Parquet queries stop returning results after refresh on Windows

The problem

When I write queries against parquet files tagged in the 'sql' preamble, they'll work as I'm starting to develop a report, but as I continue to iterate, they'll stop returning results entirely. It only seems to happen with medium+ sized files.

The fix

If your Parquet-backed SQL queries in Observable Framework work at first but return no results after a refresh on Windows, it is the framework's aggressive file-attachment cache, not your query. This is a Windows-specific caching problem with medium+ sized Parquet files. Workarounds for avoiding the cache are documented in the linked discussion (observablehq/framework discussions/1691, mbostock's comment). Treat 'No results' after refresh as a cache problem first.

In gh:observablehq/framework#1470 (https://github.com/observablehq/framework/issues/1470), the reporter ran into this: When I write queries against parquet files tagged in the 'sql' preamble, they'll work as I'm starting to develop a report, but as I continue to iterate, they'll stop returning results entirely. It only seems to happen with medium+ sized files. The verified resolution: If your Parquet-backed SQL queries in Observable Framework work at first but return no results after a refresh on Windows, it is the framework's aggressive file-attachment cache, not your query. This is a Windows-specific caching problem with medium+ sized Parquet files. Workarounds for avoiding the cache are documented in the linked discussion (observablehq/framework discussions/1691, mbostock's comment). Treat 'No results' after refresh as a cache problem first.