Re: ODBC cliens is hanging if network connection is broken

Hello PostgreSQL Community!

I downloaded and installed the latest version of PostgreSQL from https://www.postgresql.org/ftp/source/v10.4/ on my SLES 12 system.
Here is my configuration of unixODBC:

odbcinst,ini
[PostgreSQL]
Description=PostgreSQL ODBC driver
Driver=/usr/local/lib/psqlodbcw.so
FileUsage=1

odbc.ini
[sles12-1]
Description = PostgreSQL connection to rtpdb
Driver = PostgreSQL
Database = rtpdb
Servername = sles12-1
Username =
Password =
Port = 5432
Protocol = 7.4+
ReadOnly = No
RowVersioning = No
ShowSystemTables = No
ConnSettings =

As a Driver in odbcinst.ini I specified the path to psqlodbcw.so which was downloaded from https://git.postgresql.org/gitweb/?p=psqlodbc.git and built as follows:
./configure
make
make install

Could you please provide a comment concerning the following situation?

I  created a simple ODBC program which calls "SELECT pg_is_in_recovery()" on the remote PostgreSQL server using ODBC API. It works good with this ODBC configuration. But as soon as I turn off network interface after SQLConnect  call and before SQLExecDirect, it leads to SQLExecDirect hanging.

I tried to use statement_timeout  and idle_in_transaction_session_timeout  postgresql configuration parameters but they were not suitable for network issue case. These parameters define server-side behaviour but a client considers that the connection is ok and it is hanging.

As far as I know SQL_ATTR_CONNECTION_TIMEOUT ODBC attribute could handle this situation. Another ODBC driver for another database in case of similar situation returns HYT01  ODBC error (Connection timeout expired) . But I guess  SQL_ATTR_CONNECTION_TIMEOUT  is not supported by psqlodbc.  Am I right?

PostgreSQL JDBC driver provides socketTimeout property which helps a client to be informed about network problems and to avoid an infinite hanging.
In my tests it returned 08006 sqlstate (connection_failure ).

So I have a question. Is there any psqlodbc or native PostgreSQL mechanism or configuration parameter which helps a client to be informed about network problem?
Is there any mechanism which helps to avoid this infinite hanging for SQL query in this case?

Thank You in advance,
Andrei Yahorau