Re: Page Checksums + Double Writes

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "Jeff Janes" <jeff(dot)janes(at)gmail(dot)com>, "Robert Haas" <robertmhaas(at)gmail(dot)com>
Cc: "Simon Riggs" <simon(at)2ndquadrant(dot)com>, <alvherre(at)commandprompt(dot)com>,<david(at)fetter(dot)org>, <pgsql-hackers(at)postgresql(dot)org>, <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: Page Checksums + Double Writes
Date: 2011-12-23 20:23:54
Message-ID: 4EF48EFA02000025000440CC@gw.wicourts.gov
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:

> Could we get some major OLTP users to post their CLOG for
> analysis? I wouldn't think there would be much
> security/propietary issues with CLOG data.

FWIW, I got the raw numbers to do my quick check using this Ruby
script (put together for me by Peter Brant). If it is of any use to
anyone else, feel free to use it and/or post any enhanced versions
of it.

#!/usr/bin/env ruby

Dir.glob("*") do |file_name|
contents = File.read(file_name)
total =
contents.enum_for(:each_byte).enum_for(:each_slice,
256).inject(0) do |count, chunk|
if chunk.all? { |b| b == 0x55 }
count + 1
else
count
end
end
printf "%s %d\n", file_name, total
end

-Kevin

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Tom Lane 2011-12-23 20:25:57 Re: Page Checksums + Double Writes
Previous Message Kevin Grittner 2011-12-23 20:06:56 Re: Page Checksums + Double Writes