Local/Global Transaction in Cross-DC Deployment Tasklist

[JmPotato]

Development Task

Part of #18253, #20561, and tikv/pd#2759, in order to make TiDB support the Local/Global Transaction in Cross-DC Deployment, which further enables TiDB to support Cross-Region Deployment & Geo-Partition (#18273).

• RFC: Local/Global Transaction in Cross-DC Deployment (In Chinese)
• Proposal: doc/design: add a proposal for the local transaction #20588 or Proposal: Support the Local/Global Transaction in Cross-DC Deployment

New feature

Basic Work

• Update the PD Client wrapper to support the new Local/Global TSO generation. store: update the PD client to support the Global/Local TSO #20980 @JmPotato
• Introduce the new DC location configuration. @Yisaer
• Add a new Session variable tidb_txn_scope to dispatch the Local/Global Transactions. variable: add txn_scope sys var #20721 @Yisaer
• Dispatch a transaction as local or global. *: dispatch the local and global transactions #21353 @JmPotato

Data Constraint Check

• Get the Placement Rule from DDL info. Provide API to obtain the DC information of partitions #20911 (~1 day) @Yisaer
• Check the data constraint of a local transaction. Check the partition placement constraint of local transactions #20827 (~4 days) @Yisaer
• Check partition placement constraints when local transactions read data. Check partition placement constraints when local transactions read data #21426 (~4 days)
• Add a middle state in altering placement policies. Add a middle state in altering placement policies #21119 (~4 days) @Yisaer
• Check the scheme version changing. Abort the transaction when the placement rules are changed #20809 (~3 days) @Yisaer
• Check the internal SQL. Start global transactions for some special SQLs #20853 (~4 days) @JmPotato
• Allocate local TSO for other modules. @JmPotato Allocate local TSO for other modules except for transactions #21452 (~1 day)
• Resolve the Async Commit/1PC conflicts. （ ref: Adapt async commit/1pc with multi data center tikv/sig-transaction#63 ）

Optional Work

• Record transaction scopes in statements summary and slow logs. Record transaction scopes in statements summary and slow query #20774 (~2 days)
• Provide a session variable to query the last transaction scope. Provide a session variable to query the last transaction scope #20775 （~1 day)

[Yisaer]

assign "Add a new Session variable tidb_txn_scope to dispatch the Local/Global Transactions." @Yisaer

[JmPotato]

assign "Update the PD Client wrapper to support the new Local/Global TSO generation." @JmPotato