I struggle to understand why the Halloween Problem is listed as a Postgres issue. The concept that a where condition would run until all rows are condition false is just categorically false for Postgresql.
Yes, and they call it out as a concern, which it isn't with Postgresql.
> This could even cause an infinite loop in some cases where updates continually
place the updated record ahead of the scan performing the update operation.
This just is not true for Postgresql and they don't specify anywhere that they switched from talking about Postgresql to a different database.
So either they believe it's an concern with Postgresql or they aren't being clear when they are talking about different databases.
They didn't call it out as a concern, they said at the beginning of the section "Halloween Problem is a database error that a database system developer needs to be aware of."
To be honest, just like you I also thought that it was related to PostgreSQL or other popular SQL databases somehow, until I re-read the section multiple times.