Re: OCI sends duplicate TNS packet to Oracle server ?

"Srinivas B.S.S" <bsssrinivas_at_lycos.co.uk> wrote:

>Hi,
>
>I am working with ODBC driver which uses OCI calls to interact
>with Oracle on Solaris. Oracle version is 8.1.6. When the
>following query:
>
>"select col1 from tab1 where n=?"
>
>is executed via ODBC with 'xyz' to the bind variable, it causes
>the following packet transaction over the network(obtained from
>sniffing packets at Oracle server on port 1521)
>
>1. Connection establishment packets between ODBC client and
> Oracle server
>2. Request(TNS) from ODBC client with the data "select col1
> from tab1 where n=:P0......" Note that no value has been
> sent for the bind variable.
>3. Response(TNS) from Oracle server with no data for the
> request sent in step 2.
>4. Request(TNS) from ODBC client with the data "select col1
> from tab1 where n=:P0 xyz"
>5. Response(TNS) from Oracle server with valid data for the
> request sent in step 4.
>[...]
>
>Why a dummy TNS request in step 2 is being sent from ODBC ?
>Is there anything that could cause this scenario in OCI(ODBC
>driver which I am using is written in OCI) ?
>
>Has any one observed this behavior earlier ? Any ideas to
>overcome ?
>
>Thanks,
>Srinivas.

I this is what is happening:
The Parser step in processing a SqlPlus request is probably checking for the existence of a usable cached version of your query which,since it is pre-parsed and will be faster, it will use instead of reparsing yours...If it does not find one ( using the 'template' it sent) it returns for your version of the query.

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