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From: Tom Lane <[email protected]>
To: Scott Ribe <[email protected]>
Cc: Pgsql-admin <[email protected]>
Subject: Re: update behavior
Date: Thu, 19 Jun 2025 13:35:37 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

Scott Ribe <[email protected]> writes:
> I believe that if I UPDATE a row with the same values that it already has, this still dirties pages, writes the row, generates a WAL entry. There is no shortcut in the processing that's "hey, there's not really a change here, we'll just leave storage alone".

> Is this correct?

It is.  We do offer a trigger you can add to suppress zero-change
updates [1], but that's not the default behavior.  We judged that
checking for that would add more cycles than it removes, for most
applications most of the time.

			regards, tom lane

[1] https://www.postgresql.org/docs/current/functions-trigger.html

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