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From: Tim Schwenke <[email protected]>
To: pgsql-novice <[email protected]>
Subject: Does PostgreSQL cache all columns of a table after SELECT?
Date: Mon, 05 Jun 2023 14:15:21 +0200
Message-ID: <[email protected]> (raw)

Hello,

I have the following table with the following columns:

large_a: text (few dozen characters up to a few hundred)
large_b: text (few dozen characters up to a few hundred)

The table has several million rows. The DB is running on a large machine.

I perform the following query:

select large_a from table;

The first query takes a few minutes. Afterwards I see that the cache in memory has grown. Next query only takes a few seconds.

What I want to know:

Does the cache also contain large_b? Or is only large_a cached? Assumption is that memory is large enough to fit everything.

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