Re: WIP: BRIN multi-range indexes

On Mon, Jul 13, 2020 at 02:54:56PM +0900, Masahiko Sawada wrote:
>On Mon, 13 Jul 2020 at 09:33, Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
>>
>> On 2020-Jul-13, Tomas Vondra wrote:
>>
>> > On Sun, Jul 12, 2020 at 07:58:54PM -0400, Alvaro Herrera wrote:
>>
>> > > Maybe we can try to handle this with some other function that interprets
>> > > the bytea in 'value' and returns a user-readable text.  I think it'd
>> > > have to be a superuser-only function, because otherwise you could easily
>> > > cause a crash by passing a value of a different opclass.  But since this
>> > > seems a developer-only thing, that restriction seems fine to me.
>> >
>> > Ummm, I disagree a superuser check is sufficient protection from a
>> > segfault or similar issues.
>>
>> My POV there is that it's the user's responsibility to call the right
>> function; and if they fail to do so, it's their fault.  I agree it's not
>> ideal, but frankly these pageinspect things are not critical to get 100%
>> user-friendly.
>>
>> > If we really want to print something nicer, I'd say it needs to be a
>> > special function in the BRIN opclass.
>>
>> If that can be done, then +1.  We just need to ensure that the function
>> knows and can verify the type of index that the value comes from.  I
>> guess we can pass the index OID so that it can extract the opclass from
>> catalogs to verify.
>
>+1 from me, too. Perhaps we can have it as optional. If a BRIN opclass
>doesn't have it, the 'values' can be null.
>

I'd say that if the opclass does not have it, then we should print the
bytea value (or whatever the opclass uses to store the summary) using
the type functions.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
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