Re: Block-level CRC checks

Greg Stark escribió:

> Writing this explanation did bring to mind one solution which we had  
> already discussed for other reasons: not marking blocks dirty after hint 
> bit setting.

How about when a hint bit is set and the page is not already dirty, set
the checksum to the "always valid" value?  The problem I have with this
idea is that there would be lots of pages excluded from the CRC checks,
a non-trivial percentage of the time.

Maybe we could mix this with Simon's approach to counting hint bit
setting, and calculate a valid CRC on the page every n-th non-logged
change.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.