On Wed, Jul 8, 2020 at 6:10 PM Bharath Rupireddy <bharath.rupireddyforpostg...@gmail.com> wrote: > > I couldn't think of adding a test case to the existing postgres_fdw > regression test suite with an automated scenario of the remote backend > getting killed.
You could get a backend's PID using PQbackendPID and then kill it by calling pg_terminate_backend() to kill the remote backend to automate scenario of remote backend being killed. > > I would like to thank Ashutosh Bapat (ashutosh.bapat....@gmail.com) > for the suggestion to fix this and the review of my initial patch > attached in [2]. I tried to address the review comments provided on my > initial patch [3]. > > For, one of the Ashutosh's review comments from [3] "the fact that the > same connection may be used by multiple plan nodes", I tried to have > few use cases where there exist joins on two foreign tables on the > same remote server, in a single query, so essentially, the same > connection was used for multiple plan nodes. In this case we avoid > retrying for the second GetConnection() request for the second foreign > table, with the check entry->xact_depth <= 0 , xact_depth after the > first GetConnection() and the first remote query will become 1 and we > don't hit the retry logic and seems like we are safe here. Please add > If I'm missing something here. > > Request the community to consider the patch for further review if the > overall idea seems beneficial. I think this idea will be generally useful if your work on dropping stale connection uses idle_connection_timeout or something like that on the remote server. About the patch. It seems we could just catch the error from begin_remote_xact() in GetConnection() and retry connection if the error is "bad connection". Retrying using PQreset() might be better than calling PQConnect* always. > > [1] > https://www.postgresql.org/message-id/CAExHW5t21B_XPQy_hownm1Qq%3DhMrgOhX%2B8gDj3YEKFvpk%3DVRgw%40mail.gmail.com > [2] > https://www.postgresql.org/message-id/CALj2ACXp6DQ3iLGx5g%2BLgVtGwC4F6K9WzKQJpyR4FfdydQzC_g%40mail.gmail.com > [3] > https://www.postgresql.org/message-id/CAExHW5u3Gyv6Q1BEr6zMg0t%2B59e8c4KMfKVrV3Z%3D4UKKjJ19nQ%40mail.gmail.com > > With Regards, > Bharath Rupireddy. > EnterpriseDB: http://www.enterprisedb.com -- Best Wishes, Ashutosh Bapat
