Table system.schema_keyspaces renamed to system_schema.keyspaces in cassandra versions >= 4

[vikingUnet]

Hello!

Get errors in cassandra audit log file:

SELECT durable_writes, strategy_class, strategy_options
FROM system.schema_keyspaces
WHERE keyspace_name = ?; table schema_keyspaces does not exist

But this table was renamed to system_schema.keyspaces long time ago in version 4.
Please, fix it.
Thanks!

[worryg0d]

Hi @vikingUnet

This is completely normal behaviour for gocql, as this is actually part of the mechanism that allows the driver to determine which system keyspace to use: system or system_schema. You can find its code here:

func checkSystemSchema(control *controlConn) (bool, error) {
	iter := control.query("SELECT * FROM system_schema.keyspaces")
	if err := iter.err; err != nil {
		if errf, ok := err.(*errorFrame); ok {
			if errf.code == ErrCodeSyntax {
				return false, nil
			}
		}

		return false, err
	}

	return true, nil
}

So this basically just tries to query system_schema.keyspaces, and if there is no such keyspace, it will just return true, which means that gocql should use the older one

This mechanism is only triggered during session initialisation, so it doesn't have a big impact on performance

[joao-r-reis]

If this is causing issues we could switch to the way other drivers do it which is by checking the C* version returned by system.local

[joao-r-reis]

Oh actually it already does check the C* version, it only doesn't do that when !s.cfg.disableControlConn && s.cfg.DisableInitialHostLookup for obvious reasons. But in any case it would start with the newer "form" so this wouldn't result in the issue that is being described... There's something else we're not understanding here

[joao-r-reis]

Also I think system.schema_keyspaces was renamed to system_schema.keyspaces in C* 3.0 not 4

[worryg0d]

Oh, I'm dumb. The log says system.schema_keyspaces, not system_schema.keyspaces:

Quick searching for the SELECT durable_writes, strategy_class, strategy_options query in gocql codebase:

1. getKeyspaceMetadata() method which
2. The above method is being called by schemaDescriber.refreshSchema
3. refreshScema called by schemaDescriber.getSchema()
4. And finnaly this is being called by public Session.KeyspaceMetadata() method

So session.useSystemSchema is false for some reason....

[worryg0d]

If this is possible, could you please share:

1. exact gocql version
2. gocql ClusterConfig, if it is possible
3. If your target cluster consists of nodes with different C* versions (e.g., 4.0 and 3.11)