Minor changes for implicit prefix lengths in Doltgres

sql/analyzer/validate_create_table.go

@@ -258,7 +258,7 @@ func resolveAlterColumn(ctx *sql.Context, a *Analyzer, n sql.Node, scope *plan.S
 				return nil, transform.SameTree, err
 			}
 
-			sch, err = validateAddColumn(initialSch, sch, n.(*plan.AddColumn))
+			sch, err = ValidateAddColumn(sch, n.(*plan.AddColumn))
 			if err != nil {
 				return nil, transform.SameTree, err
 			}
@@ -395,7 +395,10 @@ func validateRenameColumn(initialSch, sch sql.Schema, rc *plan.RenameColumn) (sq
 	return renameInSchema(sch, rc.ColumnName, rc.NewColumnName, nameable.Name()), nil
 }
 
-func validateAddColumn(initialSch sql.Schema, schema sql.Schema, ac *plan.AddColumn) (sql.Schema, error) {
+// ValidateAddColumn validates that the column specified in |ac| can be added to the specified
+// |schema|. A new Schema is returned, with the added column, if the column can be added. Otherwise,
+// an error is returned if there are any validation errors.
+func ValidateAddColumn(schema sql.Schema, ac *plan.AddColumn) (sql.Schema, error) {
 	table := ac.Table
 	nameable := table.(sql.Nameable)
 
@@ -828,8 +831,6 @@ func validateAutoIncrementAdd(schema sql.Schema, keyColumns map[string]bool) err
 	return nil
 }
 
-const textIndexPrefix = 1000
-
 func schToColMap(sch sql.Schema) map[string]*sql.Column {
 	colMap := make(map[string]*sql.Column, len(sch))
 	for _, col := range sch {

sql/plan/alter_index.go

@@ -138,6 +138,11 @@ func (p AlterIndex) WithChildren(children ...sql.Node) (sql.Node, error) {
 	}
 }
 
+func (p AlterIndex) WithColumns(columns []sql.IndexColumn) (sql.Node, error) {
+	p.Columns = columns
+	return &p, nil
+}
+
 func (p AlterIndex) WithTargetSchema(schema sql.Schema) (sql.Node, error) {
 	p.targetSchema = schema
 	return &p, nil

sql/plan/ddl.go

@@ -133,6 +133,14 @@ func (c *CreateTable) WithDatabase(db sql.Database) (sql.Node, error) {
 	return &nc, nil
 }
 
+// WithIndexDefs returns a copy of this CreateTable instance, with the index definitions
+// set to |idxDefs|.
+func (c *CreateTable) WithIndexDefs(idxDefs sql.IndexDefs) (*CreateTable, error) {
+	nc := *c
+	nc.idxDefs = idxDefs
+	return &nc, nil
+}
+
 // Name implements the Nameable interface.
 func (c *CreateTable) Name() string {
 	return c.name