Re: Best way to check for new data.

There are a few ways to do this...thinking about it a bit, I would add a timestamp column to your log table (indexed) and keep a control table which keeps track of the last log print sweep operation.

The print operation would just do
select * from log where logtime > (select lastlogtime());

The idea here is not to have to keep track of anything on the log table like a flag indicating print status, which will cause some bloat issues. All you have to do is reindex once in a while.

lastlogtime() is a function which returns the last log time sweep from the control table. we use a function declared immutable to force planner to treat as a constant (others might tell you to do different here).

Merlin

________________________________________
From: pgsql-performance-owner(at)postgresql(dot)org [mailto:pgsql-performance-owner(at)postgresql(dot)org] On Behalf Of Rodrigo Madera
Sent: Friday, October 28, 2005 5:39 PM
To: pgsql-performance(at)postgresql(dot)org
Subject: [PERFORM] Best way to check for new data.

I have a table that holds entries as in a ficticious table Log(id integer, msg text).
 
Lets say then that I have the program log_tail that has as it´s sole purpose to print newly added data elements.
 
What is the best solution in terms of performace?
 
Thank you for your time,
Rodrigo