On Sat, Mar 5, 2016 at 9:25 AM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>> I actually think end-users might well want to use it. Also, I created
>> it by hacking up pg_freespacemap, so it may make sense to have it in
>> the same place.
>> I would also be tempted to add an additional C functions that scan the
>> entire visibility map and return counts of the total number of bits of
>> each type that are set, and similarly for the page level bits.
>> Presumably that would be much faster than
>
> +1.
>
>> I am also tempted to change the API to be a bit more friendly,
>> although I am not sure exactly how. This was a quick and dirty hack
>> so that I could test, but the hardest thing about making it not a
>> quick and dirty hack is probably deciding on a good UI.
>
> Does it mean visibility map API in visibilitymap.c?
Here's an updated patch with an API that I think is much more
reasonable to expose to users, and documentation! It assumes that the
patch I posted a few hours ago to remove PD_ALL_FROZEN will be
accepted; if that falls apart for some reason, I'll update this. I
plan to push this RSN if nobody objects.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company