Parquet queries stop returning results after refresh on Windows

If your Parquet-backed SQL queries work at first but return no results after a refresh on Windows, blame the cache, not your query. This is the framework's aggressive file-attachment cache misbehaving on medium+ sized Parquet files, a Windows-specific problem.

1. Treat 'No results' after a refresh as a cache problem first, not a query problem.
2. Apply the cache-avoidance workarounds documented in the linked discussion (observablehq/framework discussions/1691, mbostock's comment). Expected: queries return results again after refresh.

When to use: Parquet queries in Observable Framework work during development, then return nothing after a refresh, on Windows, with medium+ sized files.

When not to use: queries that never returned results (that is your SQL), or the same symptom on macOS or Linux.

Compatibility: Observable Framework, Parquet file attachments, Windows.

Variants:

• "observable framework parquet no results after refresh"
• "parquet queries stop returning results windows"
• "observable file attachment cache parquet"

Root cause: the framework's aggressive file-attachment cache goes stale on medium+ sized Parquet files on Windows.

Edge cases: small Parquet files dont seem to trigger it. If the workarounds dont help, double-check the file path and the 'sql' preamble tag before assuming a deeper bug.

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.