Re: Cost of XLogInsert CRC calculations

On Mon, 2005-03-07 at 20:50 -0500, Tom Lane wrote:
> Simon Riggs <simon@2ndquadrant.com> writes:
> > Well, we're using the CRC in 3 separate places...
> > (1) for xlog records
> > (2) for complete blocks copied to xlog
> > (3) for control files
> 
> > For (1), records are so short that probably CRC16 would be sufficient
> > without increasing the error rate noticeably.
> 
> > I think I'd like to keep (3) at CRC64...its just too important. Plus
> > thats slightly less code to change.
> 
> The control files are so short that CRC16 would be plenty.
> 
> > My money is on (2) being the source of most of that run-time anyway,
> 
> Undoubtedly, so there's not going to be much win from micro-optimization
> by having several different CRC functions.  

Agreed.

> I would go for CRC32 across
> the board, myself.

Sold.

Best Regards, Simon Riggs