Re: Fractions in GUC variables

From: Peter Eisentraut <peter_e(at)gmx(dot)net>
To: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, John Gorman <johngorman2(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Fractions in GUC variables
Date: 2014-12-15 15:19:19
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On 12/15/14 8:56 AM, Heikki Linnakangas wrote:
>> show cursor_tuple_fraction; --> 10%
>> set cursor_tuple_fraction = .15; --> 15%
>> set cursor_tuple_fraction = '33%'; --> 33%
>> I tagged four configuration variables to display as percents.
> I'm not sure I agree that percentages are better than fractions. I'd
> vote a -0.5 for changing the default display format. There isn't much
> harm in accepting them as a secondary format, though.

Agreed with not changing the default output. Everyone is used to it,
and there is no reason why the percent output would be intrinsically better.

> We should only accept percentages for settings where that makes sense.
> It is sensible for most of the PGC_REAL settings, but not so much for
> geqo_selection_bias or seed, for example.

Right. But then this feature would get more complicated, as opposed to
supposedly making things simpler.

> Overall, I feel that this isn't really worth the trouble. We use
> fractions consistently now, so there isn't much room for confusion over
> what the current values mean. Using a percentage might be more familiar
> for some people, but OTOH you'll have to get used to the fractions
> anyway, unless we change the default output format too, and I'm not in
> favour of doing that. I suggest that we just drop this, and remove the
> TODO item.


The patch is sound as far as it goes (I might be inclined to accept
whitespace between number and % sign), but given the above points and
the original reason for it having been eliminated, I'm inclined to drop it.

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