ddl: check foreign key constraint when drop,modify,change column (#14043)

ddl/column.go

@@ -452,6 +452,16 @@ func isColumnWithIndex(colName string, indices []*model.IndexInfo) bool {
 	}
 	return false
 }
+func getColumnForeignKeyInfo(colName string, fkInfos []*model.FKInfo) *model.FKInfo {
+	for _, fkInfo := range fkInfos {
+		for _, col := range fkInfo.Cols {
+			if col.L == colName {
+				return fkInfo
+			}
+		}
+	}
+	return nil
+}
 
 func allocateColumnID(tblInfo *model.TableInfo) int64 {
 	tblInfo.MaxColumnID++

ddl/db_test.go

@@ -2173,7 +2173,20 @@ func (s *testDBSuite) TestTableForeignKey(c *C) {
 	s.tk.MustExec("create table t3 (a int, b int);")
 	failSQL = "alter table t1 add foreign key (c) REFERENCES t3(a);"
 	s.testErrorCode(c, failSQL, tmysql.ErrKeyColumnDoesNotExits)
-	s.tk.MustExec("drop table if exists t1,t2,t3;")
+	// Test drop column with foreign key.
+	s.tk.MustExec("create table t4 (c int,d int,foreign key (d) references t1 (b));")
+	failSQL = "alter table t4 drop column d"
+	s.testErrorCode(c, failSQL, mysql.ErrFkColumnCannotDrop)
+	// Test change column with foreign key.
+	failSQL = "alter table t4 change column d e bigint;"
+	s.testErrorCode(c, failSQL, mysql.ErrFKIncompatibleColumns)
+	// Test modify column with foreign key.
+	failSQL = "alter table t4 modify column d bigint;"
+	s.testErrorCode(c, failSQL, mysql.ErrFKIncompatibleColumns)
+	s.tk.MustQuery("select count(*) from information_schema.KEY_COLUMN_USAGE;")
+	s.tk.MustExec("alter table t4 drop foreign key d")
+	s.tk.MustExec("alter table t4 modify column d bigint;")
+	s.tk.MustExec("drop table if exists t1,t2,t3,t4;")
 }
 
 func (s *testDBSuite) TestBitDefaultValue(c *C) {

ddl/ddl.go

@@ -115,6 +115,8 @@ var (
 	errTooManyFields            = terror.ClassDDL.New(codeTooManyFields, "Too many columns")
 	errInvalidSplitRegionRanges = terror.ClassDDL.New(codeInvalidRanges, "Failed to split region ranges")
 	errReorgPanic               = terror.ClassDDL.New(codeReorgWorkerPanic, "reorg worker panic.")
+	errFkColumnCannotDrop       = terror.ClassDDL.New(codeFkColumnCannotDrop, mysql.MySQLErrName[mysql.ErrFkColumnCannotDrop])
+	errReferencedForeignKey     = terror.ClassDDL.New(codeFKIncompatibleColumns, mysql.MySQLErrName[mysql.ErrFKIncompatibleColumns])
 
 	// errWrongKeyColumn is for table column cannot be indexed.
 	errWrongKeyColumn = terror.ClassDDL.New(codeWrongKeyColumn, mysql.MySQLErrName[mysql.ErrWrongKeyColumn])
@@ -662,6 +664,8 @@ const (
 	codePrimaryCantHaveNull                    = terror.ErrCode(mysql.ErrPrimaryCantHaveNull)
 	codeWrongExprInPartitionFunc               = terror.ErrCode(mysql.ErrWrongExprInPartitionFunc)
 	codeUnknownPartition                       = terror.ErrCode(mysql.ErrUnknownPartition)
+	codeFkColumnCannotDrop                     = terror.ErrCode(mysql.ErrFkColumnCannotDrop)
+	codeFKIncompatibleColumns                  = terror.ErrCode(mysql.ErrFKIncompatibleColumns)
 )
 
 func init() {
@@ -715,6 +719,8 @@ func init() {
 		codeUnknownCollation:                       mysql.ErrUnknownCollation,
 		codeCollationCharsetMismatch:               mysql.ErrCollationCharsetMismatch,
 		codeConflictingDeclarations:                mysql.ErrConflictingDeclarations,
+		codeFkColumnCannotDrop:                     mysql.ErrFkColumnCannotDrop,
+		codeFKIncompatibleColumns:                  mysql.ErrFKIncompatibleColumns,
 	}
 	terror.ErrClassToMySQLCodes[terror.ClassDDL] = ddlMySQLErrCodes
 }

ddl/ddl_api.go

@@ -2080,6 +2080,11 @@ func (d *ddl) getModifiableColumnJob(ctx sessionctx.Context, ident ast.Ident, or
 		}
 	}
 
+	// Check the column with foreign key.
+	if fkInfo := getColumnForeignKeyInfo(originalColName.L, t.Meta().ForeignKeys); fkInfo != nil {
+		return nil, errReferencedForeignKey.GenWithStackByArgs(originalColName, fkInfo.Name)
+	}
+
 	// Constraints in the new column means adding new constraints. Errors should thrown,
 	// which will be done by `setDefaultAndComment` later.
 	if specNewColumn.Tp == nil {
@@ -2729,6 +2734,10 @@ func isDroppableColumn(tblInfo *model.TableInfo, colName model.CIStr) error {
 	if isColumnWithIndex(colName.L, tblInfo.Indices) {
 		return errCantDropColWithIndex.GenWithStack("can't drop column %s with index covered now", colName)
 	}
+	// Check the column with foreign key.
+	if fkInfo := getColumnForeignKeyInfo(colName.L, tblInfo.ForeignKeys); fkInfo != nil {
+		return errFkColumnCannotDrop.GenWithStackByArgs(colName, fkInfo.Name)
+	}
 	return nil
 }
 

go.mod

@@ -52,7 +52,7 @@ require (
 	github.com/pingcap/goleveldb v0.0.0-20171020084629-8d44bfdf1030
 	github.com/pingcap/kvproto v0.0.0-20190826051950-fc8799546726
 	github.com/pingcap/log v0.0.0-20190307075452-bd41d9273596
-	github.com/pingcap/parser v0.0.0-20191118062231-d32e257db9f2
+	github.com/pingcap/parser v0.0.0-20191220111854-63cc130be9fa
 	github.com/pingcap/pd v2.1.12+incompatible
 	github.com/pingcap/tidb-tools v2.1.3-0.20190116051332-34c808eef588+incompatible
 	github.com/pingcap/tipb v0.0.0-20191120045257-1b9900292ab6

go.sum

@@ -109,8 +109,8 @@ github.com/pingcap/kvproto v0.0.0-20190826051950-fc8799546726 h1:AzGIEmaYVYMtmki
 github.com/pingcap/kvproto v0.0.0-20190826051950-fc8799546726/go.mod h1:0gwbe1F2iBIjuQ9AH0DbQhL+Dpr5GofU8fgYyXk+ykk=
 github.com/pingcap/log v0.0.0-20190307075452-bd41d9273596 h1:t2OQTpPJnrPDGlvA+3FwJptMTt6MEPdzK1Wt99oaefQ=
 github.com/pingcap/log v0.0.0-20190307075452-bd41d9273596/go.mod h1:WpHUKhNZ18v116SvGrmjkA9CBhYmuUTKL+p8JC9ANEw=
-github.com/pingcap/parser v0.0.0-20191118062231-d32e257db9f2 h1:aPvPSsdQe2pLd4fTky0zQKjLXqj6jYvE6R4DEavod3Y=
-github.com/pingcap/parser v0.0.0-20191118062231-d32e257db9f2/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
+github.com/pingcap/parser v0.0.0-20191220111854-63cc130be9fa h1:cDcoEb9rNlWifDVHGcBTFecK3MU4/Q2+LdJa6X6iK8Q=
+github.com/pingcap/parser v0.0.0-20191220111854-63cc130be9fa/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
 github.com/pingcap/pd v2.1.12+incompatible h1:6N3LBxx2aSZqT+IWEG730EDNDttP7dXO8J6yvBh+HXw=
 github.com/pingcap/pd v2.1.12+incompatible/go.mod h1:nD3+EoYes4+aNNODO99ES59V83MZSI+dFbhyr667a0E=
 github.com/pingcap/tidb-tools v2.1.3-0.20190116051332-34c808eef588+incompatible h1:e9Gi/LP9181HT3gBfSOeSBA+5JfemuE4aEAhqNgoE4k=