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Re: [NOVICE] systable_getnext_ordered

From: yamt(at)mwd(dot)biglobe(dot)ne(dot)jp (YAMAMOTO Takashi)
To: tgl(at)sss(dot)pgh(dot)pa(dot)us
Cc: pgsql-novice(at)postgresql(dot)org, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [NOVICE] systable_getnext_ordered
Date: 2011-02-01 08:35:02
Message-ID: 20110201083502.9215B19D0AE@mail.netbsd.org (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-novice
hi,

thanks for taking a look.

> yamt(at)mwd(dot)biglobe(dot)ne(dot)jp (YAMAMOTO Takashi) writes:
>> the attached patch is to avoid unnecessary detoast'ing and EOF marker pages
>> when possible.  does it make sense?
> 
> The blob page size is already chosen not to allow for out-of-line
> storage, not to mention that pg_largeobject doesn't have a TOAST table.
> So I think avoiding detoasting is largely a waste of time.

doesn't detoasting involve decompression?

> I'm
> unexcited about the other consideration too --- it looks to me like it
> just makes truncation slower, more complicated, and hence more
> bug-prone, in return for a possible speedup that probably nobody will
> ever notice.

slower?  it depends, i guess.

my primary motivation of that part of the patch was to save some space for
certain workloads.  (besides that, leaving unnecessary rows isn't neat,
but it might be a matter of taste.)

YAMAMOTO Takashi

> 
> 			regards, tom lane
> 
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