Re: pg_stats and range statistics

From: Egor Rogov <e(dot)rogov(at)postgrespro(dot)ru>
To: "Gregory Stark (as CFM)" <stark(dot)cfm(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>
Cc: Justin Pryzby <pryzby(at)telsasoft(dot)com>, Soumyadeep Chakraborty <soumyadeep2007(at)gmail(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: pg_stats and range statistics
Date: 2023-03-20 19:54:24
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On 20.03.2023 22:27, Gregory Stark (as CFM) wrote:
> On Sun, 22 Jan 2023 at 18:22, Tomas Vondra
> <tomas(dot)vondra(at)enterprisedb(dot)com> wrote:
>> I wonder if we have other functions doing something similar, i.e.
>> accepting a polymorphic type and then imposing additional restrictions
>> on it.
> Meh, there's things like array comparison functions that require both
> arguments to be the same kind of arrays. And array_agg that requires
> the elements to be the same type as the state array (ie, same type as
> the first element). Not sure there are any taking just one specific
> type though.
>>> Shouldn't this add some sql tests ?
>> Yeah, I guess we should have a couple tests calling these functions on
>> different range arrays.
>> This reminds me lower()/upper() have some extra rules about handling
>> empty ranges / infinite boundaries etc. These functions should behave
>> consistently (as if we called lower() in a loop) and I'm pretty sure
>> that's not the current state.
> Are we still waiting on these two items? Egor, do you think you'll
> have a chance to work it for this month?

I can try to tidy things up, but I'm not sure if we reached a consensus.

Do we stick with the ranges_upper(anyarray) and ranges_lower(anyarray)
functions? This approach is okay with me. Tomas, have you made up your mind?

Do we want to document these functions? They are very
pg_statistic-specific and won't be useful for end users imo.

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