Re: Compression of full-page-writes - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Compression of full-page-writes
Date
Msg-id CA+TgmoaVhLrAKvOcsmLVDQyeXBfc77r1gQp_7VX=XCvNz1X5iA@mail.gmail.com
Whole thread Raw
In response to Re: Compression of full-page-writes  (Michael Paquier <michael.paquier@gmail.com>)
Responses Re: Compression of full-page-writes  (Michael Paquier <michael.paquier@gmail.com>)
List pgsql-hackers
On Thu, Dec 11, 2014 at 10:33 PM, Michael Paquier
<michael.paquier@gmail.com> wrote:
> On Tue, Dec 9, 2014 at 4:09 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>> On Sun, Dec 7, 2014 at 9:30 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> > * parameter should be SUSET - it doesn't *need* to be set only at
>> > server start since all records are independent of each other
>>
>> Why not USERSET?  There's no point in trying to prohibit users from
>> doing things that will cause bad performance because they can do that
>> anyway.
>
> Using SUSET or USERSET has a small memory cost: we should
> unconditionally palloc the buffers containing the compressed data
> until WAL is written out. We could always call an equivalent of
> InitXLogInsert when this parameter is updated but that would be
> bug-prone IMO and it does not plead in favor of code simplicity.

I don't understand what you're saying here.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company



pgsql-hackers by date:

Previous
From: Robert Haas
Date:
Subject: Re: PATCH: hashjoin - gracefully increasing NTUP_PER_BUCKET instead of batching
Next
From: Robert Haas
Date:
Subject: Re: [REVIEW] Re: Compression of full-page-writes