OSPP 2024 project:
https://summer-ospp.ac.cn/org/prodetail/247410235?list=org&navpage=org
Solutions:
- parser (planparserv2)
- add CallExpr in planparserv2/Plan.g4
- update parser_visitor and show_visitor
- grpc protobuf
- add CallExpr in plan.proto
- execution (`core/src/exec`)
- add `CallExpr` `ValueExpr` and `ColumnExpr` (both logical and
physical) for function call and function parameters
- function factory (`core/src/exec/expression/function`)
- create a global hashmap when starting milvus (see server.go)
- the global hashmap stores function signatures and their function
pointers, the CallExpr in execution engine can get the function pointer
by function signature.
- custom functions
- empty(string)
- starts_with(string, string)
- add cpp/go unittests and E2E tests
closes: #36559
Signed-off-by: Yinzuo Jiang <jiangyinzuo@foxmail.com>
