On 2018-06-29 16:50:47 +0200, Tomas Vondra wrote: > On 06/29/2018 04:00 PM, Mai Peng wrote: > > Hello, > > > > On a pG10.4 instance, my query ( a simple select from a view) throw this > > error: > > ERROR: cannot start subtransactions during a parallel operation > > CONTEXT: PL/pgSQL function check_validity(ltree[]) line 4 during > > statement block entry > > > > So, what does this check_validity function do? It's not part of PostgreSQL, > and it apparently tries to do something that opens a subtransation. Like a > SAVEPOINT for example ... > > > But prefixing this query by "set max_parallel_workers_gather=0" make it > > works. > > > > When I take off the column that is checked by a function, no need to add > > set max_parallel_workers_gather=0 . > > > > Well, that's not really surprising - if you disable parallelism the query is > no longer subject to the restriction about subtransactions. > > > How could I continue to use the default max_parallel_workers_gather (2). > > > > Modity the function not to start a subtransaction.
Wouldn't the right fix be to adjust the parallel safety of the function? Greetings, Andres Freund
