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

     1  /*
     2  Copyright 2019 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  	"vitess.io/vitess/go/vt/sqlparser"
    21  	"vitess.io/vitess/go/vt/vterrors"
    22  	"vitess.io/vitess/go/vt/vtgate/engine"
    23  	"vitess.io/vitess/go/vt/vtgate/planbuilder/plancontext"
    24  )
    25  
    26  // buildDeletePlan builds the instructions for a DELETE statement.
    27  func buildDeletePlan(string) stmtPlanner {
    28  	return func(stmt sqlparser.Statement, reservedVars *sqlparser.ReservedVars, vschema plancontext.VSchema) (*planResult, error) {
    29  		del := stmt.(*sqlparser.Delete)
    30  		if del.With != nil {
    31  			return nil, vterrors.VT12001("WITH expression in DELETE statement")
    32  		}
    33  		var err error
    34  		if len(del.TableExprs) == 1 && len(del.Targets) == 1 {
    35  			del, err = rewriteSingleTbl(del)
    36  			if err != nil {
    37  				return nil, err
    38  			}
    39  		}
    40  		dml, tables, ksidVindex, err := buildDMLPlan(vschema, "delete", del, reservedVars, del.TableExprs, del.Where, del.OrderBy, del.Limit, del.Comments, del.Targets)
    41  		if err != nil {
    42  			return nil, err
    43  		}
    44  		edel := &engine.Delete{DML: dml}
    45  		if dml.Opcode == engine.Unsharded {
    46  			return newPlanResult(edel, tables...), nil
    47  		}
    48  
    49  		if len(del.Targets) > 1 {
    50  			return nil, vterrors.VT12001("multi-table DELETE statement in a sharded keyspace")
    51  		}
    52  
    53  		edelTable, err := edel.GetSingleTable()
    54  		if err != nil {
    55  			return nil, err
    56  		}
    57  		if len(del.Targets) == 1 && del.Targets[0].Name != edelTable.Name {
    58  			return nil, vterrors.VT03003(del.Targets[0].Name.String())
    59  		}
    60  
    61  		if len(edelTable.Owned) > 0 {
    62  			aTblExpr, ok := del.TableExprs[0].(*sqlparser.AliasedTableExpr)
    63  			if !ok {
    64  				return nil, vterrors.VT12001("deleting from a complex table expression")
    65  			}
    66  			tblExpr := &sqlparser.AliasedTableExpr{Expr: sqlparser.TableName{Name: edelTable.Name}, As: aTblExpr.As}
    67  			edel.OwnedVindexQuery = generateDMLSubquery(tblExpr, del.Where, del.OrderBy, del.Limit, edelTable, ksidVindex.Columns)
    68  			edel.KsidVindex = ksidVindex.Vindex
    69  			edel.KsidLength = len(ksidVindex.Columns)
    70  		}
    71  
    72  		return newPlanResult(edel, tables...), nil
    73  	}
    74  }
    75  
    76  func rewriteSingleTbl(del *sqlparser.Delete) (*sqlparser.Delete, error) {
    77  	atExpr, ok := del.TableExprs[0].(*sqlparser.AliasedTableExpr)
    78  	if !ok {
    79  		return del, nil
    80  	}
    81  	if !atExpr.As.IsEmpty() && !sqlparser.Equals.IdentifierCS(del.Targets[0].Name, atExpr.As) {
    82  		// Unknown table in MULTI DELETE
    83  		return nil, vterrors.VT03003(del.Targets[0].Name.String())
    84  	}
    85  
    86  	tbl, ok := atExpr.Expr.(sqlparser.TableName)
    87  	if !ok {
    88  		// derived table
    89  		return nil, vterrors.VT03004(atExpr.As.String())
    90  	}
    91  	if atExpr.As.IsEmpty() && !sqlparser.Equals.IdentifierCS(del.Targets[0].Name, tbl.Name) {
    92  		// Unknown table in MULTI DELETE
    93  		return nil, vterrors.VT03003(del.Targets[0].Name.String())
    94  	}
    95  
    96  	del.TableExprs = sqlparser.TableExprs{&sqlparser.AliasedTableExpr{Expr: tbl}}
    97  	del.Targets = nil
    98  	if del.Where != nil {
    99  		_ = sqlparser.Walk(func(node sqlparser.SQLNode) (kontinue bool, err error) {
   100  			col, ok := node.(*sqlparser.ColName)
   101  			if !ok {
   102  				return true, nil
   103  			}
   104  			if !col.Qualifier.IsEmpty() {
   105  				col.Qualifier = tbl
   106  			}
   107  			return true, nil
   108  		}, del.Where)
   109  	}
   110  	return del, nil
   111  }