Direct query instead of source query

[PowerPlop]

If I understand correctly, Evidence will always extract data to a parquet file before querying it?

In my evidence page, I have multiple sales related queries.
For this mySQL source, I have to define a source query (e.g. select * from db.sales), so that I can use other queries in my page (e.g. select max(saleAmount) from sales).

So for each refresh, all full export is made from the source db, while I only need the summarized KPI which would have been performed more efficiently on the source db itself instead of locally on the parquet files?

Is there a way to choose whether the query is exectud on the db or on the parquet file?

[archiewood]

As context, pre universal-SQL support, this is how all Evidence queries worked (ran against data warehouse).

The problem this had, among others, is that you could only connect to a single database, and there was no support for client side interactivity.

We plan to add support for querying external data sources in the future, though this will likely be via DuckDB rather than using the data warehouse directly.
(For example, external parquet files)

In the meantime, you can do aggregation in the source layer if you need to, and just query the aggregates.

[PowerPlop]

Thanks for the clarification. I understand the benefit of introducing the universal SQL to allow combined queries.

How would the development flow be in this case:
Assume I have a datasource with +- 15 tables I want to combine in a report, should I..

• add a separate source query for each table and join in page queries
• create one big table source query (that will be selected and filtered in later page queries)
  • write one big table query in data warehouse and simply select in source query
• create aggregated views in the data warehouse (e.g. max sales, sales per country, sales per order) and 1-1 select in source and page query

Worst case I have 3 differenent places where I need to modify my sql when building the report. Page queries will be refreshed instantly, but when having to edit source or data warehouse queries I need to rerun all data before I can continue.

Is there a way to bypass source queries and work directly with page queries? (maybe only as a development option)

Not criticizing the way Evidence works, just trying the understand what the best way is!