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+- [事务](#事务)
+  - [事务分类](#事务分类)
+    - [扁平事务](#扁平事务)
+    - [带有保存点的扁平事务](#带有保存点的扁平事务)
+    - [链事务](#链事务)
+    - [嵌套事务](#嵌套事务)
+      - [savepoint和嵌套事务区别](#savepoint和嵌套事务区别)
+    - [分布式事务](#分布式事务)
+  - [事务实现](#事务实现)
+    - [redo](#redo)
+      - [redo log persists before transaction committed](#redo-log-persists-before-transaction-committed)
+      - [redo log和undo log比较](#redo-log和undo-log比较)
+      - [redo log和binlog的比较](#redo-log和binlog的比较)
+      - [innodb\_flush\_log\_at\_trx\_commit](#innodb_flush_log_at_trx_commit)
+      - [log block](#log-block)
+        - [block \& atomic](#block--atomic)
+        - [log block header](#log-block-header)
+          - [`LOG_BLOCK_HDR_NO`](#log_block_hdr_no)
+        - [`LOG_BLOCK_HDR_DATA_LEN`](#log_block_hdr_data_len)
+        - [`LOG_BLOCK_FIRST_REC_GROUP`](#log_block_first_rec_group)
+        - [`LOG_BLOCK_CHECKPOINT_NO`](#log_block_checkpoint_no)
+        - [log block tailer](#log-block-tailer)
+      - [log group](#log-group)
+        - [redo log buffer刷新到磁盘中的时机](#redo-log-buffer刷新到磁盘中的时机)
+        - [WAL](#wal)
+      - [redo log format](#redo-log-format)
+        - [redo log头部格式](#redo-log头部格式)
+      - [LSN](#lsn)
+        - [页LSN](#页lsn)
+        - [查看LSN](#查看lsn)
+      - [recovery](#recovery)
+    - [undo](#undo)
+      - [undo log和redo log差异](#undo-log和redo-log差异)
+      - [非锁定读](#非锁定读)
+      - [undo log的产生会伴随redo log的产生](#undo-log的产生会伴随redo-log的产生)
+      - [存储管理](#存储管理)
+        - [innodb\_undo\_directory](#innodb_undo_directory)
+        - [innodb\_rollback\_segments](#innodb_rollback_segments)
+        - [innodb\_undo\_tablespaces](#innodb_undo_tablespaces)
+        - [purge](#purge)
+        - [undo页的重用设计](#undo页的重用设计)
+      - [核心概念](#核心概念)
+        - [rollback segment](#rollback-segment)
+        - [undo slots](#undo-slots)
+        - [undo segment](#undo-segment)
+      - [undo log格式](#undo-log格式)
+        - [insert undo log](#insert-undo-log)
+        - [update undo log](#update-undo-log)
+    - [undo log组织形式](#undo-log组织形式)
+      - [undo log的逻辑组织方式](#undo-log的逻辑组织方式)
+        - [record versions](#record-versions)
+      - [物理组织方式](#物理组织方式)
+        - [undo segment](#undo-segment-1)
+        - [undo page header](#undo-page-header)
+        - [undo segment header](#undo-segment-header)
+        - [undo log storing](#undo-log-storing)
+      - [文件组织方式](#文件组织方式)
+        - [rollback segment](#rollback-segment-1)
+      - [内存组织方式](#内存组织方式)
+        - [undo::Tablespace](#undotablespace)
+        - [trx\_rseg\_t](#trx_rseg_t)
+        - [trx\_undo\_t](#trx_undo_t)
+      - [undo writing](#undo-writing)
+        - [undo record写入](#undo-record写入)
+      - [undo for rollback](#undo-for-rollback)
+      - [undo for mvcc](#undo-for-mvcc)
+        - [历史版本](#历史版本)
+    - [purge](#purge-1)
+      - [history](#history)
+        - [history的purge流程](#history的purge流程)
+        - [innodb\_purge\_batch\_size](#innodb_purge_batch_size)
+        - [innodb\_max\_purge\_lag](#innodb_max_purge_lag)
+        - [innodb\_max\_purge\_lag\_delay](#innodb_max_purge_lag_delay)
+    - [group commit](#group-commit)
+      - [binlog](#binlog)
+        - [replication \&\& point-in-time recovery](#replication--point-in-time-recovery)
+        - [binlog format](#binlog-format)
+      - [group commit](#group-commit-1)
+        - [group commit机制](#group-commit机制)
+        - [`binlog_order_commits`](#binlog_order_commits)
+        - [`binlog_max_flush_queue_time = microseconds`](#binlog_max_flush_queue_time--microseconds)
+        - [binlog details](#binlog-details)
+        - [sync the storage engine and binary log](#sync-the-storage-engine-and-binary-log)
+        - [prepare\_commit\_mutex](#prepare_commit_mutex)
+        - [binary log group commit](#binary-log-group-commit)
+    - [事务控制语句](#事务控制语句)
+      - [rollback](#rollback)
+      - [rollback to savepoint](#rollback-to-savepoint)
+    - [事务操作统计](#事务操作统计)
+    - [事务隔离级别](#事务隔离级别)
+    - [长事务](#长事务)
+
 # 事务
 ## 事务分类
 事务通常可分为如下类型：