Postgres 14 bug breaks mq_poll

[agraven]

Assuming I've diagnosed the issue correctly, bug #16040 in postgres causes mq_poll to fail with error returned from database: query is not a SELECT. Here is the full relevant log snippet from my application:

Oct 02 16:56:25.792  INFO sqlx::query: SELECT * FROM mq_poll($1, …; rows: 0, elapsed: 1.119ms
SELECT
  *
FROM
  mq_poll($1, $2)
  
Oct 02 16:56:25.792 ERROR sqlxmq::runner: Failed to poll for messages: error returned from database: query is not a SELECT

I saw a potential workaround mentioned on Twitter, though I don't know if it's relevant here.

Edit: a fix for the bug has been pushed, so it's presumably just a matter of waiting for that to be released. I'll leave the issue open in case other people encounter it.