kedro.io.SQLTableDataSet

class kedro.io.SQLTableDataSet(table_name, credentials, load_args=None, save_args=None)

Bases: kedro.io.core.AbstractDataSet

SQLTableDataSet loads data from a SQL table and saves a pandas dataframe to a table. It uses pandas.DataFrame internally, so it supports all allowed pandas options on read_sql_table and to_sql methods. Since Pandas uses SQLAlchemy behind the scenes, when instantiating SQLTableDataSet one needs to pass a compatible connection string either in credentials (see the example code snippet below) or in load_args and save_args. Connection string formats supported by SQLAlchemy can be found here: https://docs.sqlalchemy.org/en/13/core/engines.html#database-urls

SQLTableDataSet modifies the save parameters and stores the data with no index. This is designed to make load and save methods symmetric.

Example:

from kedro.io import SQLTableDataSet
import pandas as pd

data = pd.DataFrame({"col1": [1, 2], "col2": [4, 5],
                     "col3": [5, 6]})
table_name = "table_a"
credentials = {
    "con": "postgresql://scott:tiger@localhost/test"
}
data_set = SQLTableDataSet(table_name=table_name,
                           credentials=credentials)

data_set.save(data)
reloaded = data_set.load()

assert data.equals(reloaded)

Attributes

SQLTableDataSet.DEFAULT_LOAD_ARGS
SQLTableDataSet.DEFAULT_SAVE_ARGS

Methods

SQLTableDataSet.__init__(table_name, credentials)	Creates a new SQLTableDataSet.
SQLTableDataSet.exists()	Checks whether a data set’s output already exists by calling the provided _exists() method.
SQLTableDataSet.from_config(name, config[, …])	Create a data set instance using the configuration provided.
SQLTableDataSet.get_last_load_version()	Versioned datasets should override this property to return last loaded version
SQLTableDataSet.get_last_save_version()	Versioned datasets should override this property to return last saved version.
SQLTableDataSet.load()	Loads data by delegation to the provided load method.
SQLTableDataSet.release()	Release any cached data.
SQLTableDataSet.save(data)	Saves data by delegation to the provided save method.

DEFAULT_LOAD_ARGS = {}

DEFAULT_SAVE_ARGS = {'index': False}

__init__(table_name, credentials, load_args=None, save_args=None)

Creates a new SQLTableDataSet.

Parameters:

• table_name (str) – The table name to load or save data to. It overwrites name in save_args and table_name parameters in load_args.
• credentials (Dict[str, Any]) – A dictionary with a SQLAlchemy connection string. Users are supposed to provide the connection string ‘con’ through credentials. It overwrites con parameter in load_args and save_args in case it is provided. To find all supported connection string formats, see here: https://docs.sqlalchemy.org/en/13/core/engines.html#database-urls
• load_args (Optional[Dict[str, Any]]) – Provided to underlying pandas read_sql_table function along with the connection string. To find all supported arguments, see here: https://pandas.pydata.org/pandas-docs/stable/generated/pandas.read_sql_table.html To find all supported connection string formats, see here: https://docs.sqlalchemy.org/en/13/core/engines.html#database-urls
• save_args (Optional[Dict[str, Any]]) – Provided to underlying pandas to_sql function along with the connection string. To find all supported arguments, see here: https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.to_sql.html To find all supported connection string formats, see here: https://docs.sqlalchemy.org/en/13/core/engines.html#database-urls It has index=False in the default parameters.

Raises:

DataSetError – When either table_name or con is empty.

Return type:

None

exists()

Checks whether a data set’s output already exists by calling the provided _exists() method.

Return type:bool Returns:Flag indicating whether the output already exists. Raises:DataSetError – when underlying exists method raises error.

classmethod from_config(name, config, load_version=None, save_version=None)

Create a data set instance using the configuration provided.

Parameters:

• name (str) – Data set name.
• config (Dict[str, Any]) – Data set config dictionary.
• load_version (Optional[str]) – Version string to be used for load operation if the data set is versioned. Has no effect on the data set if versioning was not enabled.
• save_version (Optional[str]) – Version string to be used for save operation if the data set is versioned. Has no effect on the data set if versioning was not enabled.

Return type:

AbstractDataSet

Returns:

An instance of an AbstractDataSet subclass.

Raises:

DataSetError – When the function fails to create the data set from its config.

get_last_load_version()

Versioned datasets should override this property to return last loaded version

Return type:Optional[str]

get_last_save_version()

Versioned datasets should override this property to return last saved version.

Return type:Optional[str]

load()

Loads data by delegation to the provided load method.

Return type:Any Returns:Data returned by the provided load method. Raises:DataSetError – When underlying load method raises error.

release()

Release any cached data.

Raises:DataSetError – when underlying exists method raises error. Return type:None

save(data)

Saves data by delegation to the provided save method.

Parameters:data (Any) – the value to be saved by provided save method. Raises:DataSetError – when underlying save method raises error. Return type:None