TNS Names Alias Cache

Our DBA team keeps a TNSnames.ora file out on a network drive. They maintain it with all the databases anyone would need to connect to. All the developers use this copy of the file to map TNS alias names. Today one developer found out that when he first boots up, our application cannot seem to properly access that file.

The developer said he must first access the network share with Windows Explorer before any of our apps can use the share to get to the TNSnames.ora file. He thinks that maybe Windows need to cache the network share information or something. That did not sound like a sound theory. But the evidence was plain. He said the first time after a reboot, he always get a database not found error. The second time he tries, our apps work fine.

Well there may be some truth to this theory. However he went on to generalize that maybe the users of our system might encounter some problem when cached data is not present, and a database call times out. That just does not seem to have a leg to stand on though.

For starters, we put the TNSnames.ora file on the local C: disk drive of our customer' computers. So there should be no delay in accessing that file. Sure the database server is far away, accessed over the network. However I cannot believe that some delay will cause a timeout resulting in random application errors.