corrected code for table name filtering

Use $connection->getConfiguration()->setFilterSchemaAssetsExpression() to set a part of table names as a regular expression. listTableNames, listTables (using listTableNames) and listSequences will deliver only those tables/sequences its names match that regular expression.
This looks wrong. Why would you expect `$assetName` to be an array? Also what's the purpose of looking up the key `relaname`? Where does it come from?