On Sun, Apr 30, 2023 at 6:35 PM Thomas Munro <thomas.mu...@gmail.com> wrote: > On Sun, Apr 30, 2023 at 4:11 PM Noah Misch <n...@leadboat.com> wrote: > > Speaking of the developer-only status, I find the io_direct name more > > enticing > > than force_parallel_mode, which PostgreSQL renamed due to overuse from > > people > > expecting non-developer benefits. Should this have a name starting with > > debug_? > > Hmm, yeah I think people coming from other databases would be tempted > by it. But, unlike the > please-jam-a-gather-node-on-top-of-the-plan-so-I-can-debug-the-parallel-executor > switch, I think of this thing more like an experimental feature that > is just waiting for more features to make it useful. What about a > warning message about that at startup if it's on?
Something like this? Better words welcome. $ ~/install//bin/postgres -D pgdata -c io_direct=data 2023-05-01 09:44:37.460 NZST [99675] LOG: starting PostgreSQL 16devel on x86_64-unknown-freebsd13.2, compiled by FreeBSD clang version 14.0.5 (https://github.com/llvm/llvm-project.git llvmorg-14.0.5-0-gc12386ae247c), 64-bit 2023-05-01 09:44:37.460 NZST [99675] LOG: listening on IPv6 address "::1", port 5432 2023-05-01 09:44:37.460 NZST [99675] LOG: listening on IPv4 address "127.0.0.1", port 5432 2023-05-01 09:44:37.461 NZST [99675] LOG: listening on Unix socket "/tmp/.s.PGSQL.5432" 2023-05-01 09:44:37.463 NZST [99675] WARNING: io_direct is an experimental setting for developer testing only 2023-05-01 09:44:37.463 NZST [99675] HINT: File I/O may be inefficient or not work on some file systems. 2023-05-01 09:44:37.465 NZST [99678] LOG: database system was shut down at 2023-05-01 09:43:51 NZST 2023-05-01 09:44:37.468 NZST [99675] LOG: database system is ready to accept connections
From a9005129c939a8298c6668645588b2a8ef5064b6 Mon Sep 17 00:00:00 2001 From: Thomas Munro <thomas.mu...@gmail.com> Date: Mon, 1 May 2023 09:46:35 +1200 Subject: [PATCH] Log a warning about io_direct at startup time. We've documented io_direct as an experimental developer-only feature, but that documentation might be hard to find. Let's also display a warning about that in the server log. Later proposals will provide the infrastructure to use it efficiently, but by releasing this switch earlier we can learn about direct I/O quirks in systems in the wild. Discussion: https://postgr.es/m/20230430041106.GA2268796%40rfd.leadboat.com diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index 4c49393fc5..8f5c03fa46 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -1432,6 +1432,12 @@ PostmasterMain(int argc, char *argv[]) errhint("Set the LC_ALL environment variable to a valid locale."))); #endif + /* Temporary warning about experimental status of direct I/O support. */ + if (io_direct_flags != 0) + ereport(WARNING, + (errmsg("io_direct is an experimental setting for developer testing only"), + errhint("File I/O may be inefficient or not work on some file systems."))); + /* * Remember postmaster startup time */ -- 2.40.1
