Oracle 11g XE, Apex 4.2.3 with DG4ODBC connecting to MSSQL Express on Windows 7.
The above configuration gives poor performance (slow or no response).
Simple queries work - "select itemname from tablea@dblink"
Minor complex queries (and above ??) do not work - "select a.itemname from tablea@dblink a, tableb@dblink b where a.id=b.id"
Important other information:
On the same machine there is a Windows 7 VM running with Oracle 10g XE, Apex 4.1.1- with HSODBC connecting to the MSSQL Express on the host.
The application has a page with multiple regions and more complex queries (join, count, in list) and it loads normally.
There are none of the issues experienced with the 11g/4.2 mix.
Is there a tweak/patch to make the 11g/4.2 function as well as the 10g/4.1 (will settle for equal performance) ?
Sounds like there are lots of moving parts there.
All bits running on the same host? Hope its got plenty of memory ... using NAT or a bridging setup for the VM NIC(s)?
So in the XE guest, there is a tnsalias with an ...HS=OK... stanza? And listener running at the Express host with the dg4odbc setup?
Is there much difference in timing for a tnsping <tnsalias> and a sqlplus ... conn <user>@tnsalias with set timing on?