It is divided into the lexical parser and syntactic parser. SQL is first split into indivisible words through a lexical parser.

SQL Route

The sharding strategy configured by the user is matched according to the parsing context and the routing path is generated. Currently, sharding router and broadcast router are supported.

Rewrite SQL into statements that can be executed correctly in a real database. SQL rewriting is divided into rewriting for correctness and rewriting for optimization.

SQL Execution

It merges multiple execution result sets to achieve output through the unified JDBC interface. The result merger includes the stream merger, memory merger and appended merger using decorator mode.

Query Optimization

Supported by the experimental Federation Execution Engine, it optimizes complex queries such as associated queries and sub-queries and supports distributed queries across multiple database instances. It internally optimizes query plans using relational algebra to query results through optimal plans.