Re: Does frequent update of a row affects performance

On 04/26/2016 05:55 AM, Rakesh Kumar wrote:
> Pardon me if this has been discussed before.
>
> I believe that PG back-end does not version index rows the way it does
> the data rows. Assume that the app updates a row frequently (several
> times in a second). For each update, PG will create a new version.
> However I believe the primary key index pointing to that row will point
> to only the first row and the back end has to work its way traversing
> the list until it finds the appropriate row matching the xmin/xmax.
> Does frequent vaccum take care of this by removing the dead rows and
> hence reducing the commute.

Might want to take a look at:

http://www.postgresql.org/docs/9.5/interactive/indexam.html

>
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com