1 Introduction
1.1 HTAP architectures
1.2 HTAP techniques
1.3 HTAP benchmarks
1.4 Contributions
2 Background of HTAP Databases
2.1 The Evolution of HTAP Databases
2.2 A Trade-off between Freshness and Isolation
3 HTAP Architectures
3.1 Primary Row Store+In-Memory Column Store
3.2 Distributed Row Store + Column Store Replica
3.3 Primary Row Store + Distributed IMCS
3.4 Primary Column Store+Delta Row Store
3.5 Applications of HTAP Architectures
3.6 Other Architectures
4 HTAP Techniques
4.1 Hybrid Workload Processing
4.2 Data Organization
4.3 Data Synchronization
4.4 Query Optimization
4.5 Resource Scheduling
5 HTAP Benchmarks
5.1 CH-Benchmark
5.2 HTAPBench
5.3 OLxPBench
5.4 HATtrick
5.5 HyBench
5.6 Micro-Benchmarks
6 Open Problems and Challenges
7 Conclusion