From: Jan Wieck <janwieck@Yahoo.com>
Message-Id: <200102081250.HAA03586@jupiter.greatbridge.com>
Subject: Re: Re: Postgres and Oracle differences and questions
In-Reply-To: <28278.981560178@sss.pgh.pa.us> from Tom Lane at "Feb 7,
	2001 10:36:18 am"
To: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 8 Feb 2001 07:50:01 -0500 (EST)
CC: Hannu Krosing <hannu@tm.ee>, Jan Wieck <janwieck@Yahoo.com>,
	"D. Johnson" <dspectra@home.com>, pgsql-interfaces@postgreSQL.org
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Tom Lane wrote:
>
> Speaking of which, though, it looks like an update or insert will
> forcibly uncompress (and later recompress) a compressed-in-line datum,
> which seems like a waste of cycles to me.  Jan, shouldn't the test for
> VARATT_IS_EXTENDED at line 357 instead read VARATT_IS_EXTERNAL?

    Not without some more logic added.

    We  don't  have  any  admin  commands yet that can modify the
    toasters strategy on the  attribute  level,  but  the  config
    attributes  in the tuple descriptor are already there. So you
    can tell the toaster  per  attribute  if  it  should  try  to
    compress  or  not,  if it should try to keep the attribute in
    the main tuple harder and  the  like.   You  have  to  modify
    pg_attribute  yourself  for  now, where we might want to have
    some ALTER TABLE, don't we?

    IIRC the above should only be invoked  if  you  do  something
    like  INSERT  ...  SELECT, where the already toasted value is
    coming from  another  tuple  than  the  one  you're  actually
    creating/updating.


Jan

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