fix(db): keep same-column indexes in different order on sync

xorm pairs declared and existing indexes by column set, ignoring name
and column order, so on every sync the `action` table could drop one of
`c_u` and `c_u_d`, and never recreate a missing one. Tables with such
index pairs are now synced with IgnoreIndices and their plain indexes are
reconciled by name.

Fix https://github.com/go-gitea/gitea/issues/39244

models/db/engine_test.go

@@ -7,6 +7,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	activities_model "gitea.dev/models/activities"
 	"gitea.dev/models/db"
 	issues_model "gitea.dev/models/issues"
 	"gitea.dev/models/unittest"
@@ -16,6 +17,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"xorm.io/xorm/schemas"
 )
 
 func TestDumpDatabase(t *testing.T) {
@@ -34,6 +36,46 @@ func TestDumpDatabase(t *testing.T) {
 	}
 }
 
+func TestSyncAllTablesKeepsSameColumnIndexes(t *testing.T) {
+	// action declares c_u and c_u_d with the same columns in different order
+	require.NoError(t, unittest.PrepareTestDatabase())
+	x := db.GetXORMEngineForTesting()
+
+	table, err := x.TableInfo(new(activities_model.Action))
+	require.NoError(t, err)
+	declared := map[string][]string{}
+	for name, index := range table.Indexes {
+		declared[name] = index.Cols
+	}
+	require.Contains(t, declared, "c_u")
+	require.Contains(t, declared, "c_u_d")
+
+	existing := func() (map[string][]string, map[string]*schemas.Index) {
+		indexes, err := x.Dialect().GetIndexes(x.DB(), t.Context(), table.Name)
+		require.NoError(t, err)
+		cols := map[string][]string{}
+		for name, index := range indexes {
+			cols[name] = index.Cols
+		}
+		return cols, indexes
+	}
+
+	for range 10 {
+		require.NoError(t, db.SyncAllTables())
+		cols, _ := existing()
+		require.Equal(t, declared, cols)
+	}
+
+	for _, name := range []string{"c_u", "c_u_d"} {
+		_, indexes := existing()
+		_, err = x.Exec(x.Dialect().DropIndexSQL(table.Name, indexes[name]))
+		require.NoError(t, err)
+		require.NoError(t, db.SyncAllTables())
+		cols, _ := existing()
+		assert.Equal(t, declared, cols, "index %s should be restored", name)
+	}
+}
+
 func TestDeleteOrphanedObjects(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())