Re: proposal - assign result of query to psql variable

Hi Pavel,

(2012/09/21 2:01), Pavel Stehule wrote:
>> - Is it intentional that \gset can set special variables such as
>> AUTOCOMMIT and HOST?  I don't see any downside for this behavior,
>> because \set also can do that, but it is not documented nor tested at all.
>>
>
> I use a same "SetVariable" function, so a behave should be same

It seems reasonable.

>> Document
>> ========
>> - Adding some description of \gset command, especially about limitation
>> of variable list, seems necessary.
>> - In addition to the meta-command section, "Advanced features" section
>> mentions how to set psql's variables, so we would need some mention
>> there too.
>> - The term "target list" might not be familiar to users, since it
>> appears in only sections mentioning PG internal relatively.  I think
>> that the feature described in the section "Retrieving Query Results" in
>> ECPG document is similar to this feature.
>> http://www.postgresql.org/docs/devel/static/ecpg-variables.html
>
> I invite any proposals about enhancing documentation. Personally I am
> a PostgreSQL developer, so I don't known any different term other than
> "target list" - but any user friendly description is welcome.

How about to say "stores the query's result output into variable"?
Please see attached file for my proposal.  I also mentioned about 1-row
limit and omit of variable.

>> Coding
>> ======
>> The code follows our coding conventions.  Here are comments for coding.
>>
>> - Some typo found in comments, please see attached patch.
>> - There is a code path which doesn't print error message even if libpq
>> reported error (PGRES_BAD_RESPONSE, PGRES_NONFATAL_ERROR,
>> PGRES_FATAL_ERROR) in StoreQueryResult.  Is this intentional?  FYI, ecpg
>> prints "bad response" message for those errors.
>
> yes - it is question. I use same pattern like PrintQueryResult, but
> "bad response" message should be used.
>
> I am sending updated patch

It seems ok.

BTW, as far as I see, no psql backslash command including \setenv (it
was added in 9.2) has regression test in core (I mean src/test/regress).
 Is there any convention about this issue?  If psql backslash commands
(or any psql feature else) don't need regression test, we can remove
psql.(sql|out).
# Of course we need to test new feature by hand.

Anyway, IMO the name psql impresses larger area than the patch
implements.  How about to rename psql to psql_cmd or backslash_cmd than
psql as regression test name?

--
Shigeru HANADA