Re: [HACKERS] MAIN, Uncompressed? - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] MAIN, Uncompressed?
Date
Msg-id 14901.1503666499@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] MAIN, Uncompressed?  (Simon Riggs <simon@2ndquadrant.com>)
Responses Re: [HACKERS] MAIN, Uncompressed?  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-hackers
Simon Riggs <simon@2ndquadrant.com> writes:
> On 25 August 2017 at 13:21, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> If you know compression isn't useful, but you don't want to fail on
>> wide values, then "external" should serve the purpose.

> Well, almost. External toasts at 2048-ish bytes whereas Main toasts at
> 8160 bytes.
> The rows are typically near 4kB long, so if marked External they would
> always be toasted.
> It's desirable to have the full row in the heap block, rather than
> have to access heap-toastindex-toastblocks in all cases.
> The data is also incompressible, so Main just wastes time on insert.
> Hence, we have a missing option.

Maybe, but the use case seems mighty narrow.
        regards, tom lane



pgsql-hackers by date:

Previous
From: Simon Riggs
Date:
Subject: Re: [HACKERS] MAIN, Uncompressed?
Next
From: Robert Haas
Date:
Subject: Re: [HACKERS] [PATCH] Push limit to sort through a subquery