On Fri, Mar 31, 2017 at 4:18 PM, Robert Haas <robertmh...@gmail.com> wrote: > On Fri, Mar 31, 2017 at 3:33 AM, Konstantin Knizhnik > <k.knizh...@postgrespro.ru> wrote: >> It is possible to execute query concurrently using SPI? >> If so, how it can be enforced? >> I tried to open cursor with CURSOR_OPT_PARALLEL_OK flag but it doesn't help: >> query is executed by single backend while the same query been launched at >> top level uses parallel plan: >> >> fsstate->portal = SPI_cursor_open_with_args(NULL, fsstate->query, >> fsstate->numParams, argtypes, values, nulls, true, CURSOR_OPT_PARALLEL_OK); >> ... >> SPI_cursor_fetch(fsstate->portal, true, 1); > > Parallel execution isn't possible if you are using a cursor-type > interface, because a parallel query can't be suspended and resumed > like a non-parallel query. If you use a function that executes the > query to completion in one go, like SPI_execute_plan, then it's cool. > See also commit 61c2e1a95f94bb904953a6281ce17a18ac38ee6d. > > --
Adding to that, for your case, passing CURSOR_OPT_PARALLEL_OK is not enough, because PortalRun for the cursor would be having portal->run_once set as false which restricts parallelism in ExecutePlan, if (!execute_once || dest->mydest == DestIntoRel) use_parallel_mode = false; You may check [1] for the discussion on this. [1] https://www.postgresql.org/message-id/flat/CAFiTN-vxhvvi-rMJFOxkGzNaQpf%2BKS76%2Bsu7-sG_NQZGRPJkQg%40mail.gmail.com#cafitn-vxhvvi-rmjfoxkgznaqpf+ks76+su7-sg_nqzgrpj...@mail.gmail.com -- Regards, Rafia Sabih EnterpriseDB: http://www.enterprisedb.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
