Re: Optimize crash recovery

On 2020-Mar-13, Thunder wrote:

> Hello hackers：
> 
> 
> During crash recovery, we compare most of the lsn of xlog record with page lsn to determine if the record has already
beenreplayed.
 
> The exceptions are full-page and init-page xlog records.
> It's restored if the xlog record includes a full-page image of the page.
> And it initializes the page if the xlog record include init page information.
> 
> 
> When we enable checksum for the page and verify page success, can we
> compare the page lsn with the lsn of full-page xlog record or init
> page xlog record to detemine it  has already been replayed?

In order to verify that the checksum passes, you have to read the page
first.  So what are you optimizing?

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services