Postgres Pro
Downloads
Home   >   mailing lists

Re: Does PostgreSQL cache all columns of a table after SELECT? - Mailing list pgsql-novice

From David G. Johnston
Subject Re: Does PostgreSQL cache all columns of a table after SELECT?
Date
Msg-id CAKFQuwa-KCHhYi5Z5LKBK+H2H84G7S-dZVqZy-AH3gRUanexnA@mail.gmail.com
Whole thread Raw
In response to Re: Does PostgreSQL cache all columns of a table after SELECT?  (Tim Schwenke <tim@trallnag.com>)
Responses Re: Does PostgreSQL cache all columns of a table after SELECT?  (Tim Schwenke <tim@trallnag.com>)
List pgsql-novice
Tree view
On Mon, Jun 5, 2023, 06:17 Tim Schwenke <tim@trallnag.com> wrote:
Hello David,

from what I understand, in PostgreSQL, tables are stored in one or more files called segments. There is no separation by columns.

https://www.postgresql.org/docs/8.1/storage.html

This means if I select a single column from a table the first time, the full file / segment is read and put into page cache if there is enough space.

Pages are subsegment.

You may also wish to take care to notice the version of documentation pages you look at and reference.  8.1 is long past its expiration date.

David J.

pgsql-novice by date:

Previous
From: Laurenz Albe
Date:
Subject: Re: Does PostgreSQL cache all columns of a table after SELECT?
Next
From: Tim Schwenke
Date:
Subject: Re: Does PostgreSQL cache all columns of a table after SELECT?