ddl: Add a limit for columns in a table (pingcap#4464)

Yui-Song · Sep 7, 2017 · 20a928e · 20a928e
1 parent f380a74
commit 20a928e
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Showing 3 changed files with 25 additions and 1 deletion.
diff --git a/ddl/ddl.go b/ddl/ddl.go
@@ -49,6 +49,12 @@ const (
 	ddlPrompt   = "ddl"
 )
 
+var (
+	// TableColumnCountLimit is limit of the number of columns in a table.
+	// It's exported for testing.
+	TableColumnCountLimit = 512
+)
+
 var (
 	// errWorkerClosed means we have already closed the DDL worker.
 	errInvalidWorker = terror.ClassDDL.New(codeInvalidWorker, "invalid worker")
@@ -81,6 +87,7 @@ var (
 	errErrorOnRename         = terror.ClassDDL.New(codeErrorOnRename, "Error on rename of './%s/%s' to './%s/%s'")
 	errBadField              = terror.ClassDDL.New(codeBadField, "Unknown column '%s' in '%s'")
 	errInvalidUseOfNull      = terror.ClassDDL.New(codeInvalidUseOfNull, "Invalid use of NULL value")
+	errTooManyFields         = terror.ClassDDL.New(codeTooManyFields, "Too many columns")
 
 	// errWrongKeyColumn is for table column cannot be indexed.
 	errWrongKeyColumn = terror.ClassDDL.New(codeWrongKeyColumn, mysql.MySQLErrName[mysql.ErrWrongKeyColumn])
@@ -541,6 +548,7 @@ const (
 	codeBlobCantHaveDefault          = 1101
 	codeWrongDBName                  = 1102
 	codeWrongTableName               = 1103
+	codeTooManyFields                = 1117
 	codeInvalidUseOfNull             = 1138
 	codeWrongColumnName              = 1166
 	codeWrongKeyColumn               = 1167
@@ -579,6 +587,7 @@ func init() {
 		codeWrongColumnName:              mysql.ErrWrongColumnName,
 		codeWrongKeyColumn:               mysql.ErrWrongKeyColumn,
 		codeWrongNameForIndex:            mysql.ErrWrongNameForIndex,
+		codeTooManyFields:                mysql.ErrTooManyFields,
 	}
 	terror.ErrClassToMySQLCodes[terror.ClassDDL] = ddlMySQLErrCodes
 }
diff --git a/ddl/ddl_api.go b/ddl/ddl_api.go
@@ -478,6 +478,13 @@ func checkTooLongColumn(colDefs []*ast.ColumnDef) error {
 	return nil
 }
 
+func checkTooManyColumns(colDefs []*ast.ColumnDef) error {
+	if len(colDefs) > TableColumnCountLimit {
+		return errTooManyFields
+	}
+	return nil
+}
+
 func checkDuplicateConstraint(namesMap map[string]bool, name string, foreign bool) error {
 	if name == "" {
 		return nil
@@ -708,6 +715,9 @@ func (d *ddl) CreateTable(ctx context.Context, ident ast.Ident, colDefs []*ast.C
 	if err = checkTooLongColumn(colDefs); err != nil {
 		return errors.Trace(err)
 	}
+	if err = checkTooManyColumns(colDefs); err != nil {
+		return errors.Trace(err)
+	}
 
 	cols, newConstraints, err := buildColumnsAndConstraints(ctx, colDefs, constraints)
 	if err != nil {

diff --git a/ddl/ddl_db_test.go b/ddl/ddl_db_test.go
@@ -1094,8 +1094,13 @@ func (s *testDBSuite) TestCreateTableTooLarge(c *C) {
 		}
 	}
 	sql += ");"
+	s.testErrorCode(c, sql, tmysql.ErrTooManyFields)
+
+	originLimit := ddl.TableColumnCountLimit
+	ddl.TableColumnCountLimit = cnt * 4
 	_, err := s.tk.Exec(sql)
-	c.Assert(kv.ErrEntryTooLarge.Equal(err), IsTrue, Commentf("sql:%v", sql))
+	c.Assert(kv.ErrEntryTooLarge.Equal(err), IsTrue, Commentf("err:%v", err))
+	ddl.TableColumnCountLimit = originLimit
 }
 
 func (s *testDBSuite) TestCreateTableWithLike(c *C) {