Re: WIP: Rework access method interface

On Thu, Nov 12, 2015 at 2:49 PM, Alexander Korotkov <
a(dot)korotkov(at)postgrespro(dot)ru> wrote:

> On Tue, Nov 3, 2015 at 3:16 PM, Alexander Korotkov <
> a(dot)korotkov(at)postgrespro(dot)ru> wrote:
>
>> On Tue, Nov 3, 2015 at 2:36 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>
>>> Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
>>> > Tom Lane wrote:
>>> >> I'm kind of inclined to just let the verifiers read the catalogs for
>>> >> themselves. AFAICS, a loop around the results of SearchSysCacheList
>>> >> is not going to be significantly more code than what this patch does,
>>> >> and it avoids presuming that we know what the verifiers will wish to
>>> >> look at.
>>>
>>> > Hmm, so this amounts to saying the verifier can only run after the
>>> > catalog rows are written. Is that okay?
>>>
>>> Why not? Surely we are not interested in performance-optimizing for
>>> the case of a detectably incorrect CREATE OP CLASS command.
>>>
>>> I don't actually care that much about running the verifiers during
>>> CREATE/etc OP CLASS at all. It's at least as important to be able
>>> to run them across the built-in opclasses, considering all the chances
>>> for human error in constructing those things. Even in the ALTER OP CLASS
>>> case, the verifier would likely need to look at existing catalog rows as
>>> well as the new ones. So basically, I see zero value in exposing CREATE/
>>> ALTER OP CLASS's internal working representation to the verifiers.
>>>
>>
>> I'm OK with validating opclass directly by system catalog, i.e. looping
>> over SearchSysCacheList results. Teodor was telling me something similar
>> personally.
>> I'll also try to rearrange header according to the comments upthread.
>>
>
> The next revision of patch is attached.
> The changes are following:
>
> 1. Definitions of Selectivity, Cost and declarations
> of IndexAmRoutine, PlannerInfo, IndexPath, IndexInfo are moved into
> separate header reldecls.h. That allows to get rid of #include
> "nodes/relation.h" in amapi.h.
> 2. amvalidate method now gets opclass oid as parameter. Internally,
> amvalidate implementations do catalog lookups. opfam_internal.h isn't
> included from inappropriate places anymore.
> 3. I removed amvalidate calls from opclasscmds.c. Validating
> user-defined opclasses is behavior change which can have issues with
> backward compatibility. I think if we want to introduce this, it should be
> considered separately of API rework.
>
> ​Patch was rebased against current master.
Any notes about current version of patch?
It would be nice to commit it and continue work on other parts of am
extendability.​

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company