| From: | "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com> |
|---|---|
| To: | "Andrew Chernow" <ac(at)esilo(dot)com> |
| Cc: | "Aidan Van Dyk" <aidan(at)highrise(dot)ca>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Gregory Stark" <stark(at)enterprisedb(dot)com>, pgsql(at)mohawksoft(dot)com, "Hannu Krosing" <hannu(at)2ndquadrant(dot)com>, Decibel! <decibel(at)decibel(dot)org>, "Alvaro Herrera" <alvherre(at)commandprompt(dot)com>, "Pg Hackers" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Block-level CRC checks |
| Date: | 2008-10-02 14:19:01 |
| Message-ID: | 36e682920810020719g44a7dfd9of46b8fc0e233a718@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Oct 2, 2008 at 10:09 AM, Andrew Chernow <ac(at)esilo(dot)com> wrote:
> I read through this patch and am curious why 0xdeadbeef was used as an
> uninitialized value for the page crc. Is this value somehow less likely to
> have collisons than zero (or any other arbitrary value)?
It was just an arbitrary value I chose to identify non-checksummed
pages; I believe would have the same collision rate as anything else.
> Would it not be better to add a boolean bit or byte to inidcate the crc
> state?
Ideally, though we don't have any spare bits to play with in MAXALIGN=4.
--
Jonah H. Harris, Senior DBA
myYearbook.com
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