[keithb-]

I thought that's what solutions like Calcite[1] were for: running queries across disparate data sources. Yes, you still need to have adapters for each source to normalize access semantics. No, not all sources will have the same schema. But if you're trying to combine Postgres and DynamoDB into a single query, you would narrow your view to something that exists in both places, e.g. customer keys, meta data, etc.

Maybe I'm wrong.

[1] https://calcite.apache.org/

[manigandham]

Calcite is only a SQL parser and planner. It doesn't execute anything and is meant to be a component in a larger database system.

You need to use something like Spark, Presto or Drill if you want to run queries across different data sources.