ddl: check constraint name.

Fixes #66 and also check duplication.

ddl/ddl.go

@@ -19,6 +19,7 @@ package ddl
 
 import (
 	"encoding/json"
+	"fmt"
 	"strings"
 	"sync"
 
@@ -261,6 +262,37 @@ func checkDuplicateColumn(colDefs []*coldef.ColumnDef) error {
 	return nil
 }
 
+func checkConstraintNames(constraints []*coldef.TableConstraint) error {
+	m := map[string]bool{}
+
+	// check not empty constraint name do not have duplication.
+	for _, constr := range constraints {
+		if constr.ConstrName != "" {
+			nameLower := strings.ToLower(constr.ConstrName)
+			if m[nameLower] {
+				return errors.Errorf("CREATE TABLE: duplicate key %s", constr.ConstrName)
+			}
+			m[nameLower] = true
+		}
+	}
+
+	// set empty constraint names.
+	for _, constr := range constraints {
+		if constr.ConstrName == "" && len(constr.Keys) > 0 {
+			colName := constr.Keys[0].ColumnName
+			constrName := colName
+			i := 2
+			for m[strings.ToLower(constrName)] {
+				constrName = fmt.Sprintf("%s_%d", colName, i)
+				i++
+			}
+			constr.ConstrName = constrName
+			m[constrName] = true
+		}
+	}
+	return nil
+}
+
 func (d *ddl) buildTableInfo(tableName model.CIStr, cols []*column.Col, constraints []*coldef.TableConstraint) (tbInfo *model.TableInfo, err error) {
 	tbInfo = &model.TableInfo{
 		Name: tableName,
@@ -321,6 +353,11 @@ func (d *ddl) CreateTable(ctx context.Context, ident table.Ident, colDefs []*col
 		return errors.Trace(err)
 	}
 
+	err = checkConstraintNames(newConstraints)
+	if err != nil {
+		return errors.Trace(err)
+	}
+
 	tbInfo, err := d.buildTableInfo(ident.Name, cols, newConstraints)
 	if err != nil {
 		return errors.Trace(err)

ddl/ddl_test.go

@@ -134,6 +134,37 @@ func (ts *testSuite) TestT(c *C) {
 	c.Assert(err, IsNil)
 }
 
+func (ts *testSuite) TestConstraintNames(c *C) {
+	handle := infoschema.NewHandle(ts.store)
+	handle.Set(nil)
+	dd := ddl.NewDDL(ts.store, handle)
+	se, _ := tidb.CreateSession(ts.store)
+	ctx := se.(context.Context)
+	schemaName := model.NewCIStr("test")
+	tblName := model.NewCIStr("t")
+	tbIdent := table.Ident{
+		Schema: schemaName,
+		Name:   tblName,
+	}
+	err := dd.CreateSchema(ctx, tbIdent.Schema)
+	c.Assert(err, IsNil)
+	tbStmt := statement("create table t (a int, b int, index a (a, b), index a (a))").(*stmts.CreateTableStmt)
+	err = dd.CreateTable(ctx, tbIdent, tbStmt.Cols, tbStmt.Constraints)
+	c.Assert(err, NotNil)
+
+	tbStmt = statement("create table t (a int, b int, index A (a, b), index (a))").(*stmts.CreateTableStmt)
+	err = dd.CreateTable(ctx, tbIdent, tbStmt.Cols, tbStmt.Constraints)
+	c.Assert(err, IsNil)
+	tbl, err := handle.Get().TableByName(schemaName, tblName)
+	indices := tbl.Indices()
+	c.Assert(len(indices), Equals, 2)
+	c.Assert(indices[0].Name.O, Equals, "A")
+	c.Assert(indices[1].Name.O, Equals, "a_2")
+
+	err = dd.DropSchema(ctx, tbIdent.Schema)
+	c.Assert(err, IsNil)
+}
+
 func statement(sql string) stmt.Statement {
 	lexer := parser.NewLexer(sql)
 	parser.YYParse(lexer)