Re: EXPLAIN and nfiltered

On 2010-11-18 6:44 PM +0200, Andres Freund wrote:
> On Thursday 18 November 2010 16:45:23 Marko Tiikkaja wrote:
>> Here's a patch for showing in EXPLAIN ANALYZE the number of rows a plan
>> qual filtered from a node's input.  The output looks like this:
> If it supports the same for index-scans I *really* like it and even proposed a
> patch earlier (4A16A8AF.2080508@anarazel.de)
> I still find myself constantly wishing to have something like that...
> Especially when wondering if it might be worthwile to add another column
> (which is implemented as an additional qual atm) should get included in a
> multiicolumn index.
>
> It was shot down at the time because it might break some explain-parsers
> expectations. Imho that argument is less valid these days.

I have to admit, I didn't query the archives before looking at this.  I 
guess I should have.  This patch supports all Scan nodes, and I think 
that's the right thing to do.

I agree 100% that breaking the parseability (is that a word?) of the 
EXPLAIN output is not really an argument these days, so we might want to 
give this some thought.


Regards,
Marko Tiikkaja