Re: TOASTing smaller things - Mailing list pgsql-hackers

Luke Lonergan wrote:
> I advocate the following:
> 
> - Enable specification of TOAST policy on a per column basis
> 
> As a first step, then:
> 
> - Enable vertical partitioning of tables using per-column specification of
> storage policy.
> 

How are these different from ALTER TABLE SET STORAGE?  They need to be
more specific.

---------------------------------------------------------------------------


> - Luke
> 
> 
> On 3/21/07 1:12 PM, "Bruce Momjian" <bruce@momjian.us> wrote:
> 
> > 
> > Is this a TODO?
> > 
> > ---------------------------------------------------------------------------
> > 
> > Jan Wieck wrote:
> >> On 3/21/2007 2:05 PM, Tom Lane wrote:
> >>> Chris Browne <cbbrowne@acm.org> writes:
> >>>> #define TOAST_DENOMINATOR 17
> >>>>    /* Use this as the divisor; current default behaviour falls from
> >>>> TOAST_DENOMINATOR = 4 */
> >>> 
> >>>> #define TOAST_TUPLE_THRESHOLD^I\
> >>>> ^IMAXALIGN_DOWN((BLCKSZ - \
> >>>> ^I^I^I^I   MAXALIGN(sizeof(PageHeaderData) + 3 * sizeof(ItemIdData))) \
> >>>> ^I^I^I^I  / TOAST_DENOMINATOR)
> >>> 
> >>> Given that you are quoting code that was demonstrably broken since the
> >>> original coding of TOAST up till a month or two back, "it passes
> >>> regression" is not adequate proof of "it's right".  In fact I think
> >>> it's not right; you have not got the roundoff condition straight.
> >>> 
> >>>> 4.  A different mechanism would be to add a fifth storage column
> >>>> strategy (the present four are PLAIN, EXTENDED, EXTERNAL, MAIN), let's
> >>>> say, TOAST.
> >> 
> >> FORCE_COMPRESSION, FORCE_EXTERNAL and FORCE_EXTERNAL_UNCOMPRESSED.
> >> 
> >>> 
> >>> Anything along this line would require invoking the toaster on every
> >>> single tuple, since we'd always have to crawl through all the columns
> >>> to see if toasting was supposed to happen.  No thanks.
> >> 
> >> Not necessarily. A flag in Relation telling if the table has any column
> >> marked like that could be set while constructing the relcache entry.
> >> 
> >>> 
> >>>> Which of these sounds preferable?
> >>> 
> >>> It's a bit late in the cycle to be proposing any of these for 8.3.
> >> 
> >> Certainly.
> >> 
> >> 
> >> Jan
> >> 
> >> -- 
> >> #======================================================================#
> >> # It's easier to get forgiveness for being wrong than for being right. #
> >> # Let's break this rule - forgive me.                                  #
> >> #================================================== JanWieck@Yahoo.com #
> >> 
> >> ---------------------------(end of broadcast)---------------------------
> >> TIP 2: Don't 'kill -9' the postmaster

--  Bruce Momjian  <bruce@momjian.us>          http://momjian.us EnterpriseDB
http://www.enterprisedb.com
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