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| |
| # 执行计划生成器 Planner |
| |
| * org.apache.iotdb.db.qp.Planner |
| |
| 将 SQL 解析出的语法树转化成逻辑计划，逻辑优化，物理计划。 |
| |
| ## SQL 解析 |
| |
| SQL 解析采用 Antlr4 |
| |
| * antlr/src/main/antlr4/org/apache/iotdb/db/qp/strategy/SqlBase.g4 |
| |
| `mvn clean compile -pl antlr` 之后生成代码位置：antlr/target/generated-sources/antlr4 |
| |
| ## 逻辑计划生成器 |
| |
| * org.apache.iotdb.db.qp.strategy.LogicalGenerator |
| |
| ## 逻辑计划优化器 |
| |
| 目前有三种逻辑计划优化器 |
| |
| * org.apache.iotdb.db.qp.strategy.optimizer.ConcatPathOptimizer |
| |
| 路径优化器，将 SQL 中的查询路径进行拼接，与 MManager 进行交互去掉通配符，进行路径检查。 |
| |
| * org.apache.iotdb.db.qp.strategy.optimizer.RemoveNotOptimizer |
| |
| 谓词去非优化器，将谓词逻辑中的非操作符去掉。 |
| |
| * org.apache.iotdb.db.qp.strategy.optimizer.DnfFilterOptimizer |
| |
| 将谓词转化为析取范式。 |
| |
| * org.apache.iotdb.db.qp.strategy.optimizer.MergeSingleFilterOptimizer |
| |
| 将相同路径的谓词逻辑合并。 |
| |
| ## 物理计划生成器 |
| |
| * org.apache.iotdb.db.qp.strategy.PhysicalGenerator |
| |
