A suggestion that may integrate a lot of ideas which have been previously suggested…
Ragic is a fairly sophisticated relational database with a GUI spreadsheet front end. Think of it like Airtable with much more capable features in terms of table relationships, formatting, and reporting plus the ability to write custom Javascript. It also can be configured to automatically import/update data daily from Google Sheets or other sources. And it has an API.
I think an integration between Ragic and Coda would be stunning and would simultaneously address many of the issues we have discussed here. It scales to a million or more records and it can handle many of the database-oriented use cases not quite within Coda’s capability and it can sync with an external data source automatically. Of course Coda excels in the presentation; Coda is the ultimate front-end whereas Ragic would be a great back end to feed data to Coda.
To integrate these one would essentially use the Ragic API and/or new Coda API to match specific tables between the two and then update or Sync Coda on a regular basis with the corresponding tables in Ragic.