SQLAlchemy 2.0 data type support for Oracle backend

[jkmacc-LANL]

Error thrown when trying to create a table in Oracle database using the following function (NNSA KB Core Affiliation table used as an example):

import pisces.schema.kbcore as kb

engine = sqlalchemy.create_engine(connection_string)

class Affiliation(kb.Affiliation):
    __tablename__ = 'test_affiliation'

    @classmethod
    def mk_table(cls, engine):
        """Creates SQL table stored in 'cls' in database"""
        cls.__base__.metadata.create_all(engine)

Affiliation.mk_table(engine)

Trying to create the table in the database throws the following error:

sqlalchemy.exc.ArgumentError: Oracle FLOAT types use 'binary precision', which does not convert cleanly from decimal 'precision'.  Please specify this type with a separate Oracle variant, such as Float(precision=53).with_variant(oracle.FLOAT(binary_precision=176), 'oracle'), so that the Oracle specific 'binary_precision' may be specified accurately.

Error can be resolved by manually formatting data types during column assignments, like (using time column as example):

/home/bspears/repo/pisces/pisces/kbcore.py

--> 507    time = Column(Float(precision=53).with_variant(oracle.FLOAT(binary_precision=53), 'oracle'),
    508        info={'default': -9999999999.999, 'parse': parse_float, 'dtype': 'float', 'width': 17, 'format': '17.5f'})

ping: @bspears-LANL @rad-lanl