TiKV is the storage layer for , a distributed HTAP SQL database. So far,we have only explained how a distributed transactional Key-Value database isimplemented. However this is still far from serving a SQL database. We willexplore and cover the following things in this chapter:

Storing data in a distributed manner using TiKV only utilizes distributed I/Oresources, while the TiDB node that receives SQL query is still in charge ofprocessing all rows. We can go a step further by delegating some processingtasks into TiKV nodes. This way, we can utilize distributed CPU resources! Inthis section, we will take a look at these supported physical plan executorsso far in TiKV and see how they enable TiDB executing SQL queries in adistributed way.

Vectorization is a technique that performs computing over a batch of values.By introducing vectorization into the execution engine, we will achieve higherperformance. This section will introduce its theory and the architecture ofthe vectorized execution engine introduced in TiKV 3.0.