Re: Determine potential change in table size after a column dropped?

Am 01.02.22 um 14:46 schrieb Jiankang Ji:

Hi All Supermen Experts,

I'm new in pgsql and have a similar problem for a timescale pgDB. A DB table is for storing raw sessions data received through IoT network from many remote machines. The data format is the same for all the machines but the sessions lasting-periods could be different from 1 minute to 1 hour and such. Each machine could be activated once a day or a few times a day randomly.

My question is:

1. How to setup a watch-dog to detect new data has been added into the DB, and 

2. How to pick-up the newly completed sessions data since last pick-up and put it into a buffer table dedicated to new data for further ETL processing?

If you have some scripts in pgSQL, Python or C, it will be greatly appreciated!

Thank you.

Best regards, Ji

In order to get notified should new rows arrive (or current ones updated or deleted), you can install a trigger which fires a NOTIFY command on a name (channel).

All other sessions which have issued a LISTEN on the same name (channel) will receive a notification.

Unfortunately, not all languages and drivers support this.

Recently, I updated the code for pg_listen in the script language Tcl. It's committed, but no new version released yet.

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