Re: Units in postgresql.conf

Peter Eisentraut wrote:
> One frequent source of confusion are the different units that the parameters
> in postgresql.conf use. shared_buffers is in 8 kB, work_mem is in 1 kB;
> bgwriter_delay is in milliseconds, checkpoint_warning is in seconds.
> Obviously, we can't change that without inconveniencing a lot of users.
>
> I think it would be useful to allow units to be added to these settings, for
> example
>
> shared_buffers = 1000kB
> checkpoint_warning = 30s
>
> This would also allow
>
> shared_buffers = 512MB
>
> which is a bit cumbersome to calculate right now (you'd need = 65536).
>
> I haven't thought yet how to parse or implement this, but would people find
> this useful?
>

It is good idea. I going to implement this. There is some proposal:

Time units is easy:
1h = 60min = 3600s = 3600000ms

Memory units:
What kind of unit prefix will we use for memory? 1kB=1000B and
1kiBi=1024B or 1kB=1024kB. See
http://en.wikipedia.org/wiki/Binary_prefix for detail. I suggest use IEC
standard convention. By my opinion it is much better.

And there are some other questions:
1) will be unit required? What will be default unit for value without unit?

I suggest mandatory unit avoid the problem with unclear default value.

2) Each internal representation of setting use different unit. Shell I
convert this representation to milliseconds and bytes? I think it is not
good idea. It should generate some overflow. I suggest to recompute
value and round it to integer.

Zdenek