vitess.io/vitess@v0.16.2/go/vt/vtgate/planbuilder/filtering.go (about)

     1  /*
     2  Copyright 2020 The Vitess Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package planbuilder
    18  
    19  import (
    20  	"fmt"
    21  
    22  	"vitess.io/vitess/go/vt/vtgate/evalengine"
    23  	"vitess.io/vitess/go/vt/vtgate/planbuilder/operators"
    24  	"vitess.io/vitess/go/vt/vtgate/semantics"
    25  
    26  	"vitess.io/vitess/go/vt/sqlparser"
    27  	"vitess.io/vitess/go/vt/vterrors"
    28  	"vitess.io/vitess/go/vt/vtgate/engine"
    29  )
    30  
    31  // planFilter solves this particular expression, either by pushing it down to a child or changing this logicalPlan
    32  func planFilter(pb *primitiveBuilder, input logicalPlan, filter sqlparser.Expr, whereType string, origin logicalPlan) (logicalPlan, error) {
    33  	switch node := input.(type) {
    34  	case *join:
    35  		isLeft := true
    36  		var in logicalPlan
    37  		if node.isOnLeft(origin.Order()) {
    38  			in = node.Left
    39  		} else {
    40  			if node.ejoin.Opcode == engine.LeftJoin {
    41  				return nil, vterrors.VT12001("cross-shard LEFT JOIN and WHERE clause")
    42  			}
    43  			isLeft = false
    44  			in = node.Right
    45  		}
    46  
    47  		filtered, err := planFilter(pb, in, filter, whereType, origin)
    48  		if err != nil {
    49  			return nil, err
    50  		}
    51  		if isLeft {
    52  			node.Left = filtered
    53  		} else {
    54  			node.Right = filtered
    55  		}
    56  		return node, nil
    57  
    58  	case *route:
    59  		sel := node.Select.(*sqlparser.Select)
    60  		switch whereType {
    61  		case sqlparser.WhereStr:
    62  			sel.AddWhere(filter)
    63  		case sqlparser.HavingStr:
    64  			sel.AddHaving(filter)
    65  		}
    66  		node.UpdatePlan(pb, filter)
    67  		return node, nil
    68  	case *pulloutSubquery:
    69  		plan, err := planFilter(pb, node.underlying, filter, whereType, origin)
    70  		if err != nil {
    71  			return nil, err
    72  		}
    73  		node.underlying = plan
    74  		return node, nil
    75  	case *vindexFunc:
    76  		return filterVindexFunc(node, filter)
    77  	case *simpleProjection:
    78  		return nil, vterrors.VT12001("filtering on results of cross-shard subquery")
    79  	case *orderedAggregate:
    80  		return nil, vterrors.VT12001("filtering on results of aggregates")
    81  	}
    82  
    83  	return nil, vterrors.VT13001(fmt.Sprintf("unreachable %T.filtering", input))
    84  }
    85  
    86  func filterVindexFunc(node *vindexFunc, filter sqlparser.Expr) (logicalPlan, error) {
    87  	if node.eVindexFunc.Opcode != engine.VindexNone {
    88  		return nil, vterrors.VT12001(operators.VindexUnsupported + " (multiple filters)")
    89  	}
    90  
    91  	// Check LHS.
    92  	comparison, ok := filter.(*sqlparser.ComparisonExpr)
    93  	if !ok {
    94  		return nil, vterrors.VT12001(operators.VindexUnsupported + " (not a comparison)")
    95  	}
    96  	if comparison.Operator != sqlparser.EqualOp && comparison.Operator != sqlparser.InOp {
    97  		return nil, vterrors.VT12001(operators.VindexUnsupported + " (not equality)")
    98  	}
    99  	colname, ok := comparison.Left.(*sqlparser.ColName)
   100  	if !ok {
   101  		return nil, vterrors.VT12001(operators.VindexUnsupported + " (lhs is not a column)")
   102  	}
   103  	if !colname.Name.EqualString("id") {
   104  		return nil, vterrors.VT12001(operators.VindexUnsupported + " (lhs is not id)")
   105  	}
   106  
   107  	// Check RHS.
   108  	// We have to check before calling NewPlanValue because NewPlanValue allows lists also.
   109  	if !sqlparser.IsValue(comparison.Right) && !sqlparser.IsSimpleTuple(comparison.Right) {
   110  		return nil, vterrors.VT12001(operators.VindexUnsupported + " (rhs is not a value)")
   111  	}
   112  	var err error
   113  	node.eVindexFunc.Value, err = evalengine.Translate(comparison.Right, semantics.EmptySemTable())
   114  	if err != nil {
   115  		return nil, vterrors.VT12001(fmt.Sprintf("%s: %v", operators.VindexUnsupported, err))
   116  	}
   117  
   118  	node.eVindexFunc.Opcode = engine.VindexMap
   119  	return node, nil
   120  }