[TODO]Support hints in goalisa

[weiguoz]

In the issue: 2220, we plan to supports Maxcompute hints.
goalisa is one of the dabase/sql driver of Maxcompute. We're going to support Maxcompute hints in goalisa at first.
I found our parser is able to split the hints from a SQL program. What we want to do are:

• To support passing the hints to the backend of the database, we need to implement interfaces DB.PrepareContext to prepare a stmt, then get the result via stmt.QueryContext(stmt.ExecContext).
  Moreover, we need to implement such methods in all database/sql drivers: goalisa/gomaxcompute/gohive to unify the code in SQLFlow.

  • gomaxcompute
  • gohive
  • goalisa

• Extract the hints from the parse result, and the hints will be sent to the goalisa finally via runSingleSQLFlowStatement
  

  sqlflow/pkg/sql/executor_ir.go

  Lines 105 to 124 in ddb63ce

  	func runSQLProgram(wr *pipe.Writer, sqlProgram string, db *database.DB, modelDir string, session *pb.Session) error {
  	stmts, err := parser.Parse(db.DriverName, sqlProgram)
  	if err != nil {
  	return err
  	}
  	// NOTE(tony): We generate IR and execute its translated program one-by-one since IR generation may depend on the execution
  	// of the previous statement. For example, consider a SQL program
  	//
  	// create table some_table as (select ...);
  	// select * from some_table to train ...
  	//
  	// The IR generation on the second statement would fail since it requires inspection the schema of some_table,
  	// which depends on the execution of create table some_table as (select ...);.
  	for _, sql := range stmts {
  	if err := runSingleSQLFlowStatement(wr, sql, db, modelDir, session); err != nil {
  	return err
  	}
  	}
  	return nil
  	}