2021-10-03 13:17:55 +00:00
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# Visitor Pattern
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Visitor Pattern is used in segcore for parse and execute Execution Plan.
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2021-10-04 00:26:32 +00:00
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1. Inside `${core}/src/query/PlanNode.h`, contains physical plan for vector search
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2021-10-03 13:17:55 +00:00
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1. `FloatVectorANNS` FloatVector search execution node
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2. `BinaryVectorANNS` BinaryVector search execution node
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2021-10-04 00:26:32 +00:00
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2. `${core}/src/query/Expr.h` contains physical plan for scalar expression
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2021-10-03 13:17:55 +00:00
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1. `TermExpr` support operation like `col in [1, 2, 3]`
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2. `RangeExpr` support constant compare with data column like `a >= 5` `1 < b < 2`
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3. `CompareExpr` support compare with different columns, like `a < b`
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4. `LogicalBinaryExpr` support and/or
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5. `LogicalUnaryExpr` support not
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Currently , under `${core/query/visitors}` directory, there are following visitors
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1. `ShowPlanNodeVisitor` print PlanNode in json
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2. `ShowExprVisitor` Expr -> json
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3. `Verify...Visitor` validate ...
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4. `ExtractInfo...Visitor` extract info from... ，including involved_fields and else
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5. `ExecExprVisitor` Generate bitmask according to expression
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6. `ExecPlanNodeVistor` physical plan executor, for now only support ANNS node.
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