Re: Block-level CRC checks

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Greg Stark wrote:
>> I'm beginning to think just excluding the hint bits would be simpler and 
>> safer. If we're double buffering then it might be possible to do that 
>> pretty cheaply. Copy the whole buffer with memcpy then loop through the 
>> line pointers unsetting the hint bits. Then do the crc. Though that would 
>> prevent us from doing "zero-copy" crc by doing it in the copy.

> The downside to this idea is that we need to create a copy of the page
> and call those routines when we read the page in, too.

Ugh.  The cost on write was bad enough, but paying it on read is a lot
worse ...
        regards, tom lane