Re: Surprising dead_tuple_count from pgstattuple

On Tue, 2010-08-10 at 07:43 +0900, Itagaki Takahiro wrote:
> 2010/8/10 Simon Riggs <simon@2ndquadrant.com>:
> > Any SQL statement that reads a block can do HOT pruning, if the block is
> > otherwise unlocked.
> 
> We use the term "HOT" for two features:
>   1. HOT updates: Avoiding index updates when keys are not modified.
>   2. HOT pruning: Removing tuple bodies, that works even for indexed tuples.
> 
> 2 is the point of the case, but ambiguous "HOT" might confuse some people.

Good point. We should say "HOT updates" and "pruning" as separate
techniques. Itagaki invented the pruning technique and deserves much
credit for that.

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Development, 24x7 Support, Training and Services