Horton

Re: texteq/byteaeq: avoid detoast [REVIEW]

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Itagaki Takahiro <itagaki.takahiro@gmail.com>
Cc: Magnus Hagander <magnus@hagander.net>, KaiGai Kohei <kaigai@ak.jp.nec.com>, Andy Colson <andy@squeakycode.net>, Noah Misch <noah@leadboat.com>, pgsql-hackers@postgresql.org
Date: 2011-01-18T16:15:02Z
Lists: pgsql-hackers 
Itagaki Takahiro <itagaki.takahiro@gmail.com> writes:
> On Tue, Jan 18, 2011 at 05:39, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I haven't looked at this patch, but it seems to me that it would be
>> reasonable to conclude A != B if the va_extsize values in the toast
>> pointers don't agree.

> It's a very light-weight alternative of memcmp the byte data,
> but there is still the same issue -- we might have different
> compressed results if we use different algorithm for TOASTing.

Which makes it a lightweight waste of cycles.

> So, it would be better to apply the present patch as-is.

No, I don't think so.  Has any evidence been submitted that that part of
the patch is of benefit?

			regards, tom lane