ALTER INDEX syntax is not supported

[dtest]

Expected Behavior

Creating a migration file to ALTER INDEX should succeed as per Spanner DDL docs

Current Behavior

Fails with errors like:

Error command: up, version: unknown
        failed to parse DDL/DML statements: <file>.sql:1.0: unknown DDL statement, <file>.sql:1.0: unknown DML statement

Steps to Reproduce

1. Start with schema file like ./schema/schema.sql:

CREATE TABLE players (
  playerUUID STRING(36) NOT NULL,
  player_name STRING(64) NOT NULL,
  email STRING(MAX) NOT NULL,
  password_hash BYTES(60) NOT NULL,  
  is_logged_in BOOL,
) PRIMARY KEY(playerUUID);

CREATE UNIQUE INDEX PlayerAuthentication ON players(email) STORING (password_hash);

2. Create the database using wrench:

wrench create --directory ./schema

3. Create a new migration file

wrench migrate create --directory ./schema

# cat ./schema/migrations/000001.sql
ALTER INDEX PlayerAuthentication ADD STORED COLUMN is_logged_in;

4. Run migration:

wrench migrate up --directory ./schema

Context (Environment)

• wrench version: 1.3.3

The workaround is to drop index and recreate. But it'd be nice to have ALTER INDEX supported.