Accessing a database via AJAX scripts - Mailing list pgsql-general

From Glen Eustace
Subject Accessing a database via AJAX scripts
Date
Msg-id 4C5DE4D2.9040700@godzone.net.nz
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Responses Re: Accessing a database via AJAX scripts
List pgsql-general
I am not sure where my issue lies - apache, perl or postgresql, but as
they say, one has to start somewhere.

My goal is to have a perl cgi script (that is accessed using AJAX)
perform some operations in a database using DBI.  Some of the actions
are likely to take a while so my intent was to have a table that the
backend process periodically writes status messages into.  The front end
web page then uses another AJAX script to watch this table.

I am coming unstuck, the monitoring script works but the backend
processing doesn't.

My first attempts would not show anything at the front end as the
initial response from the backend was not getting through the system
until the backend completely finished (even having set no buffering on
STDOUT).  After googling abit, it would appear that the way around this
is to fork the back-end to allow apache to complete the initial response
and then carry on the processing in the forked child process.
I have opted to use Proc::Daemon to do this. Now I am getting a Pg error
"could not receive data from server: Bad file descriptor".

I have attempted re-opening STDOUT and STDERR in the forked process but
that didn't make any difference.

I am obviously missing something here.  If anyone has done something
similar and has it working I'd appreciate any help I can get.

Glen
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