From: Justin Pryzby <pryzby@telsasoft.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Alexander Korotkov <a.korotkov@postgrespro.ru>
Cc: David Steele <david@pgmasters.net>
Cc: Ildus Kurbangaliev <i.kurbangaliev@gmail.com>
Cc: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: [HACKERS] Custom compression methods
Date: Sat, 20 Mar 2021 10:39:34 -0500
Message-ID: <20210320153933.GT11765@telsasoft.com> (raw)
In-Reply-To: <CAFiTN-uX=hLscjL=0raA6dYcoiZB=9YqL3DmX15CMvZiu+WB+w@mail.gmail.com>
References: <20210319222242.GA23930@alvherre.pgsql>
<CA+TgmoYQ8hn1apJXbmxutYv-sHkTOUdPxdFJUzvZ7uT4cUT+cQ@mail.gmail.com>
<CA+TgmobGm9umTgno4O4UqSAoGhOPOAA55uiKE8N_wehnHfg4Tw@mail.gmail.com>
<4158590.1616185209@sss.pgh.pa.us>
<20210320000625.GP11765@telsasoft.com>
<20210320074420.GR11765@telsasoft.com>
<CAFiTN-uX=hLscjL=0raA6dYcoiZB=9YqL3DmX15CMvZiu+WB+w@mail.gmail.com>
On Sat, Mar 20, 2021 at 04:37:53PM +0530, Dilip Kumar wrote:
> - 0006 is fine but not sure what is the advantage over what we have today?
The advantage is that it's dozens of lines shorter, and automatically includes
a HINT.
SET default_toast_compression = 'I do not exist compression';
ERROR: invalid value for parameter "default_toast_compression": "I do not exist compression"
-DETAIL: Compression method "I do not exist compression" does not exist.
+HINT: Available values: pglz, lz4.
If we use a GUC hook, I think it should be to special case lz4 to say:
"..must be enabled when PG was built".
> - And, 0008 and 0009, I think my
> 0001-Fixup-dump-toast-compression-method.patch[1] is doing this in a
> much simpler way, please have a look and let me know if you think that
> has any problems and we need to do the way you are doing here?
I tested and saw that your patch doesn't output "SET default_toast_compression"
in non-text dumps (pg_dump -Fc). Also, I think the internal newline should be
removed:
ALTER TABLE public.t ALTER COLUMN b
SET COMPRESSION lz4;
--
Justin
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To: pgsql-hackers@postgresql.org
Cc: pryzby@telsasoft.com, dilipbalaut@gmail.com, tgl@sss.pgh.pa.us, robertmhaas@gmail.com, alvherre@alvh.no-ip.org, andres@anarazel.de, tomas.vondra@2ndquadrant.com, a.korotkov@postgrespro.ru, david@pgmasters.net, i.kurbangaliev@gmail.com, 9erthalion6@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: [HACKERS] Custom compression methods
In-Reply-To: <20210320153933.GT11765@telsasoft.com>
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