does your dialect override DDLCompiler.get_column_specification()?
That's the best way to get in extra things like NOT NULL, etc. Example:
https://github.com/zzzeek/sqlalchemy/blob/master/lib/sqlalchemy/dialects/mysql/base.py#L982
On 03/01/2017 02:13 PM, Alexander Peletz wrote:
I am using the pyhive library which includes a partial implementation of
the 'hive' dialect. I have edited various aspects of this dialect but I
am still unable to affect the initial create table statement that
Alembic is issuing to build the alembic_version table. Here is what
Alembic is issuing:
'CREATE TABLE `alembic_version` (\n\t`version_num` STRING NOT NULL,
\n\tCONSTRAINT `alembic_version_pkc` PRIMARY KEY (`version_num`)\n)\n\n'
And here is what I need:
'CREATE TABLE `alembic_version` (\n\t`version_num` STRING\n)\n\n'
I have attempted to add a visit_primary_key_constraint() method to my
dialect which simply returns '' but this is having no effect. And I am a
bit lost in finding which method I should override to ensure I never
append a 'NOT NULL' string to the end of a column specification.
Any recommendations?
Thanks,
Alexander
On Friday, February 10, 2017 at 1:26:20 PM UTC-5, mike bayer wrote:
On 02/10/2017 12:41 PM, Alexander Peletz wrote:
> Great thank you for the quick response! I actually found this morning
> that I can put the class definition in alembic/ddl/impl.py and it
works
> (seemed like a logical module for it?).
>
> Next issue is the CREATE TABLE statement used to create the
> alembic_version table uses keywords that are not valid HiveQL
keywords.
> I assume somewhere in the HiveImpl class I could override the
contents
> of this statement, but I couldn't figure out where/how to do that.
for CREATE TABLE assuming you've written a whole SQLAlchemy dialect,
you'll want to look into your DDLCompiler in the visit_create_table
method. This is on the SQLAlchemy side, not Alembic.
However, usually you don't need to override visit_create_table as a
whole, I'd imagine you're needing to deal with something special about
columns, datatypes, or constraints. There are individual methods that
deal with those things, I'd take a look at some of the existing
SQLAlchemy dialects to see how those things get set up.
>
>
> Thanks,
> Alexander
>
> On Friday, February 10, 2017 at 9:45:38 AM UTC-5, mike bayer wrote:
>
>
>
> On 02/10/2017 07:41 AM, Alexander Peletz wrote:
> > Hello,
> >
> > I would like to use Alembic to manage my Hive Metastore. I have
> > installed, PyHive, SqlAlchemy, and Alembic. I am able to
create a
> > functional engine object using the 'hive' dialect in
sqlalchemy,
> however
> > I cannot get Alembic to recognize this dialect. The problem
> appears to
> > be a lack of a HiveImpl class in the Alembic package. I
attempted to
> > resolve this by creating an alembic/ddl/hive.py module and
pasting
> the
> > following code into that module:
> >
> >
> > from .impl import DefaultImpl
> >
> > class HiveImpl(DefaultImpl):
> > __dialect__ = 'hive'
>
>
>
> you don't actually have to create a "hive.py" file. Anywhere
in your
> hive dialect, simply put the above code that you have (using the
> correct
> imports of course). The DefaultImpl uses a metaclass that
will allow
> the "hive" name to be available to alembic as a result of this
class
> being created.
>
>
> >
> >
> >
> >
> > I simply want to be able to execute raw SQL against a Hive
> instance (no
> > ORM implementation needed) and I was hoping to use Alembic to
> manage the
> > minimum upgrade/downgrade functionality. Are there any
simple edits I
> > can make to the Alembic source code to allow me to achieve
this goal?
> >
> >
> >
> > Thanks,
> >
> > Alexander
> >
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