In postgres_fdw, once remote connections are established, they are cached and re-used for subsequent queries and transactions. There can be some cases where those cached connections are unavaiable, for example, by the restart of remote server. In these cases, previously an error was reported and the query accessing to remote server failed if new remote transaction failed to start because the cached connection was broken.
This commit improves postgres_fdw so that new connection is remade if broken connection is detected when starting new remote transaction. This is useful to avoid unnecessary failure of queries when connection is broken but can be reestablished.
Author: Bharath Rupireddy, tweaked a bit by Fujii Masao
32a9c0bdf4 postgres_fdw: reestablish new connection if cached one is detected as broken.
contrib/postgres_fdw/connection.c | 54 ++++++++++++++++++++------
contrib/postgres_fdw/expected/postgres_fdw.out | 48 +++++++++++++++++++++++
contrib/postgres_fdw/sql/postgres_fdw.sql | 41 +++++++++++++++++++
3 files changed, 131 insertions(+), 12 deletions(-)