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In a system like postgres' current heap you cannot know whether it was committed long ago, without actually looking in that side table (or modifying the page the one time you do, to set a hint bit). You pretty fundamentally need something like the transactionid to do so.

Also, in OLTP workload you often have a set of pretty hotly modified data, where you then actually very commonly access recently modified tuples and thus need to do visibility checks.

There's obviously systems with different visibility architectures (either by reducing the types of concurrency allowed, using page level information about recency of modification + something undo based), but given this post is about postgres, I fail to see what you're arguing about here.

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