Re: [cx-oracle-users] How to deal with lost connection to Oracle ?

[Christopher J. <chr...@or...>]

On 07/21/2010 10:50 AM, Anthony Tuininga wrote:

>>> On Wed, Jul 21, 2010 at 7:14 AM,<prz...@po...>  wrote:

>>>> Each Oracle has its own backup time. What I need is to
>>>> properly handle lost connections , e.g.:
>>>> minute 1: fetch data
>>>> minute 2: fetch data
>>>> minute 3: fetch data
>>>> minute 4: lost connection [1] (how to detect it ?) - backup started
>>>> minute 5: try to connect - failed [2] (how to detect it ?) - ongoing backup process
>>>> minute 6: try to connect - failed ...
>>>> minute 7: try to connect - failed ...
>>>> minute 8: try to connect - failed ...
>>>> minute 9: try to connect - successful ...
>>>> minute10: fetch data
>>>>
>>>> How can I detect [1] and [2] ?
>>>
>>> It depends what version of Oracle you are using. For 10.2 and up you
>>> can use connection.ping() which will attempt to contact the server and
>>> raise an error if the connection has dropped.
>>>
>>> try:
>>>      connection.ping()

If you (i) can't use ping (ii) find its internal implementation
doesn't catch everything you classify as a connection error (iii) or
don't want to use it because it causes a roundtrip to the DB and hence
reduces scalability, then you could try explicitly testing error
codes.  A fairly good set of codes to identify if an error is a
connection error is given in the PHP_OCI_HANDLE_ERROR macro used by
PHP error checking.  See
http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3/ext/oci8/php_oci8_int.h?view=markup
There's an OCI attribute check (also used in PHP_OCI_HANDLE_ERROR)
that does this test but cx_Oracle doesn't expose it.

Chris

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online Oracle Tuxedo training event includes a hands-on Python lab.
Learn more at http://www.oracle.com/goto/otnvdd
The American-time zone lab is tomorrow.


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