only check references for updated columns

enginetest/queries/foreign_key_queries.go

@@ -2581,6 +2581,41 @@ var ForeignKeyTests = []ScriptTest{
 			},
 		},
 	},
+	{
+		// https://github.com/dolthub/dolt/issues/7857
+		Name: "partial foreign key update",
+		SetUpScript: []string{
+			"create table parent1 (i int primary key);",
+			"create table child1 (" +
+				"i int primary key, " +
+				"j int, " +
+				"k int, " +
+				"index(j), " +
+				"index(k), " +
+				"foreign key (j) references parent1 (i)," +
+				"foreign key (k) references parent1 (i));",
+			"insert into parent1 values (1);",
+			"insert into child1 values (100, 1, 1);",
+			"set foreign_key_checks = 0;",
+			"insert into child1 values (101, 2, 2);",
+			"set foreign_key_checks = 1;",
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				Query: "update child1 set j = 1 where i = 101;",
+				Expected: []sql.Row{
+					{types.OkResult{RowsAffected: 1, Info: plan.UpdateInfo{Matched: 1, Updated: 1}}},
+				},
+			},
+			{
+				Query: "select * from child1",
+				Expected: []sql.Row{
+					{100, 1, 1},
+					{101, 1, 2},
+				},
+			},
+		},
+	},
 }
 
 var CreateForeignKeyTests = []ScriptTest{

sql/plan/foreign_key_editor.go

@@ -81,6 +81,21 @@ func (fkEditor *ForeignKeyEditor) IsInitialized(editors map[*ForeignKeyEditor]st
 // Update handles both the standard UPDATE statement and propagated referential actions from a parent table's ON UPDATE.
 func (fkEditor *ForeignKeyEditor) Update(ctx *sql.Context, old sql.Row, new sql.Row, depth int) error {
 	for _, reference := range fkEditor.References {
+		// Only check the reference for the columns that are updated
+		hasChange := false
+		for _, idx := range reference.RowMapper.IndexPositions {
+			cmp, err := fkEditor.Schema[idx].Type.Compare(old[idx], new[idx])
+			if err != nil {
+				return err
+			}
+			if cmp != 0 {
+				hasChange = true
+				break
+			}
+		}
+		if !hasChange {
+			continue
+		}
 		if err := reference.CheckReference(ctx, new); err != nil {
 			return err
 		}