Skip fk validation on CREATE TABLE when fks are disabled

enginetest/enginetests.go

@@ -1947,6 +1947,24 @@ func TestCreateForeignKeys(t *testing.T, harness Harness) {
 		RunQuery(t, e, harness, "CREATE TABLE child3 (pk BIGINT PRIMARY KEY);")
 		TestQuery(t, harness, e, "ALTER TABLE child3 ADD COLUMN v1 BIGINT NULL, ADD CONSTRAINT fk_child3 FOREIGN KEY (v1) REFERENCES parent3(v1);", []sql.Row(nil), nil, nil)
 	})
+
+	TestScript(t, harness, ScriptTest{
+		Name: "Do not validate foreign keys if FOREIGN_KEY_CHECKS is set to zero",
+		Assertions: []ScriptTestAssertion{
+			{
+				Query:    "SET FOREIGN_KEY_CHECKS=0;",
+				Expected: []sql.Row{{}},
+			},
+			{
+				Query:    "CREATE TABLE child4 (pk BIGINT PRIMARY KEY, CONSTRAINT fk_child4 FOREIGN KEY (pk) REFERENCES delayed_parent4 (pk))",
+				Expected: nil,
+			},
+			{
+				Query:    "CREATE TABLE delayed_parent4 (pk BIGINT PRIMARY KEY)",
+				Expected: nil,
+			},
+		},
+	})
 }
 
 func TestDropForeignKeys(t *testing.T, harness Harness) {

go.sum

@@ -126,7 +126,6 @@ golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20190425150028-36563e24a262/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
 golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
-golang.org/x/tools v0.0.0-20190830154057-c17b040389b9 h1:5/jaG/gKlo3xxvUn85ReNyTlN7BvlPPsxC6sHZKjGEE=
 golang.org/x/tools v0.0.0-20190830154057-c17b040389b9/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=

sql/errors.go

@@ -264,6 +264,9 @@ var (
 	// ErrForeignKeyColumnCountMismatch is called when the declared column and referenced column counts do not match.
 	ErrForeignKeyColumnCountMismatch = errors.NewKind("the foreign key must reference an equivalent number of columns")
 
+	// ErrForeignKeyNotResolved is called when an add or update is attempted on a foreign key that has not been resolved yet.
+	ErrForeignKeyNotResolved = errors.NewKind("cannot add or update a child row: a foreign key constraint fails (`%s`, CONSTRAINT `%s` FOREIGN KEY (`%s`) REFERENCES `%s` (`%s`))")
+
 	// ErrDuplicateEntry is returns when a duplicate entry is placed on an index such as a UNIQUE or a Primary Key.
 	ErrDuplicateEntry = errors.NewKind("Duplicate entry for key '%s'")
 

sql/plan/ddl.go

@@ -296,17 +296,38 @@ func (c *CreateTable) createForeignKeys(ctx *sql.Context, tableNode sql.Table) e
 		return ErrNoForeignKeySupport.New(c.name)
 	}
 
-	for _, fkDef := range c.fkDefs {
-		refTbl, ok, err := c.db.GetTableInsensitive(ctx, fkDef.ReferencedTable)
-		if err != nil {
-			return err
-		}
-		if !ok {
-			return sql.ErrTableNotFound.New(fkDef.ReferencedTable)
+	fkChecks, err := ctx.GetSessionVariable(ctx, "foreign_key_checks")
+	if err != nil {
+		return err
+	}
+	if fkChecks.(int8) == 1 {
+		for _, fkDef := range c.fkDefs {
+			refTbl, ok, err := c.db.GetTableInsensitive(ctx, fkDef.ReferencedTable)
+			if err != nil {
+				return err
+			}
+			if !ok {
+				return sql.ErrTableNotFound.New(fkDef.ReferencedTable)
+			}
+			err = executeCreateForeignKey(ctx, fkAlterable, refTbl, fkDef)
+			if err != nil {
+				return err
+			}
 		}
-		err = executeCreateForeignKey(ctx, fkAlterable, refTbl, fkDef)
-		if err != nil {
-			return err
+	} else {
+		for _, fkDef := range c.fkDefs {
+			err = fkAlterable.CreateForeignKey(
+				ctx,
+				fkDef.Name,
+				fkDef.Columns,
+				fkDef.ReferencedTable,
+				fkDef.ReferencedColumns,
+				fkDef.OnUpdate,
+				fkDef.OnDelete,
+			)
+			if err != nil {
+				return err
+			}
 		}
 	}