Migration on Clickhouse fails if the file only contains a comment

[sboomsma]

According to the documentation empty migrations is permitted by migrate (see here)

The migration files are permitted to be "empty", in the event that a migration is a no-op or is irreversible. It is recommended to still include both migration files by making the whole migration file consist of a comment. If your database does not support comments, then deleting the migration file will also work. Note, an actual empty file (e.g. a 0 byte file) may cause issues with your database since migrate will attempt to run an empty query. In this case, deleting the migration file will also work. For the rational of this behavior see: #244 (comment)

It seems for clickhouse that having a file with just a comment still causes an empty query error:

error: migration failed in line 0:  (details: code: 62, message: Empty query)

Steps to Reproduce
Steps to reproduce the behavior:

1. Create a new clickhouse DB migration, leaving the up migration file empty.

$ migrate -ext migrations -dir migrations empty_up_test
$ echo "-- Empty file, because we need multiple down migrations to under the next up migration" > migrations/2020904120200_empty_up_test.migration

2. Perform the up migration:

$ migrate -path migrations -source "${MIGRATE_DB}" up

3. See error

Expected Behavior
I would expect that a up migration file with an empty script would simply update the schema_migrations table to the new version

Migrate Version
4.12.2

Loaded Source Drivers
github, github-ee, gitlab, go-bindata, godoc-vfs, gcs, file, s3

Loaded Database Drivers
cockroachdb, firebird, mysql, sqlserver, cassandra, firebirdsql, redshift, spanner, neo4j, postgres, postgresql, clickhouse, cockroach, crdb-postgres, mongodb, mongodb+srv, stub

Go Version
go version go1.14.4 linux/amd64

[dhui]

It looks like Clickhouse doesn't support empty queries or queries with only comments. There's nothing actionable for migrate since migrate avoids processing or interpreting migration data/content. e.g. migration content/data is treated as opaque binary blobs
See: #244 (comment)

I find it odd that you're getting the same 1065 MySQL/MariaDB error in Clickhouse

[sboomsma]

Ah yes, I've fixed the original report to the correct 62 code.

Ok, I think the phrasing in the documentation could be improved in this regard but happy to close.