pyro/run.py at development · Greyvend/pyro · GitHub

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import logging
from operator import itemgetter

from sqlalchemy import create_engine
from sqlalchemy.engine.url import URL

from pyro import db, tj, transformation, representation, cfg
from pyro.utils import relation_name, assemble_list, attribute_name


if __name__ == '__main__':
    # load configuration
    cfg.load('config-2.json')

    # setup logging
    logging.basicConfig(**cfg.settings['logging'])

    # connect to source Database
    logging.info('Connecting to the source DB: {}'.format(
        cfg.settings['source_db']['database']))
    source_engine = create_engine(str(URL(**cfg.settings['source_db'])))

    relations, dependencies = db.get_schema(source_engine)

    # get multi valued dependencies from the config
    mvd = cfg.settings.get('multi valued dependencies', [])
    # transform lists of attributes to sets of attributes
    mvd = [{part: set(attributes) for part, attributes in dep.items()}
           for dep in mvd]
    dependencies.extend(mvd)

    # get main attributes
    dimension_attributes = [list(map(attribute_name, d['attributes']))
                            for d in cfg.settings['dimensions']]
    measure_relation = relation_name(cfg.settings['measure'])
    measure_attribute = attribute_name(cfg.settings['measure'])

    # Start transformation
    # build contexts
    logging.info('Building dimension contexts...')
    contexts = []
    base_total = {measure_relation}
    # build dimension contexts
    for dimension in cfg.settings['dimensions']:
        logging.info('Building context for dimension "{}"'.format(
            dimension['name']))
        # extract relation names from extended attribute names in config
        base = set(map(relation_name, dimension['attributes']))
        base_total |= base
        # for now pick first found context
        context = next(transformation.contexts(relations, base, dependencies))
        contexts.append(context)

    # build application context
    if cfg.settings['app_context']:
        logging.info('Building application context')
        try:
            app_context = next(transformation.contexts(relations, base_total,
                                                       dependencies))
        except StopIteration:
            # no combination satisfies Lossless Join property. Pick all
            # relations
            logging.warning('No lossless combinations were found, picking '
                            'whole relation set for application application '
                            'context')
            app_context = relations
    else:
        logging.info('Combining all the contexts to form application context')
        app_context = assemble_list(contexts, key=lambda r: r['name'])
    contexts.append(app_context)

    # get logical constraints
    constraints = list(map(lambda d: d.get('constraint', []),
                           cfg.settings['dimensions']))
    constraints.append([])  # no application constraint will be used

    cache_file_path = cfg.settings.get('cache_file', 'cache.json')

    # connect to the output DB
    logging.info('Connecting to the cube DB: {}'.format(
        cfg.settings['cube_db']['database']))
    cube_engine = create_engine(URL(**cfg.settings['cube_db']))

    table_names = []
    for context, constraint, dimension in zip(contexts, constraints,
                                              dimension_attributes + [[]]):
        logging.info('Building Table of Joins for the context {}'.format(
            list(map(itemgetter('name'), context))))
        table_of_joins = tj.build(context, dependencies, constraint,
                                  source_engine, cube_engine, cache_file_path)
        table_names.append(table_of_joins['name'])

    logging.info('The source Database has been successfully transformed to '
                 'OLAP representation!')

    logging.info('Writing the result table to the file')
    representation.create(cube_engine, table_names, dimension_attributes,
                          measure_attribute, cfg.settings['output_file'])