Hi Niclas,
2017-10-26 9:15 GMT+03:00 Niclas Hedhman <[email protected]>:
>
> Is it reasonable to ask that JOOQ *createTableIfNotExists()* knows which
> underlying SQL implementations that supports it natively and does a "SELECT
> 1 FROM ..." automatically for those that don't ??
>
Sure, this is very desirable. And the feature is actually emulated in those
databases that do not support it, *if* they support anonymous procedural
blocks. E.g. in Oracle, the emulation runs something along the lines of:
begin
execute immediate '
create table "t"(
"i" number null,
"n" decimal(3, 1) null,
"s" varchar2(5) not null
)
';
exception
when others then
if sqlerrm like 'ORA-00955%' then null;
else raise;
end if;
end;
There might just be dialects where we either didn't do it yet, or where we
didn't figure out how it could be done. What dialect(s) are you interested
in, and do you have a pointer on how it could be done?
We could certainly also run two queries from the client instead of just
one. The problem with that is (so far) that we have to update our execution
model and all the SPIs like ExecuteListener to take into account the
possibility of a single execute() call by the client running several
queries. Also, what will Query.getSQL() produce? A ";" separated statement
batch? This will take some time to design properly.
A much better solution would be to emulate anonymous blocks where they're
not available by creating temporary stored procedures. This would be
feature request https://github.com/jOOQ/jOOQ/issues/6474.
There are other similar issues, such as knowing which SQL types are
> supported, if schemas are supported and probably a lot more I have not come
> across yet. Perhaps a first step is to have a
>
>
>
>
> * public class SQL { : :*
>
> * public static boolean supports( SQLDialect dialect, Feature
> feature ) { ... }*
>
>
> * : : }*
>
>
> *if( DSL.supports( dialect, Features.createTableIfNotExists() ) {}*
>
Yeah, that suggestion has been discussed before. I'm not really a big fan
of it. From 10 years of experience developing jOOQ, I don't feel like
there's a thing like a well-defined "feature".
Note, however, that we already annotate the entire API with the
@org.jooq.Support annotation. Since jOOQ 3.9, you can type check your API
usage using the checker framework plugin that we've added. A detailed blog
post about this can be found here:
https://blog.jooq.org/2016/05/09/jsr-308-and-the-checker-framework-add-even-more-typesafety-to-jooq-3-9
If that sounds like something you'd like to use, I'd really appreciate any
feedback you could provide. We haven't seen much feedback on this
interesting feature yet.
>
> *if( DSL.supports( dialect, Features.dataType(
> Types.TIMESTAMP_WITH_TIMEZONE) )*
>
Good point, we should annotate SQLDataType with the @Support annotation as
well. I've created a feature request for this:
https://github.com/jOOQ/jOOQ/issues/6741
Let me know if you see any additional missing features, I'll be very happy
to discuss them.
Thanks,
Lukas
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