html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,issue,performed_via_github_app
https://github.com/simonw/datasette/issues/526#issuecomment-1258337011,https://api.github.com/repos/simonw/datasette/issues/526,1258337011,IC_kwDOBm6k_c5LALLz,536941,2022-09-26T16:49:48Z,2022-09-26T16:49:48Z,CONTRIBUTOR,"i think the smallest change that gets close to what i want is to change the behavior so that `max_returned_rows` is not applied in the `execute` method when we are are asking for a csv of query.

there are some infelicities for that approach, but i'll make a PR to make it easier to discuss.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",459882902,
https://github.com/simonw/datasette/issues/526#issuecomment-1258167564,https://api.github.com/repos/simonw/datasette/issues/526,1258167564,IC_kwDOBm6k_c5K_h0M,536941,2022-09-26T14:57:44Z,2022-09-26T15:08:36Z,CONTRIBUTOR,"reading the database execute method i have a few questions.

https://github.com/simonw/datasette/blob/cb1e093fd361b758120aefc1a444df02462389a3/datasette/database.py#L229-L242

---
unless i'm missing something (which is very likely!!), the `max_returned_rows` argument doesn't actually offer any protections against running very expensive queries. 

It's not like adding a `LIMIT max_rows` argument. it make sense that it isn't because, the query could already have an `LIMIT` argument. Doing something like `select * from (query) limit {max_returned_rows}` **might** be protective but wouldn't always.

Instead the code executes the full original query, and if still has time it fetches out the first `max_rows + 1` rows. 

this *does* offer some protection of memory exhaustion, as you won't hydrate a huge result set into python (however, there are [data flow patterns](https://github.com/simonw/datasette/issues/1727#issuecomment-1258129113) that could avoid that too)

given the current architecture, i don't see how creating a new connection would be use?

---

If we just removed the `max_return_rows` limitation, then i think most things would be fine **except** for the QueryViews. Right now rendering, just [5000 rows takes a lot of client-side memory](https://github.com/simonw/datasette/issues/1655) so some form of pagination would be required.


","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",459882902,