Re: How to run a task continuously in the background

We used a trigger that called pg_notify (https://www.postgresql.org/docs/9.5/sql-notify.html?) and then had another

process that LISTENed for notifications.

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Gerard Weatherby| Application Architect
NMRbox | Department of Molecular Biology and Biophysics | UConn Health
263 Farmington Avenue, Farmington, CT 06030-6406
Phone: 860 679 8484
uchc.edu
________________________________
From: Dirk Mika <Dirk(dot)Mika(at)mikatiming(dot)de>
Sent: Tuesday, July 16, 2019 1:32 AM
To: pgsql-general(at)lists(dot)postgresql(dot)org
Subject: Re: How to run a task continuously in the background

Creating a background worker that invokes a stored procedure once per
second? <https://www.postgresql.org/docs/11/bgworker.html<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.postgresql.org_docs_11_bgworker.html&d=DwMGaQ&c=EZxp_D7cDnouwj5YEFHgXuSKoUq2zVQZ_7Fw9yfotck&r=f-X3XMK2s9o3QbCr8_n2sYw801ckLPRVRmiIoBpOKHg&m=--Q0KrfGCflvz0nQ-nVc0aEVt7HWE4zo7tjxzoXIKTg&s=Vem581EECRyjgEXTrLv2sXtILmQGDJaKvWQ3XWy8OBQ&e=>>
But this is not so simple to put in place.

It's not really important that the job runs once a second, but that it starts immediately when I want it to.
If I start a job with pg_cron, it will not be executed until the next full minute at the earliest.

Otherwise pg_cron with a function that performs a pg_sleep of one
second in a loop.

Anyway, it seems to me you are better refactoring your solution: it
seems you need to process data when _new data_ comes, not once per
second, so it sounds to me like a trigger could solve the problem.

The processing of the data via a job is deliberately chosen so as to separate the insertion of the data from their processing.
If a trigger were to do this, the transaction in which the data is inserted would take longer. This is not intended.
It is common for many records to be inserted in a short time, but processing takes a little time. The application that inserts the data should however not be slowed down.

Dirk
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