| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Stephen Frost <sfrost(at)snowman(dot)net> |
| Cc: | Jim Nasby <jim(at)nasby(dot)net>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Andres Freund <andres(at)anarazel(dot)de>, aidan(at)highrise(dot)ca, stark(at)mit(dot)edu, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: 16-bit page checksums for 9.2 |
| Date: | 2012-01-04 15:13:05 |
| Message-ID: | CA+U5nM+L_RFkiSoW7C5rYEaaQkgTnw+P3Y4yhS-S_9n1=+rsKQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Jan 4, 2012 at 1:31 PM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> Simon, all,
>
> * Simon Riggs (simon(at)2ndQuadrant(dot)com) wrote:
>> (1) report all errors on a page, including errors that don't change
>> PostgreSQL data. This involves checksumming long strings of zeroes,
>> which the checksum algorithm can't tell apart from long strings of
>> ones.
>
> Do we actually know when/where it's supposed to be all zeros, and hence
> could we check for that explicitly? If we know what it's supposed to
> be, in order to be consistent with other information, I could certainly
> see value in actually checking that.
Yes, we can. Excellent suggestion, will implement.
That means we can keep the CRC calc fast as well as check the whole of
the page inbound.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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