IS and database connection

I have my IS running on an UNIX box.I have configured by db(Oracle) connection using an OCI driver.The db server is hosted on a different machine.The whole system runs WAN.
The problem is that some times my server log reads as
Connected to database on “” with “LOCAL_TRANSACTION” . it dose not read out the database name that I have configures.Altough this problem gets corrected automatically.
Also I find that when ever this happen the memory usage tends to be high.
What could be the possible reason?