Re: [HACKERS] Terrible performance on wide selects

Tom Lane kirjutas N, 23.01.2003 kell 02:04:
> "Dann Corbit" <DCorbit@connx.com> writes:
> > Maybe I don't really understand the problem, but it seems simple enough
> > to do it once for the whole query.
>
> We already do cache column offsets when they are fixed.  The code that's
> the problem executes when there's a variable-width column in the table
> --- which means that all columns to its right are not at fixed offsets,
> and have to be scanned for separately in each tuple, AFAICS.

Not only varlen columns, but also NULL columns forbid knowing the
offsets beforehand.

--
Hannu Krosing <hannu@tm.ee>