Don't auto-restart per-database autoprewarm workers.

We should try to prewarm each database only once.  Otherwise, if
prewarming fails for some reason, it will just keep retrying in an
infnite loop.  This can happen if, for example, the database has been
dropped.  The existing code was intended to implement the try-once
behavior, but failed to do so because it neglected to set
worker.bgw_restart_time to BGW_NEVER_RESTART.

Mithun Cy, per a report from Hans Buschmann

Discussion: http://postgr.es/m/CA+hUKGKpQJCWcgyy3QTC9vdn6uKAR_8r__A-MMm2GYfj45caag@mail.gmail.com

diff --git a/contrib/pg_prewarm/autoprewarm.c b/contrib/pg_prewarm/autoprewarm.c
index cc5e2dd89cd48de64d5e9dff6f10104f0596aad7..3bd0010bf8b2c92b1c62c82412ac6a0dd424721e 100644 (file)
--- a/contrib/pg_prewarm/autoprewarm.c
+++ b/contrib/pg_prewarm/autoprewarm.c
@@ -844,6 +844,7 @@ apw_start_database_worker(void)
        worker.bgw_flags =
                BGWORKER_SHMEM_ACCESS | BGWORKER_BACKEND_DATABASE_CONNECTION;
        worker.bgw_start_time = BgWorkerStart_ConsistentState;
+       worker.bgw_restart_time = BGW_NEVER_RESTART;
        strcpy(worker.bgw_library_name, "pg_prewarm");
        strcpy(worker.bgw_function_name, "autoprewarm_database_main");
        strcpy(worker.bgw_name, "autoprewarm worker");