Conrad Ludgate a695713727 [sql-over-http] Reset session state between pooled connection re-use (#12681) ...

Session variables can be set during one sql-over-http query and observed
on another when that pooled connection is re-used. To address this we
can use `RESET ALL;` before re-using the connection. LKB-2495

To be on the safe side, we can opt for a full `DISCARD ALL;`, but that
might have performance regressions since it also clears any query plans.
See pgbouncer docs
https://www.pgbouncer.org/config.html#server_reset_query.

`DISCARD ALL` is currently defined as:
```
CLOSE ALL;
SET SESSION AUTHORIZATION DEFAULT;
RESET ALL;
DEALLOCATE ALL;
UNLISTEN *;
SELECT pg_advisory_unlock_all();
DISCARD PLANS;
DISCARD TEMP;
DISCARD SEQUENCES;
```

I've opted to keep everything here except the `DISCARD PLANS`. I've
modified the code so that this query is executed in the background when
a connection is returned to the pool, rather than when taken from the
pool.

This should marginally improve performance for Neon RLS by removing 1
(localhost) round trip. I don't believe that keeping query plans could
be a security concern. It's a potential side channel, but I can't
imagine what you could extract from it.

---

Thanks to
https://github.com/neondatabase/neon/pull/12659#discussion_r2219016205
for probing the idea in my head.

2025-07-23 17:43:43 +00:00

..

src

[sql-over-http] Reset session state between pooled connection re-use (#12681)

2025-07-23 17:43:43 +00:00

Cargo.toml

chore(proxy/tokio-postgres): remove phf from sqlstate and switch to tracing (#11249)

2025-03-31 12:35:51 +00:00