Re: PATCH: psql tab completion for SELECT

On 03/04/2018 08:06 PM, Tom Lane wrote:
> Edmund Horner <ejrh00@gmail.com> writes:
>> On 26 January 2018 at 13:44, Vik Fearing <vik.fearing@2ndquadrant.com> wrote:
>>> On 01/26/2018 01:28 AM, Edmund Horner wrote:
>>>> The patch mentioned attempts to put savepoints around the tab
>>>> completion query where appropriate.
> 
>>> I am -1 on this idea.
> 
>> May I ask why?  It doesn't stop psql working against older versions,
>> as it checks that the server supports savepoints.
> 
> I looked into this patch and was disappointed to discover that it had
> only a very ad-hoc solution to the problem of version-dependent tab
> completion queries.  We need something better --- in particular, the
> recent prokind changes mean that there needs to be a way to make
> SchemaQuery queries version-dependent.
> 
> So ... here is a modest proposal.  It invents a VersionedQuery concept
> and also extends the SchemaQuery infrastructure to allow those to be
> versioned.  I have not taken this nearly as far as it could be taken,
> since it's mostly just proposing mechanism.  To illustrate the
> VersionedQuery infrastructure, I fixed it so it wouldn't send
> publication/subscription queries to pre-v10 servers, and to illustrate
> the versioned SchemaQuery infrastructure, I fixed the prokind problems.
> 
> If people like this approach, I propose to commit this more or less
> as-is.  The select-tab-completion patch would then need to be rewritten
> to use this infrastructure, but I think that should be straightforward.
> As a separate line of work, the infrastructure could be applied to fix
> the pre-existing places where tab completion fails against old servers.
> But that's probably work for v12 or beyond, unless somebody's really
> motivated to do it right now.

Tab completion on functions in SELECT (a subset of this thread's patch)
is quite important to me personally.  I will work on this in the coming
days.
-- 
Vik Fearing                                          +33 6 46 75 15 36
http://2ndQuadrant.fr     PostgreSQL : Expertise, Formation et Support