Thread

Re: Re: [COMMITTERS] pgsql: Adjust OLDSERXID_MAX_PAGE based on BLCKSZ.

Kevin Grittner <kevin.grittner@wicourts.gov> — 2011-07-08T13:45:46Z

Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> wrote:
> On 08.07.2011 15:22, Kevin Grittner wrote:
 
>>    MaxTransactionId / OLDSERXID_ENTRIESPERPAGE
> 
> Hmm, that seems more correct to me anyway. We are trying to
> calculate which page xid MaxTransactionId would be stored on, if
> the SLRU didn't have a size limit. You calculate that with simply
> MaxTransactionId / OLDSERXID_ENTRIESPERPAGE.
 
Good point.  The old calculation was finding the page before the
page which would contain the first out-of-bound entry.  As long as
these numbers are all powers of 2 that's the same, but (besides the
overflow issue) it's not as clear.
 
On the off chance that this saves someone any work, trivial patch
attached.
 
-Kevin