backup metadata +``` 完整的备份交互流程描述如下： @@ -49,7 +70,27 @@ summary: 了解 TiDB 快照备份与恢复功能的架构设计。 恢复集群快照备份数据的流程如下： -![snapshot restore process design](/media/br/br-snapshot-restore-ts.png) +```mermaid +sequenceDiagram + actor User + participant BR + participant PD + participant TiKV + participant Storage + + User->>BR: Run `br restore` + BR->>PD: Pause Region schedule + BR->>TiKV: Restore schema + BR->>PD: Split and scatter Regions + BR->>TiKV: Request TiKV to restore data + loop TiKV handles restore request + TiKV->>Storage: Download SST + TiKV->>TiKV: Rewrite KVs + TiKV->>TiKV: Ingest SST + end + TiKV->>BR: Report restore result + BR->>BR: Handle all restore results +``` 完整的恢复交互流程描述如下： diff --git a/dm/feature-shard-merge-pessimistic.md b/dm/feature-shard-merge-pessimistic.md index aacb2ef1cf16..a0744b9967b6 100644 --- a/dm/feature-shard-merge-pessimistic.md +++ b/dm/feature-shard-merge-pessimistic.md @@ -78,7 +78,35 @@ DM 在悲观模式下进行分表 DDL 的迁移有以下几点使用限制： 基于上述例子，本部分介绍了 DM 在默认的悲观模式下合库合表过程中进行 DDL 迁移的实现原理。 -![shard-ddl-flow](/media/dm/shard-ddl-flow.png) +```mermaid +--- +config: + themeCSS: | + /* hide the ugly borders */ + rect.rect { + stroke: none; + } +--- +sequenceDiagram + autonumber + box rgba(0,255,0,0.08) + participant Worker1 as DM-worker 1 + end + box rgba(255,255,0,0.08) + participant Master as DM-master + end + box rgba(0,255,0,0.08) + participant Worker2 as DM-worker 2 + end + + Worker1->>Master: 1. DDL info + Master->>Worker1: 2. DDL lock info + Worker2->>Master: 3. DDL info + Master->>Worker2: 4. DDL lock info + Master->>Worker1: 5. DDL execute request + Worker1->>Master: 6. DDL executed + Master-->>Worker2: 7. DDL ignore request +``` 在这个例子中，DM-worker-1 负责迁移来自 MySQL 实例 1 的数据，DM-worker-2 负责迁移来自 MySQL 实例 2 的数据，DM-master 负责协调多个 DM-worker 间的 DDL 迁移。 diff --git a/pessimistic-transaction.md b/pessimistic-transaction.md index 5ca5c8242be9..f40661184665 100644 --- a/pessimistic-transaction.md +++ b/pessimistic-transaction.md @@ -142,7 +142,39 @@ TiDB 在悲观事务模式下支持了 2 种隔离级别： TiDB 悲观锁复用了乐观锁的两阶段提交逻辑，重点在 DML 执行时做了改造。 -![TiDB 悲观事务的提交流程](/media/pessimistic-transaction-commit.png) +```mermaid +--- +config: + themeCSS: | + /* workaround for https://github.com/mermaid-js/mermaid/issues/523 */ + /* mark the two "Lock" arrows as red, by restyling the dashed arrows */ + line.messageLine1 { + stroke: #d32f2f; + stroke-dasharray: none !important; + } + /* make sure the arrow heads inherit the stroke color (another bug in mermaid) */ + #arrowhead path { + fill: context-stroke; + stroke: context-stroke; + } +--- +sequenceDiagram + participant Client + participant TiDB + participant TiKV + + Client->>TiDB: BEGIN + rect rgba(255, 0, 0, 0.08) + Client->>TiDB: DML + TiDB-->>TiKV: Lock + TiDB-->>TiKV: Lock + end + rect rgba(0, 0, 0, 0.04) + Client->>TiDB: COMMIT + TiDB->>TiKV: Prewrite + TiDB->>TiKV: Commit + end +``` 在两阶段提交之前增加了 Acquire Pessimistic Lock 阶段，简要步骤如下。 @@ -150,7 +182,52 @@ TiDB 悲观锁复用了乐观锁的两阶段提交逻辑，重点在 DML 执行 2. TiDB 收到来自客户端的更新数据的请求：TiDB 向 TiKV 发起加悲观锁请求，该锁持久化到 TiKV。 3. （同乐观锁）客户端发起 commit，TiDB 开始执行与乐观锁一样的两阶段提交。 -![TiDB 中的悲观事务](/media/pessimistic-transaction-in-tidb.png) +```mermaid +--- +title: Pessimistic Transaction in TiDB +--- +sequenceDiagram + participant client + participant TiDB + participant PD + participant TiKV + + client->>TiDB: begin + TiDB->>PD: get ts as start_ts + loop execute SQL + rect rgba(0, 0, 0, 0.04) + alt do read + TiDB->>TiKV: get data from TiKV with start_ts + TiDB->>client: return read result + else do write + rect rgba(255, 0, 0, 0.08) + loop if has write conflict + TiDB->>PD: get ts as for_update_ts + TiDB->>TiDB: write in cache + TiDB->>TiKV: acquire pessimistic locks parallelly + end + end + TiDB->>client: return write result + end + end + end + client->>TiDB: commit + opt start 2PC + rect rgba(0, 0, 0, 0.04) + par prewrite + TiDB->>TiKV: prewrite each key in cache with start_ts parallelly + end + end + rect rgba(0, 0, 0, 0.04) + par commit + TiDB->>PD: get ts as commit_ts + TiDB->>TiKV: commit primary_key with commit_ts first + TiDB->>client: success + TiDB->>TiKV: commit each secondary_key with commit_ts parallelly + end + end + end +``` 相关细节本节不再赘述，详情可阅读 [TiDB 悲观锁实现原理](https://pingkai.cn/tidbcommunity/blog/7730ed79)。 @@ -164,7 +241,25 @@ TiDB 悲观锁复用了乐观锁的两阶段提交逻辑，重点在 DML 执行 如果业务逻辑依赖加锁或等锁机制，或者即使在集群异常情况下也要尽可能保证事务提交的成功率，应关闭 pipelined 加锁功能。 -![Pipelined pessimistic lock](/media/pessimistic-transaction-pipelining.png) +```mermaid +--- +title: pipelined pessimistic lock +--- +sequenceDiagram + participant Client + participant TiDB + participant TiKV1 + participant TiKV2 + participant TiKV3 + + loop + Client->>TiDB: DML + TiDB->>TiKV1: Acquire pessimistic locks + TiKV1->>TiDB: OK + TiKV1--)TiKV2: Log replication + TiKV1--)TiKV3: Log replication + end +``` 该功能默认开启，可修改 TiKV 配置关闭：