We are able to pull multiple schemas for new Redshift and BigQuery sources. For other data sources you currently can only have one schema per data source connection in Chartio, so you would need to add any additional schemas as separate data sources.
However, there is a workaround: you can create custom tables that pull from tables in your other schema(s). Custom tables allow you to write SQL that Chartio inserts directly into Interactive Mode queries. So, you could create a custom table with the following SQL (replacing schema_name and table_name with relevant information from your database):
SELECT * FROM schema_name.table_name
For reference, you can run the following command to view all available tables and views in all schemas (MySQL/PostgreSQL):
SELECT * FROM information_schema.tables