Re: Read-ahead and parallelism in redo recovery

On Feb 29, 2008, at 8:10 AM, Florian Weimer wrote:
> In the end, I wouldn't be surprised if for most loads, cache warming
> effects dominated recovery times, at least when the machine is not
> starved on RAM.


Uh... that's exactly what all the synchronous reads are doing...  
warming the cache. And synchronous reads are only fast if the system  
understands what's going on and reads a good chunk of data in at  
once. I don't know that that happens.

Perhaps a good short-term measure would be to have recovery allocate  
a 16M buffer and read in entire xlog files at once.
-- 
Decibel!, aka Jim C. Nasby, Database Architect  decibel@decibel.org
Give your computer some brain candy! www.distributed.net Team #1828