From: Justin Pryzby <pryzby@telsasoft.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@postgresql.org, Dilip Kumar <dilipbalaut@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Subject: Re: Move pg_attribute.attcompression to earlier in struct for reduced size?
Date: Thu, 27 May 2021 17:10:19 -0500
Message-ID: <20210527221019.GG2082@telsasoft.com> (raw)
In-Reply-To: <20210526013347.GG3676@telsasoft.com>
References: <20210517204803.iyk5wwvwgtjcmc5w@alap3.anarazel.de>
<2854987.1621285592@sss.pgh.pa.us>
<20210517212857.qyk4fxykfbxhmxof@alap3.anarazel.de>
<YKMXVHCoNGZ61E9q@paquier.xyz>
<YKdT5ZM5OInCsDkM@paquier.xyz>
<3962395.1621609263@sss.pgh.pa.us>
<626613.1621787110@sss.pgh.pa.us>
<20210526013347.GG3676@telsasoft.com>
On Tue, May 25, 2021 at 08:33:47PM -0500, Justin Pryzby wrote:
> On Sun, May 23, 2021 at 12:25:10PM -0400, Tom Lane wrote:
> > However, the more I looked at that code the less I liked it.
> > I think the way that compression selection is handled for indexes,
> > ie consult default_toast_compression on-the-fly, is *far* saner
> > than what is currently implemented for tables. So I think we
> > should redefine attcompression as "ID of a compression method
> > to use, or \0 to select the prevailing default. Ignored if
> > attstorage does not permit the use of compression".
>
> +1
>
> It reminds me of reltablespace, which is stored as 0 to mean the database's
> default tablespace.
I was surprised to realize that I made this same suggestion last month...
https://www.postgresql.org/message-id/20210320074420.GR11765@telsasoft.com
|..unless we changed attcompression='\0' to mean (for varlena) "the default
|compression". Rather than "resolving" to the default compression at the time
|the table is created, columns without an explicit compression set would "defer"
|to the GUC (of course, that only affects newly-inserted data).
The original reason for that suggestion Michael handled differently in
63db0ac3f9e6bae313da67f640c95c0045b7f0ee
--
Justin
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To: pgsql-hackers@postgresql.org
Cc: pryzby@telsasoft.com, tgl@sss.pgh.pa.us, michael@paquier.xyz, andres@anarazel.de, dilipbalaut@gmail.com, robertmhaas@gmail.com
Subject: Re: Move pg_attribute.attcompression to earlier in struct for reduced size?
In-Reply-To: <20210527221019.GG2082@telsasoft.com>
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