implement if [not] exists logic for DDL around views and indexes (#3006)

Author: jycor

enginetest/queries/index_queries.go

@@ -4338,4 +4338,63 @@ var IndexQueries = []ScriptTest{
 			},
 		},
 	},
+	{
+		Name: "indexes and if exists",
+		SetUpScript: []string{
+			"create table t (i int, j int);",
+			"create index idx on t (i);",
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				Query:       "create index idx on t(j)",
+				ExpectedErr: sql.ErrDuplicateKey,
+			},
+			{
+				Query: "create index if not exists idx on t(j)",
+				Expected: []sql.Row{
+					{types.NewOkResult(0)},
+				},
+			},
+			{
+				Query: "show create table t",
+				Expected: []sql.Row{
+					{"t", "CREATE TABLE `t` (\n" +
+						"  `i` int,\n" +
+						"  `j` int,\n" +
+						"  KEY `idx` (`i`)\n" +
+						") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin"},
+				},
+			},
+			{
+				Query:       "alter table t add index idx (j)",
+				ExpectedErr: sql.ErrDuplicateKey,
+			},
+			{
+				Query: "alter table t add index if not exists idx (j)",
+				Expected: []sql.Row{
+					{types.NewOkResult(0)},
+				},
+			},
+			{
+				Query: "show create table t",
+				Expected: []sql.Row{
+					{"t", "CREATE TABLE `t` (\n" +
+						"  `i` int,\n" +
+						"  `j` int,\n" +
+						"  KEY `idx` (`i`)\n" +
+						") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin"},
+				},
+			},
+			{
+				Query:       "alter table t drop index notanidx",
+				ExpectedErr: sql.ErrCantDropFieldOrKey,
+			},
+			{
+				Query: "alter table t drop index if exists notanidx",
+				Expected: []sql.Row{
+					{types.NewOkResult(0)},
+				},
+			},
+		},
+	},
 }

enginetest/queries/view_queries.go

@@ -20,6 +20,36 @@ import (
 )
 
 var ViewScripts = []ScriptTest{
+	{
+		Name: "existing views",
+		SetUpScript: []string{
+			"create view v as select 1;",
+			"create table t (i int);",
+			"insert into t values (1);",
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				Query: "create view if not exists v as select 2;",
+				Expected: []sql.Row{
+					{types.NewOkResult(0)},
+				},
+			},
+			{
+				Query:    "select * from v;",
+				Expected: []sql.Row{{1}},
+			},
+			{
+				Query: "create view if not exists t as select 2;",
+				Expected: []sql.Row{
+					{types.NewOkResult(0)},
+				},
+			},
+			{
+				Query:    "select * from t;",
+				Expected: []sql.Row{{1}},
+			},
+		},
+	},
 	{
 		Name: "multi database view",
 		SetUpScript: []string{

go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/dolthub/go-icu-regex v0.0.0-20250327004329-6799764f2dad
 	github.com/dolthub/jsonpath v0.0.2-0.20240227200619-19675ab05c71
 	github.com/dolthub/sqllogictest/go v0.0.0-20201107003712-816f3ae12d81
-	github.com/dolthub/vitess v0.0.0-20250604183723-cad71bbe21d0
+	github.com/dolthub/vitess v0.0.0-20250605180032-fa2a634c215b
 	github.com/go-kit/kit v0.10.0
 	github.com/go-sql-driver/mysql v1.7.2-0.20231213112541-0004702b931d
 	github.com/gocraft/dbr/v2 v2.7.2

go.sum

@@ -58,10 +58,8 @@ github.com/dolthub/jsonpath v0.0.2-0.20240227200619-19675ab05c71 h1:bMGS25NWAGTE
 github.com/dolthub/jsonpath v0.0.2-0.20240227200619-19675ab05c71/go.mod h1:2/2zjLQ/JOOSbbSboojeg+cAwcRV0fDLzIiWch/lhqI=
 github.com/dolthub/sqllogictest/go v0.0.0-20201107003712-816f3ae12d81 h1:7/v8q9XGFa6q5Ap4Z/OhNkAMBaK5YeuEzwJt+NZdhiE=
 github.com/dolthub/sqllogictest/go v0.0.0-20201107003712-816f3ae12d81/go.mod h1:siLfyv2c92W1eN/R4QqG/+RjjX5W2+gCTRjZxBjI3TY=
-github.com/dolthub/vitess v0.0.0-20250530231040-bfd522856394 h1:sMwntvk7O9dttaJLqnOvy8zgk0ah9qnyWkAahfOgnIo=
-github.com/dolthub/vitess v0.0.0-20250530231040-bfd522856394/go.mod h1:1gQZs/byeHLMSul3Lvl3MzioMtOW1je79QYGyi2fd70=
-github.com/dolthub/vitess v0.0.0-20250604183723-cad71bbe21d0 h1:esaEESlRNds2thjx9mEiDRIp1Cm5nM9K2PbYqPKei5Q=
-github.com/dolthub/vitess v0.0.0-20250604183723-cad71bbe21d0/go.mod h1:1gQZs/byeHLMSul3Lvl3MzioMtOW1je79QYGyi2fd70=
+github.com/dolthub/vitess v0.0.0-20250605180032-fa2a634c215b h1:rgZXgRYZ3SZbb4Tz5Y6vnzvB7P9pFvEP+Q7UGfRC9uY=
+github.com/dolthub/vitess v0.0.0-20250605180032-fa2a634c215b/go.mod h1:1gQZs/byeHLMSul3Lvl3MzioMtOW1je79QYGyi2fd70=
 github.com/dustin/go-humanize v0.0.0-20171111073723-bb3d318650d4/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
 github.com/eapache/go-resiliency v1.1.0/go.mod h1:kFI+JgMyC7bLPUVY133qvEBtVayf5mFgVsvEsIPBvNs=
 github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21/go.mod h1:+020luEh2TKB4/GOp8oxxtq0Daoen/Cii55CzbTV6DU=

memory/database.go

@@ -555,7 +555,7 @@ func (d *Database) Database() *BaseDatabase {
 func (d *Database) CreateView(ctx *sql.Context, name string, selectStatement, createViewStmt string) error {
 	_, ok := d.views[strings.ToLower(name)]
 	if ok {
-		return sql.ErrExistingView.New(name)
+		return sql.ErrExistingView.New(d.Name(), name)
 	}
 
 	sqlMode := sql.LoadSqlMode(ctx)

sql/analyzer/validate_create_table.go

@@ -657,6 +657,9 @@ func validateAlterIndex(ctx *sql.Context, initialSch, sch sql.Schema, ai *plan.A
 			}
 		}
 		if savedIdx == -1 {
+			if ai.IfExists {
+				return nil, nil
+			}
 			return nil, sql.ErrCantDropFieldOrKey.New(ai.IndexName)
 		}
 		// Remove the index from the list

sql/index_driver.go

@@ -120,7 +120,7 @@ var (
 	ErrIndexExpressionAlreadyRegistered = errors.NewKind("there is already an index registered for the expressions: %s")
 
 	// ErrIndexNotFound is returned when the index could not be found.
-	ErrIndexNotFound = errors.NewKind("index %q	was not found")
+	ErrIndexNotFound = errors.NewKind("index %q was not found")
 
 	// ErrIndexDeleteInvalidStatus is returned when the index trying to delete
 	// does not have a ready or outdated state.

sql/plan/alter_index.go

@@ -45,9 +45,13 @@ type AlterIndex struct {
 	// Action states whether it's a CREATE, DROP, or RENAME
 	Action IndexAction
 	// ddlNode references to the database that is being operated on
-	ddlNode
+	Db sql.Database
 	// Table is the table that is being referenced
 	Table sql.TableNode
+	// IfExists indicates if we should error when deleting an index that doesn't exist
+	IfExists bool
+	// IfNotExists indicates if we should error when creating a duplicate index
+	IfNotExists bool
 	// IndexName is the index name, and in the case of a RENAME it represents the new name
 	IndexName string
 	// PreviousIndexName states the old name when renaming an index
@@ -72,32 +76,34 @@ var _ sql.Expressioner = (*AlterIndex)(nil)
 var _ sql.Node = (*AlterIndex)(nil)
 var _ sql.CollationCoercible = (*AlterIndex)(nil)
 
-func NewAlterCreateIndex(db sql.Database, table sql.TableNode, indexName string, using sql.IndexUsing, constraint sql.IndexConstraint, columns []sql.IndexColumn, comment string) *AlterIndex {
+func NewAlterCreateIndex(db sql.Database, table sql.TableNode, ifNotExists bool, indexName string, using sql.IndexUsing, constraint sql.IndexConstraint, columns []sql.IndexColumn, comment string) *AlterIndex {
 	return &AlterIndex{
-		Action:     IndexAction_Create,
-		ddlNode:    ddlNode{Db: db},
-		Table:      table,
-		IndexName:  indexName,
-		Using:      using,
-		Constraint: constraint,
-		Columns:    columns,
-		Comment:    comment,
+		Action:      IndexAction_Create,
+		Db:          db,
+		Table:       table,
+		IfNotExists: ifNotExists,
+		IndexName:   indexName,
+		Using:       using,
+		Constraint:  constraint,
+		Columns:     columns,
+		Comment:     comment,
 	}
 }
 
-func NewAlterDropIndex(db sql.Database, table sql.TableNode, indexName string) *AlterIndex {
+func NewAlterDropIndex(db sql.Database, table sql.TableNode, ifExists bool, indexName string) *AlterIndex {
 	return &AlterIndex{
 		Action:    IndexAction_Drop,
-		ddlNode:   ddlNode{Db: db},
+		Db:        db,
 		Table:     table,
+		IfExists:  ifExists,
 		IndexName: indexName,
 	}
 }
 
 func NewAlterRenameIndex(db sql.Database, table sql.TableNode, fromIndexName, toIndexName string) *AlterIndex {
 	return &AlterIndex{
 		Action:            IndexAction_Rename,
-		ddlNode:           ddlNode{Db: db},
+		Db:                db,
 		Table:             table,
 		IndexName:         toIndexName,
 		PreviousIndexName: fromIndexName,
@@ -107,7 +113,7 @@ func NewAlterRenameIndex(db sql.Database, table sql.TableNode, fromIndexName, to
 func NewAlterDisableEnableKeys(db sql.Database, table sql.TableNode, disableKeys bool) *AlterIndex {
 	return &AlterIndex{
 		Action:      IndexAction_DisableEnableKeys,
-		ddlNode:     ddlNode{Db: db},
+		Db:          db,
 		Table:       table,
 		DisableKeys: disableKeys,
 	}
@@ -120,7 +126,7 @@ func (p *AlterIndex) Schema() sql.Schema {
 
 // WithChildren implements the Node interface. For AlterIndex, the only appropriate input is
 // a single child - The Table.
-func (p AlterIndex) WithChildren(children ...sql.Node) (sql.Node, error) {
+func (p *AlterIndex) WithChildren(children ...sql.Node) (sql.Node, error) {
 	if len(children) != 1 {
 		return nil, sql.ErrInvalidChildrenNumber.New(p, len(children), 1)
 	}
@@ -131,21 +137,24 @@ func (p AlterIndex) WithChildren(children ...sql.Node) (sql.Node, error) {
 	}
 	switch p.Action {
 	case IndexAction_Create, IndexAction_Drop, IndexAction_Rename, IndexAction_DisableEnableKeys:
-		p.Table = child
-		return &p, nil
+		np := *p
+		np.Table = child
+		return &np, nil
 	default:
 		return nil, ErrIndexActionNotImplemented.New(p.Action)
 	}
 }
 
-func (p AlterIndex) WithColumns(columns []sql.IndexColumn) (sql.Node, error) {
-	p.Columns = columns
-	return &p, nil
+func (p *AlterIndex) WithColumns(columns []sql.IndexColumn) (sql.Node, error) {
+	np := *p
+	np.Columns = columns
+	return &np, nil
 }
 
-func (p AlterIndex) WithTargetSchema(schema sql.Schema) (sql.Node, error) {
-	p.targetSchema = schema
-	return &p, nil
+func (p *AlterIndex) WithTargetSchema(schema sql.Schema) (sql.Node, error) {
+	np := *p
+	np.targetSchema = schema
+	return &np, nil
 }
 
 func (p *AlterIndex) TargetSchema() sql.Schema {
@@ -164,7 +173,7 @@ func (p *AlterIndex) Expressions() []sql.Expression {
 
 // WithExpressions implements the Node Interface. For AlterIndex, expressions represent  column defaults on the
 // targetSchema instance - required to be the same number of columns on the target schema.
-func (p AlterIndex) WithExpressions(expressions ...sql.Expression) (sql.Node, error) {
+func (p *AlterIndex) WithExpressions(expressions ...sql.Expression) (sql.Node, error) {
 	columns := p.TargetSchema().Copy()
 
 	if len(columns) != len(expressions) {
@@ -209,7 +218,7 @@ func (p *AlterIndex) WithDatabase(database sql.Database) (sql.Node, error) {
 	return &np, nil
 }
 
-func (p AlterIndex) String() string {
+func (p *AlterIndex) String() string {
 	pr := sql.NewTreePrinter()
 	switch p.Action {
 	case IndexAction_Create:
@@ -259,7 +268,7 @@ func (p AlterIndex) String() string {
 }
 
 func (p *AlterIndex) Resolved() bool {
-	return p.Table.Resolved() && p.ddlNode.Resolved() && p.targetSchema.Resolved()
+	return p.Table.Resolved() && p.targetSchema.Resolved()
 }
 
 func (p *AlterIndex) IsReadOnly() bool {

sql/plan/create_view.go

@@ -31,6 +31,7 @@ type CreateView struct {
 	database         sql.Database
 	targetSchema     sql.Schema
 	Name             string
+	IfNotExists      bool
 	IsReplace        bool
 	Definition       *SubqueryAlias
 	CreateViewString string
@@ -46,11 +47,12 @@ var _ sql.SchemaTarget = (*CreateView)(nil)
 
 // NewCreateView creates a CreateView node with the specified parameters,
 // setting its catalog to nil.
-func NewCreateView(database sql.Database, name string, definition *SubqueryAlias, isReplace bool, createViewStr, algorithm, definer, security string) *CreateView {
+func NewCreateView(database sql.Database, name string, definition *SubqueryAlias, ifNotExists, isReplace bool, createViewStr, algorithm, definer, security string) *CreateView {
 	return &CreateView{
 		UnaryNode:        UnaryNode{Child: definition},
 		database:         database,
 		Name:             name,
+		IfNotExists:      ifNotExists,
 		IsReplace:        isReplace,
 		Definition:       definition,
 		CreateViewString: createViewStr,

sql/planbuilder/create_ddl.go

@@ -672,7 +672,7 @@ func (b *Builder) buildCreateView(inScope *scope, subQuery string, fullQuery str
 	if !ok {
 		b.handleErr(sql.ErrDatabaseSchemaNotFound.New(c.Table.SchemaQualifier.String()))
 	}
-	createView := plan.NewCreateView(db, c.ViewSpec.ViewName.Name.String(), queryAlias, c.OrReplace, subQuery, c.ViewSpec.Algorithm, definer, c.ViewSpec.Security)
+	createView := plan.NewCreateView(db, c.ViewSpec.ViewName.Name.String(), queryAlias, c.IfNotExists, c.OrReplace, subQuery, c.ViewSpec.Algorithm, definer, c.ViewSpec.Security)
 	outScope.node = b.modifySchemaTarget(queryScope, createView, createView.Definition.Schema())
 
 	return outScope