Distinguish inferred migrations by timestamp for statements within the same transaction (#362)

Set `created_at` and `updated_at` explicitly when inserting inferred
migrations into the migrations table.

When two statements are run in a transaction, we need to explicitly
insert `statement_timestamp()` into the `created_at` and `updated_at`
fields rather than relying on the table default of `current_timestamp`.

`current_timestamp` is the same for all statements in a transaction,
which causes problems when ordering statements by `created_at`.


Fixes #361

pkg/state/state.go

@@ -309,7 +309,7 @@ BEGIN
 	-- Someone did a schema change without pgroll, include it in the history
 	SELECT INTO migration_id pg_catalog.format('sql_%%s',pg_catalog.substr(pg_catalog.md5(pg_catalog.random()::text), 0, 15));
 
-	INSERT INTO %[1]s.migrations (schema, name, migration, resulting_schema, done, parent, migration_type)
+	INSERT INTO %[1]s.migrations (schema, name, migration, resulting_schema, done, parent, migration_type, created_at, updated_at)
 	VALUES (
 		schemaname,
 		migration_id,
@@ -328,7 +328,9 @@ BEGIN
 		%[1]s.read_schema(schemaname),
 		true,
 		%[1]s.latest_version(schemaname),
-		'inferred'
+		'inferred',
+		statement_timestamp(),
+		statement_timestamp()
 	);
 END;
 $$;

pkg/state/state_test.go

@@ -10,10 +10,12 @@ import (
 	"strings"
 	"sync"
 	"testing"
+	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	"github.com/xataio/pgroll/pkg/migrations"
 	"github.com/xataio/pgroll/pkg/schema"
 	"github.com/xataio/pgroll/pkg/state"
@@ -272,6 +274,55 @@ func TestInferredMigration(t *testing.T) {
 	})
 }
 
+func TestInferredMigrationsInTransactionHaveDifferentTimestamps(t *testing.T) {
+	ctx := context.Background()
+
+	testutils.WithStateAndConnectionToContainer(t, func(state *state.State, db *sql.DB) {
+		// Start a transaction
+		tx, err := db.BeginTx(ctx, nil)
+		require.NoError(t, err)
+		defer tx.Rollback()
+
+		// Create two tables in the transaction
+		_, err = tx.ExecContext(ctx, "CREATE TABLE table1 (id int)")
+		require.NoError(t, err)
+
+		_, err = tx.ExecContext(ctx, "CREATE TABLE table2 (id int)")
+		require.NoError(t, err)
+
+		// Commit the transaction
+		tx.Commit()
+
+		// Read the migrations from the migrations table
+		rows, err := db.QueryContext(ctx,
+			fmt.Sprintf("SELECT name, created_at, updated_at FROM %s.migrations ORDER BY created_at ASC", state.Schema()))
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer rows.Close()
+
+		type m struct {
+			name      string
+			createdAt time.Time
+			updatedAt time.Time
+		}
+		var migrations []m
+
+		for rows.Next() {
+			var migration m
+			if err := rows.Scan(&migration.name, &migration.createdAt, &migration.updatedAt); err != nil {
+				t.Fatal(err)
+			}
+
+			migrations = append(migrations, migration)
+		}
+
+		// Ensure that the two inferred migrations have different timestamps
+		assert.Equal(t, 2, len(migrations), "unexpected number of migrations")
+		assert.NotEqual(t, migrations[0].createdAt, migrations[1].createdAt, "migrations have the same timestamp")
+	})
+}
+
 func TestPgRollInitializationInANonDefaultSchema(t *testing.T) {
 	t.Parallel()