Re: update on TOAST status'

Jan Wieck <janwieck@t-online.de>

From: JanWieck@t-online.de (Jan Wieck)
To: Bruce Momjian <pgman@candle.pha.pa.us>
Cc: PostgreSQL HACKERS <pgsql-hackers@postgresql.org>
Date: 2000-07-06T21:21:59Z
Lists: pgsql-hackers
Bruce Momjian wrote:
> >     -   VACUUM  doesn't  propagate  ANALYZE  to   TOAST   tables.
> >         Statistics for them are needless because the toast access
> >         is allways hardcoded indexed.
>
> I don't think statistics are insignificant for TOASTed columns.  If I
> say col=3, the optimizer uses that information for estimating the number
> of rows returned, and figuring out the type of join and order of join to
> perform, not just for "use index, don't use index" decisions.

    Ask  your  boys  to give you a training session for "reading"
    when they go to bed tonight - and greet them from the "police
    officer" :-)

    I said "to TOAST tables", not "TOASTed columns".

    Their   master  tables  will  allways  have  the  statistics,
    including those for toasted columns, if you ask for them  via
    ANALYZE.

    In  normal  operation, noone would ever know if a TOAST table
    is accessed during his  query  -  not  even  the  planner  or
    optimmizer.   It's  totally  transparent  and  the  only  one
    accessing the TOAST tables is the toaster himself  -  and  he
    knows what he does.


Jan

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