Make auto-migrations tolerant to duplicate DDL

internal/repository/migrate/apply.go

@@ -2,14 +2,18 @@ package migrate
 
 import (
 	"database/sql"
+	"errors"
 	"fmt"
 	"strings"
 	"time"
+
+	"github.com/go-sql-driver/mysql"
 )
 
 // EnsureSchema applies all "up" migrations when the database has no tables.
 func EnsureSchema(db *sql.DB, dir string) error {
-	if err := ensureSchemaMigrations(db); err != nil {
+	columnName, err := ensureSchemaMigrations(db)
+	if err != nil {
 		return err
 	}
 
@@ -28,14 +32,14 @@ func EnsureSchema(db *sql.DB, dir string) error {
 			if err := execStatements(db, migration.SQL); err != nil {
 				return fmt.Errorf("apply %s: %w", migration.Name, err)
 			}
-			if err := recordMigration(db, migration.Name); err != nil {
+			if err := recordMigration(db, columnName, migration.Name); err != nil {
 				return err
 			}
 		}
 		return nil
 	}
 
-	applied, err := loadAppliedMigrations(db)
+	applied, err := loadAppliedMigrations(db, columnName)
 	if err != nil {
 		return err
 	}
@@ -46,7 +50,7 @@ func EnsureSchema(db *sql.DB, dir string) error {
 		if err := execStatements(db, migration.SQL); err != nil {
 			return fmt.Errorf("apply %s: %w", migration.Name, err)
 		}
-		if err := recordMigration(db, migration.Name); err != nil {
+		if err := recordMigration(db, columnName, migration.Name); err != nil {
 			return err
 		}
 	}
@@ -70,23 +74,71 @@ func execStatements(db *sql.DB, sqlText string) error {
 			continue
 		}
 		if _, err := db.Exec(stmt); err != nil {
+			var mysqlErr *mysql.MySQLError
+			if errors.As(err, &mysqlErr) && (mysqlErr.Number == 1060 || mysqlErr.Number == 1061) {
+				continue
+			}
 			return err
 		}
 	}
 	return nil
 }
 
-func ensureSchemaMigrations(db *sql.DB) error {
-	_, err := db.Exec(`CREATE TABLE IF NOT EXISTS schema_migrations (
+func ensureSchemaMigrations(db *sql.DB) (string, error) {
+	column, err := schemaMigrationsColumn(db)
+	if err != nil {
+		return "", err
+	}
+	if column != "" {
+		return column, nil
+	}
+
+	if _, err := db.Exec(`CREATE TABLE IF NOT EXISTS schema_migrations (
 		id BIGINT PRIMARY KEY AUTO_INCREMENT,
 		name VARCHAR(255) NOT NULL UNIQUE,
 		applied_at TIMESTAMP NOT NULL
-	)`)
-	return err
+	)`); err != nil {
+		return "", err
+	}
+
+	return "name", nil
 }
 
-func loadAppliedMigrations(db *sql.DB) (map[string]bool, error) {
-	rows, err := db.Query(`SELECT name FROM schema_migrations`)
+func schemaMigrationsColumn(db *sql.DB) (string, error) {
+	var nameCount int
+	if err := db.QueryRow(`
+		SELECT COUNT(*)
+		FROM information_schema.columns
+		WHERE table_schema = DATABASE()
+		  AND table_name = 'schema_migrations'
+		  AND column_name = 'name'
+	`).Scan(&nameCount); err != nil {
+		return "", err
+	}
+	if nameCount > 0 {
+		return "name", nil
+	}
+
+	var versionCount int
+	if err := db.QueryRow(`
+		SELECT COUNT(*)
+		FROM information_schema.columns
+		WHERE table_schema = DATABASE()
+		  AND table_name = 'schema_migrations'
+		  AND column_name = 'version'
+	`).Scan(&versionCount); err != nil {
+		return "", err
+	}
+	if versionCount > 0 {
+		return "version", nil
+	}
+
+	return "", nil
+}
+
+func loadAppliedMigrations(db *sql.DB, column string) (map[string]bool, error) {
+	query := fmt.Sprintf("SELECT %s FROM schema_migrations", column)
+	rows, err := db.Query(query)
 	if err != nil {
 		return nil, err
 	}
@@ -106,7 +158,8 @@ func loadAppliedMigrations(db *sql.DB) (map[string]bool, error) {
 	return applied, nil
 }
 
-func recordMigration(db *sql.DB, name string) error {
-	_, err := db.Exec(`INSERT INTO schema_migrations (name, applied_at) VALUES (?, ?)`, name, time.Now().UTC())
+func recordMigration(db *sql.DB, column, name string) error {
+	query := fmt.Sprintf("INSERT INTO schema_migrations (%s, applied_at) VALUES (?, ?)", column)
+	_, err := db.Exec(query, name, time.Now().UTC())
 	return err
 }