Hi, I know this is a long time, but did you ever get SQLAlchemy to
successfully work with Vertica ?
Please let me know as I am interested in doing the same.
Thanks,
Femi Anthony
On Tuesday, February 2, 2010 11:37:15 AM UTC-5, Bo wrote:
Hi Michael,
Thanks for the tip on dialect creation; I have a working connection
and much of the low level library functionality appears to just
work.
I've just started digging into the internals to begin implementing
introspection support. One issue I've encountered is that PyODBC
happens to return boolean columns as strings with values 1 and 0.
This confuses the current type system. I have skimmed the
TypeDecorator documentation but am still confused about how to
associate that with this custom dialect. Any hints?
I have attached the dialect base.py and a few test cases (not sure
they're useful as Vertica is frustratingly secretive about everything)
if you have time to review and comment.
On Fri, Jan 15, 2010 at 2:57 PM, Bo Shi bs1...@gmail.com javascript:
wrote:
That's funny because Oracle and SQL server are utterly, totally
different
from a SQL quirks perspective. If I were to pick two dialects in SQLA
that were *most* different from each other and also non-standard, those
would be the two.
I was a bit puzzled by this also (granted this was from some early
press release I dredged up* from google). I'm still working through
their documentation and haven't run across any configuration that
might enable a compatability mode yet.
* improved compatibility with Oracle and SQLServer SQL dialects
http://www.vertica.com/company/news_and_events/Vertica-Analytics-Database-2.5-The-Most-Cost-Effective-Way-To-Modernize-Data-Warehousing
create_engine()
using 'mssql+pyodbc' seems to work but upon attempting to execute a
simple select statement, I get a programming error indicating the
following failed to run:
'SELECT user_name() as user_name;'
So it seems the dialect is getting some additional state under the
hood. lib/sqlalchemy/dialects/mssql/pyodbc.py appears to be hooking
PyODBCConnector and MSDialect together. Is it possible to specify
another dialect here? If so, is there any documentation on how to do
so?
you'd want to make yourself a vertica dialect module that imports the
PyODBCConnector and uses it as a mixin. I'd suggest copying one of the
existing dialects, and probably not the SQL server one unless you know
that vertica has a lot of the transact-SQL lineage that SQL server does
(the PG and SQLite dialects are the most barebones).To run it, add a
setup.py which configures your library as a setuptools entry point, in
this case the name would be vertica+pyodbc:
from setuptools import setup
setup(name=SQLAVertica,
description=...,
entry_points={
'sqlalchemy:plugins':
['vertica+pyodbc = mypackage.base:VerticaDialect']
}
then using create_engine('vertica+pyodbc://user:pw@host/dbname') will
load
in your dialect.
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