Re: texteq/byteaeq: avoid detoast [REVIEW] - Mailing list pgsql-hackers

From Tom Lane
Subject Re: texteq/byteaeq: avoid detoast [REVIEW]
Date
Msg-id 11083.1295367302@sss.pgh.pa.us
Whole thread Raw
In response to Re: texteq/byteaeq: avoid detoast [REVIEW]  (Itagaki Takahiro <itagaki.takahiro@gmail.com>)
Responses Re: texteq/byteaeq: avoid detoast [REVIEW]  (Robert Haas <robertmhaas@gmail.com>)
List 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


pgsql-hackers by date:

Previous
From: Tom Lane
Date:
Subject: Re: Replication logging
Next
From: Tom Lane
Date:
Subject: Re: pg_basebackup for streaming base backups