TiDB Roadamp

Roadmap：20190301
TiDB:
 Optimizer
 Statistics Optimization
 Multi-Column Statistics
 Cascades Planner
 Plan Management
 SQL Tuning Advisor
 Robust Access Path Selection: add the heuristic rule and improve the accuracy of index selection in OLTP scenarios
 Adaptive Query Optimization
 Execution Engine
 Parallel Operators
 Memory Control
 Concurrency Control
 Shuffle Operators
 Vectorized Expression Evaluation
 UDF
 SQL Features
 Support Views
 Support Window Functions
 Support Common Table Expressions
 Support Hash Partitioned Tables
 Support the utf8mb4_0900_ai_ci Collation
 Improve DDL
 Support Table Lock
 Support Change Column Type
 Support Multiple DDL Operations in a Single Statement
 Support Plugin System
 Support White List Plugin
 Support Audit Log Plugin
 Support RBAC Plugin
 Support Diagnostic Plugin
 Support Query Tracing
 Support Hybrid Column/Row-oriented Storage Engine
 Support New Storage Row Format: improve performance and reduce memory usage
 Support Non-integer Type of RowID
 Transaction
 Reduce Read-write Conflicts
 Optimize Transaction Scheduling Mechanism
 Refine Model and Reduce Latency
 Support Minimal Transaction (like the mini-transaction of InnoDB)
TiKV:
Raft
 Region Merge - Merge small Regions together to reduce overhead
 Local Read Thread - Process read requests in a local read thread
 Split Region in Batch - Speed up Region split for large Regions
 Raft Learner - Support Raft learner to smooth the configuration change process
 Raft Pre-vote - Support Raft pre-vote to avoid unnecessary leader election on network isolation
 Joint Consensus - Change multi members safely.
 Multi-thread Raftstore - Process Region Raft logic in multiple threads
 Multi-thread apply pool - Apply Region Raft committed entries in multiple threads
Engine
 Titan - Separate large key-values from LSM-Tree
 Pluggable Engine Interface - Clean up the engine wrapper code and provide more extensibility
Storage
 Flow Control - Do flow control in scheduler to avoid write stall in advance
Transaction
 Optimize transaction conflicts
 Distributed GC - Distribute MVCC garbage collection control to TiKV
Coprocessor
 Streaming - Cut large data set into small chunks to optimize memory consumption
 Chunk Execution - Process data in chunk to improve performance
 Request Tracing - Provide per-request execution details
Tools
 TiKV Importer - Speed up data importing by SST file ingestion
Client
 TiKV client (Rust crate)
 Batch gRPC Message - Reduce message overhead
PD:
 Improve namespace
 Different replication policies for different namespaces and tables
 Decentralize scheduling table Regions
 Scheduler supports prioritization to be more controllable
 Use machine learning to optimize scheduling
 Optimize Region metadata - Save Region metadata in detached storage engine
TiSpark:
 Limit/Order push-down
 Access through the DAG interface and deprecate the Select interface
 Index Join and parallel merge join
 Data Federation
Tools:
 Tool for automating TiDB deployment
 High-Performance data import tool (lightning)
 Backup and restore tool (incremental backup supported by drainer, incremental restore supported by reparo)
 New TiDB-binlog with improved architecture
 Data online migration tool (premium edition of Syncer)
 Diagnostic tools

参考：https://pingcap.com/docs/ROADMAP/