github.com/insionng/yougam@v0.0.0-20170714101924-2bc18d833463/libraries/pingcap/tidb/optimizer/optimizer.go (about)

     1  // Copyright 2015 PingCAP, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package optimizer
    15  
    16  import (
    17  	"github.com/insionng/yougam/libraries/juju/errors"
    18  	"github.com/insionng/yougam/libraries/pingcap/tidb/ast"
    19  	"github.com/insionng/yougam/libraries/pingcap/tidb/context"
    20  	"github.com/insionng/yougam/libraries/pingcap/tidb/infoschema"
    21  	"github.com/insionng/yougam/libraries/pingcap/tidb/mysql"
    22  	"github.com/insionng/yougam/libraries/pingcap/tidb/optimizer/plan"
    23  	"github.com/insionng/yougam/libraries/pingcap/tidb/terror"
    24  )
    25  
    26  // Optimize does optimization and creates a Plan.
    27  // The node must be prepared first.
    28  func Optimize(ctx context.Context, node ast.Node, sb plan.SubQueryBuilder) (plan.Plan, error) {
    29  	// We have to infer type again because after parameter is set, the expression type may change.
    30  	if err := InferType(node); err != nil {
    31  		return nil, errors.Trace(err)
    32  	}
    33  	if err := logicOptimize(ctx, node); err != nil {
    34  		return nil, errors.Trace(err)
    35  	}
    36  	p, err := plan.BuildPlan(node, sb)
    37  	if err != nil {
    38  		return nil, errors.Trace(err)
    39  	}
    40  	if plan.UseNewPlanner {
    41  		_, err = plan.PredicatePushDown(p, []ast.ExprNode{})
    42  		if err != nil {
    43  			return nil, errors.Trace(err)
    44  		}
    45  	}
    46  	err = plan.Refine(p)
    47  	if err != nil {
    48  		return nil, errors.Trace(err)
    49  	}
    50  	return p, nil
    51  }
    52  
    53  // Prepare prepares a raw statement parsed from parser.
    54  // The statement must be prepared before it can be passed to optimize function.
    55  // We pass InfoSchema instead of getting from Context in case it is changed after resolving name.
    56  func Prepare(is infoschema.InfoSchema, ctx context.Context, node ast.Node) error {
    57  	ast.SetFlag(node)
    58  	if err := Preprocess(node, is, ctx); err != nil {
    59  		return errors.Trace(err)
    60  	}
    61  	if err := Validate(node, true); err != nil {
    62  		return errors.Trace(err)
    63  	}
    64  	return nil
    65  }
    66  
    67  // Optimizer error codes.
    68  const (
    69  	CodeOneColumn           terror.ErrCode = 1
    70  	CodeSameColumns         terror.ErrCode = 2
    71  	CodeMultiWildCard       terror.ErrCode = 3
    72  	CodeUnsupported         terror.ErrCode = 4
    73  	CodeInvalidGroupFuncUse terror.ErrCode = 5
    74  	CodeIllegalReference    terror.ErrCode = 6
    75  )
    76  
    77  // Optimizer base errors.
    78  var (
    79  	ErrOneColumn           = terror.ClassOptimizer.New(CodeOneColumn, "Operand should contain 1 column(s)")
    80  	ErrSameColumns         = terror.ClassOptimizer.New(CodeSameColumns, "Operands should contain same columns")
    81  	ErrMultiWildCard       = terror.ClassOptimizer.New(CodeMultiWildCard, "wildcard field exist more than once")
    82  	ErrUnSupported         = terror.ClassOptimizer.New(CodeUnsupported, "unsupported")
    83  	ErrInvalidGroupFuncUse = terror.ClassOptimizer.New(CodeInvalidGroupFuncUse, "Invalid use of group function")
    84  	ErrIllegalReference    = terror.ClassOptimizer.New(CodeIllegalReference, "Illegal reference")
    85  )
    86  
    87  func init() {
    88  	mySQLErrCodes := map[terror.ErrCode]uint16{
    89  		CodeOneColumn:           mysql.ErrOperandColumns,
    90  		CodeSameColumns:         mysql.ErrOperandColumns,
    91  		CodeMultiWildCard:       mysql.ErrParse,
    92  		CodeInvalidGroupFuncUse: mysql.ErrInvalidGroupFuncUse,
    93  		CodeIllegalReference:    mysql.ErrIllegalReference,
    94  	}
    95  	terror.ErrClassToMySQLCodes[terror.ClassOptimizer] = mySQLErrCodes
    96  }