Re: [PATCH] backend: compare word-at-a-time in bcTruelen

On Tue, 2009-06-16 at 10:23 -0400, Tom Lane wrote:

> Speaking of which, what about some performance numbers?  Like Heikki,
> I'm quite suspicious of whether there is any real-world gain to be had
> from this approach.

It has been "lore" for some time that VARCHAR is cheaper than
VARCHAR(n), so I'm looking forward to this improvement as a real-world
gain. (If done right).

I've looked at the code and the thing that bothers me is that I can't
see where or why bcTruelen would be called more often for VARCHAR(n)
than it would be for VARCHAR, on a Select/Sort only workload.

Are we tuning the right thing? Is there some code we can completely
avoid?

If not, does this mean it is a generic effect? Does this imply that
NUMERIC(n) is somehow worse than NUMERIC? etc..

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