limit select queries via session properties

[paragor]

In our company we use trino with redash.
Sometimes people try to fetch large dataset from trino and it is crash redash. Because redash try to persist all query result to postgresql.

There is issue getredash/redash#7309 for redash. But due complex query in trino (with CTE, UNIONs, etc...) it will not be work for all cases (see trick for detect select query in redash https://github.com/getredash/redash/blob/2776992101a93ef205daee4cc6bc68c42d77f114/redash/query_runner/__init__.py#L294).

So i suggest to add new properties for session that add can force limit for select queries.

I think this is will be useful for another dashboards system too (like grafana, tableau).

[wendigo]

@martint is this something we can consider to implement?

[raunaqmorarka]

I didn't find clear examples where other engines have added the ability to inject a LIMIT clause automatically into the submitted query. It seems common practise to do this in the client submitting the query or through some proxy sits between client and the engine (pg_rewrite).

[paragor]

clickhouse for example https://clickhouse.com/docs/operations/settings/query-complexity#setting-max_result_rows