breaking change: add a column to the version table to record whether we migrated up or down. fixes the case in which we weren't correctly calculating the current version previously in some cases, and also allows us to maintain a more complete historic record of all migrations made.

migrate.go

@@ -18,6 +18,7 @@ import (
 type DBVersion struct {
 	VersionId int
 	TStamp    time.Time
+	IsApplied bool // was this a result of up() or down()
 }
 
 type Migration struct {
@@ -200,35 +201,72 @@ func numericComponent(name string) (int, error) {
 // Create and initialize the DB version table if it doesn't exist.
 func ensureDBVersion(db *sql.DB) (int, error) {
 
-	dbversion := int(0)
-	row := db.QueryRow("SELECT version_id from goose_db_version ORDER BY tstamp DESC LIMIT 1;")
-
-	if err := row.Scan(&dbversion); err == nil {
-		return dbversion, nil
+	rows, err := db.Query("SELECT version_id, is_applied from goose_db_version ORDER BY tstamp DESC;")
+	if err != nil {
+		// XXX: cross platform method to detect failure reason
+		// for now, assume it was because the table didn't exist, and try to create it
+		return 0, createVersionTable(db)
 	}
 
-	// if we failed, assume that the table didn't exist, and try to create it
+	// The most recent record for each migration specifies
+	// whether it has been applied or rolled back.
+	// The first version we find that has been applied is the current version.
+
+	toSkip := make([]int, 0)
+
+	for rows.Next() {
+		var row DBVersion
+		if err = rows.Scan(&row.VersionId, &row.IsApplied); err != nil {
+			log.Fatal("error scanning rows:", err)
+		}
+
+		// have we already marked this version to be skipped?
+		skip := false
+		for _, v := range toSkip {
+			if v == row.VersionId {
+				skip = true
+				break
+			}
+		}
+
+		// if version has been applied and not marked to be skipped, we're done
+		if row.IsApplied && !skip {
+			return row.VersionId, nil
+		}
+
+		// version is either not applied, or we've already seen a more
+		// recent version of it that was not applied.
+		if !skip {
+			toSkip = append(toSkip, row.VersionId)
+		}
+	}
+
+	panic("failure in ensureDBVersion()")
+}
+
+func createVersionTable(db *sql.DB) error {
 	txn, err := db.Begin()
 	if err != nil {
-		return 0, err
+		return err
 	}
 
 	// create the table and insert an initial value of 0
 	create := `CREATE TABLE goose_db_version (
                 version_id int NOT NULL,
+                is_applied boolean NOT NULL,
                 tstamp timestamp NULL default now(),
                 PRIMARY KEY(tstamp)
               );`
-	insert := "INSERT INTO goose_db_version (version_id) VALUES (0);"
+	insert := "INSERT INTO goose_db_version (version_id, is_applied) VALUES (0, true);"
 
 	for _, str := range []string{create, insert} {
 		if _, err := txn.Exec(str); err != nil {
 			txn.Rollback()
-			return 0, err
+			return err
 		}
 	}
 
-	return 0, txn.Commit()
+	return txn.Commit()
 }
 
 // wrapper for ensureDBVersion for callers that don't already have

migration_go.go

@@ -196,13 +196,9 @@ func main() {
 
 	migration_{{ .Version }}_{{ .Direction }}(txn)
 
-	v := {{ .Version }}
-	if "{{ .Direction }}" == "Down" {
-		v--
-	}
-
 	// XXX: drop goose_db_version table on some minimum version number?
-	versionStmt := fmt.Sprintf("INSERT INTO goose_db_version (version_id) VALUES (%d);", v)
+    isApplied := "{{ .Direction }}" == "Up"
+	versionStmt := fmt.Sprintf("INSERT INTO goose_db_version (version_id, is_applied) VALUES (%d, %t);", {{ .Version }}, isApplied)
 	if _, err = txn.Exec(versionStmt); err != nil {
 		txn.Rollback()
 		log.Fatal("failed to write version: ", err)

migration_sql.go

@@ -72,12 +72,8 @@ func runSQLMigration(db *sql.DB, script string, v int, direction bool) (count in
 // and finalize the transaction.
 func finalizeMigration(txn *sql.Tx, direction bool, v int) error {
 
-	if direction == false {
-		v--
-	}
-
 	// XXX: drop goose_db_version table on some minimum version number?
-	versionStmt := fmt.Sprintf("INSERT INTO goose_db_version (version_id) VALUES (%d);", v)
+	versionStmt := fmt.Sprintf("INSERT INTO goose_db_version (version_id, is_applied) VALUES (%d, %t);", v, direction)
 	if _, err := txn.Exec(versionStmt); err != nil {
 		txn.Rollback()
 		return err