⚡️ v2.5.0 Add `Pipe.indices`, improve memory usage for MSSQL.

[bmeares]

v2.5.0

• Add indices to Pipe.parameters.
  You may now explicitly state the indices to be created by defining indices (or indexes) in Pipe.parameters (or the Pipe constructor for your convenience).

  import meerschaum as mrsm
  
  pipe = mrsm.Pipe(
    'software', 'versions',
    instance='sql:local',
    columns=['major', 'minor', 'patch'],
    indices={
        'all': ['major', 'minor', 'patch'],
    },
  )
  mrsm.pprint(pipe.get_indices())
  # {
  #     'major': 'IX_software_versions_major',
  #     'minor': 'IX_software_versions_minor',
  #     'patch': 'IX_software_versions_patch',
  #     'all': 'IX_software_versions_major_minor_patch'
  # } 

  You may also use the key index_template to change the format of the generated index names (defaults to IX_{target}_{column_names}, where target is the table name and column_names consists of all of the index's columns joined by an underscore).

  pipe.parameters['index_template'] = "foo_{target}_{column_names}"
  mrsm.pprint(pipe.get_indices())
  # {'all': 'foo_software_versions_major_minor_patch'} 

• Enable chunking for MSSQL
  To improve memory usage, chunksize is now accepted by SQLConnector.read() for the flavor mssql.

• Disable pyodbc pooling.
  To properly recycle the connection pool in the SQLAlchemy engine, the internal pyodbc pooling must be disabled. See the SQLAlchemy documentation.

• Bugfixes
  Other miscellaneous bugfixes have been included in this release, such as resolving broken imports during certain edge cases