Re: Improve output of BitmapAnd EXPLAIN ANALYZE

On 10/21/16 12:30 PM, Stephen Frost wrote:
> I don't see why we would want to stick 'N/A' in for the header, even if
> we are reporting the details, when we can provide a pretty reasonable
> number.

Because then it's absolutely clear that we don't have a valid rowcount, 
only a guess (and a guess that's potentially off by a lot).

No one is used to seeing "N/A" in explain, so when they do see it 
they'll immediately realize they don't know what's going on and hit 
google or the docs up. Otherwise they'll just think it's an accurate 
rowcount like for any other node...

> In particular, I certainly don't think we would want to report
> N/A sometimes (lossy case) and then an actual number other times (all
> exact case).  That strikes me as much more likely to be confusing.

Fair enough. I'd certainly rather have a constant N/A then a guess at 
the rowcount.
-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
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