Bonjour Daniel,
When FETCH_COUNT is set, queries combined in a single request don't work as expected: \set FETCH_COUNT 10 select pg_sleep(2) \; select 1; No result is displayed, the pg_sleep(2) is not run, and no error is shown. That's disconcerting.
Indeed.
Does anyone have thoughts about how to fix this?
ATM I don't see a plausible fix that does not involve the parser to store the information that it's a multiple-query command and pass it down somehow to is_select_command().
The lexer (not parser) is called by psql to know where the query stops (i.e. waiting for ";"), so it could indeed know whether there are several queries.
I added some stuff to extract embedded "\;" for pgbench "\cset", which has been removed though, but it is easy to add back a detection of "\;", and also to detect select. If the position of the last select is known, the cursor can be declared in the right place, which would also solve the problem.
Or a more modern approach could be to give up on the cursor-based method in favor of PQsetSingleRowMode().
Hmmm. I'm not sure that row count is available under this mode? ISTM that the FETCH_COUNT stuff should really batch fetching result by this amount.
I'm not sure of the 1 by 1 row approach. -- Fabien.
