Working with results

Query results are returned as a vulkn.recordset.RecordSet object. RecordSets provide many methods for marshalling the data from a ClickHouse result to a Python friendly format.

show, s

• Description: Provides a pretty print SQL table view of the DataTable result.
• Returns: str
• Example:

  v.table('system.tables').all().head(3).exec().s
  

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show_pandas(num_rows=50)

• Description: Provides a Pandas DataFrame view of the DataTable result.
• Returns: str
• Example:

  >>> v.table('system.tables').all().head(3).exec().show_pandas()
      database                            name  ... sampling_key  storage_policy
  0   system  aggregate_function_combinators  ...          NaN             NaN
  1   system            asynchronous_metrics  ...          NaN             NaN
  2   system                   build_options  ...          NaN             NaN
  
  [3 rows x 16 columns]
  

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len()

• Description: Returns the length of the DataTable result.
• Returns: int
• Example:

  >>> len(v.table('system.tables').all().head(3).exec())
  3
  

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columns

• Description: Returns a list of columns in the DataTable result.
• Returns: list(str)
• Example:

  v.table('system.tables').all().head(3).exec().columns
  ['database', 'name', 'engine', 'is_temporary', 'data_paths', 'metadata_path', 
  'metadata_modification_time', 'dependencies_database', 'dependencies_table', 
  'create_table_query', 'engine_full', 'partition_key', 'sorting_key', 'primary_key', 
  'sampling_key', 'storage_policy']
  

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chtypes

• Description: Returns a list of ClickHouse types for the DataTable result.
• Returns: list(str)
• Example:

  v.table('system.tables').all().head(3).exec().chtypes
  ['String', 'String', 'String', 'UInt8', 'Array(String)', 'String', 'DateTime', 'Array(String)',
  'Array(String)', 'String', 'String', 'String', 'String', 'String', 'String', 'String']
  

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pytypes

• Description: Returns a list of Python types for the DataTable result.
• Returns: list(str)
• Example:

  v.table('system.tables').all().head(3).exec().pytypes
  [<class 'str'>, <class 'str'>, <class 'str'>, <class 'int'>, <class 'object'>, <class 'str'>, 
  <class 'datetime.datetime'>, <class 'object'>, <class 'object'>, <class 'str'>, <class 'str'>, 
  <class 'str'>, <class 'str'>, <class 'str'>, <class 'str'>, <class 'str'>]
  

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pdtypes

• Description: Returns a list of Pandas types for the DataTable result.
• Returns: list(str)
• Example:

  v.table('system.tables').all().head(3).exec().pdtypes
  {'is_temporary': dtype('uint8'), 'metadata_modification_time': dtype('<M8')}
  

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to_records, r

• Description: Returns the result as a list of key/value pair dictionary/records.
• Returns: list(dict)
• Example:

  v.table('system.tables').all().head(3).select('database','name').exec().r
  [{'database': 'system', 'name': 'aggregate_function_combinators'},
   {'database': 'system', 'name': 'asynchronous_metrics'},
   {'database': 'system', 'name': 'build_options'}]
  

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to_pandas, p

• Description: Returns the result as a Pandas DataFrame.
• Returns: Pandas DataFrame
• Example:

  v.table('system.tables').all().head(3).select('database','name').exec().p
    database                            name
  0   system  aggregate_function_combinators
  1   system            asynchronous_metrics
  2   system                   build_options
  

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to_dict, d

• Description: Returns the result as a list of key/value pair dictionary/records.
• Returns: list(dict)
• Example:

  v.table('system.tables').all().head(3).select('database','name').exec().d
  [{'database': 'system', 'name': 'aggregate_function_combinators'},
   {'database': 'system', 'name': 'asynchronous_metrics'},
   {'database': 'system', 'name': 'build_options'}]
  

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to_list, l

• Description: Returns the result as a list of tuples.
• Returns: list(tuple)
• Example:

  v.table('system.tables').all().head(3).select('database','name').exec().l
  [('system', 'aggregate_function_combinators'),
   ('system', 'asynchronous_metrics'),
   ('system', 'build_options')]
  

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to_recarray, n

• Description: Returns the result as a NumPy ndarray.
• Returns: numpy ndarray
• Example:

  v.table('system.tables').all().head(3).select('database','name').exec().n
  rec.array([('system', 'aggregate_function_combinators'),
          ('system', 'asynchronous_metrics'),
          ('system', 'build_options')],
          dtype=[('database', 'O'), ('name', 'O')])
  

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