Re: Modifying TOAST thresholds

tgl@sss.pgh.pa.us (Tom Lane) writes:
> Bruce Momjian <bruce@momjian.us> writes:
>> The big question is whether this is for 8.3 or 8.4.
>
> What I would definitely like to see for 8.3 is some performance testing
> done to determine whether we ought to change the current defaults.
> (Both TOAST_TUPLES_PER_PAGE and EXTERN_TUPLES_PER_PAGE ought to be looked
> at.)
>
> Whether it's possible to get the storage parameter in there depends on
> how soon someone produces a patch.  Given that we understand this area
> fairly well, I personally would be willing to give it a pass on the
> "feature freeze" rule, as long as we have the patch by say mid-April.

If I had to end of April, I'd volunteer.  Alas, I will be unavailable
between tomorrow and mid-April.

It seems to me that changing the denominator from 4 to something
somewhat higher (16 comes to mind) would probably be "the patch," and
would likely be useful for a fair number of cases.  I'd really like to
see something like this (e.g. - something that would start TOASTing
for, say, tuples > 500 bytes) in 8.3; this seems to me to have the
potential to be a significant optimization that would be VERY cheap to
implement.  "Low hanging fruit," so to speak.

EDB might like to use this as a route into a tunable "column store"
some time later; I don't think that should stop us from an improvement
today...
-- 
"cbbrowne","@","linuxfinances.info"
http://www3.sympatico.ca/cbbrowne/rdbms.html
"MSDOS didn't get as bad as it  is overnight -- it took over ten years
of careful development."  -- <dmeggins@aix1.uottawa.ca>