Re: What exactly is our CRC algorithm?

On 11/07/2014 07:08 AM, Amit Kapila wrote:
> On Tue, Nov 4, 2014 at 3:17 PM, Heikki Linnakangas <hlinnakangas@vmware.com>
> wrote:
>
>> On 10/27/2014 06:02 PM, Heikki Linnakangas wrote:
>>
>>> I came up with the attached patches. They do three things:
>>>
>>> 1. Get rid of the 64-bit CRC code. It's not used for anything, and
>>> haven't been for years, so it doesn't seem worth spending any effort to
>>> fix them.
>>>
>>> 2. Switch to CRC-32C (Castagnoli) for WAL and other places that don't
>>> need to remain compatible across major versions.
>>>
>>>
> Will this change allow database created before this commit to be
> started after this commit?

No. You could use pg_resetxlog to fix the WAL, but I think at least 
relmap files would still prevent you from starting up. You could use 
pg_upgrade.

- Heikki