On Sun, Jan 17, 2016 at 11:09 PM, Masahiko Sawada <sawada.m...@gmail.com> wrote: > On Wed, Jan 13, 2016 at 1:54 AM, Alvaro Herrera wrote: > * Confirm value of pg_stat_replication.sync_state (sync, async or potential) > * Confirm that the data is synchronously replicated to multiple > standbys in same cases. > * case 1 : The standby which is not listed in s_s_name, is down > * case 2 : The standby which is listed in s_s_names but potential > standby, is down > * case 3 : The standby which is considered as sync standby, is down. > * Standby promotion > > In order to confirm that the commit isn't done in case #3 forever > unless new sync standby is up, I think we need the framework that > cancels executing query. > That is, what I'm planning is, > 1. Set up master server (s_s_name = '2, standby1, standby2) > 2. Set up two standby servers > 3. Standby1 is down > 4. Create some contents on master (But transaction is not committed) > 5. Cancel the #4 query. (Also confirm that the flush location of only > standby2 makes progress)
This will need some thinking and is not as easy as it sounds. There is no way to hold on a connection after executing a query in the current TAP infrastructure. You are just mentioning case 3, but actually cases 1 and 2 are falling into the same need: if there is a failure we want to be able to not be stuck in the test forever and have a way to cancel a query execution at will. TAP uses psql -c to execute any sql queries, but we would need something that is far lower-level, and that would be basically using the perl driver for Postgres or an equivalent here. Honestly for those tests I just thought that we could get to something reliable by just looking at how each sync replication setup reflects in pg_stat_replication as the flow is really getting complicated, giving to the user a clear representation at SQL level of what is actually occurring in the server depending on the configuration used being important here. -- Michael -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
