kedro.extras.datasets.pandas.SQLQueryDataSet¶
-
class
kedro.extras.datasets.pandas.
SQLQueryDataSet
(sql, credentials, load_args=None)[source]¶ Bases:
kedro.io.core.AbstractDataSet
SQLQueryDataSet
loads data from a provided SQL query. It usespandas.DataFrame
internally, so it supports all allowed pandas options onread_sql_query
. Since Pandas uses SQLAlchemy behind the scenes, when instantiatingSQLQueryDataSet
one needs to pass a compatible connection string either incredentials
(see the example code snippet below) or inload_args
. Connection string formats supported by SQLAlchemy can be found here: https://docs.sqlalchemy.org/en/13/core/engines.html#database-urlsIt does not support save method so it is a read only data set. To save data to a SQL server use
SQLTableDataSet
.Example:
from kedro.extras.datasets.pandas import SQLQueryDataSet import pandas as pd data = pd.DataFrame({"col1": [1, 2], "col2": [4, 5], "col3": [5, 6]}) sql = "SELECT * FROM table_a" credentials = { "con": "postgresql://scott:tiger@localhost/test" } data_set = SQLQueryDataSet(sql=sql, credentials=credentials) sql_data = data_set.load()
Methods
SQLQueryDataSet.__init__
(sql, credentials[, …])Creates a new SQLQueryDataSet
.SQLQueryDataSet.exists
()Checks whether a data set’s output already exists by calling the provided _exists() method. SQLQueryDataSet.from_config
(name, config[, …])Create a data set instance using the configuration provided. SQLQueryDataSet.load
()Loads data by delegation to the provided load method. SQLQueryDataSet.release
()Release any cached data. SQLQueryDataSet.save
(data)Saves data by delegation to the provided save method. -
__init__
(sql, credentials, load_args=None)[source]¶ Creates a new
SQLQueryDataSet
.Parameters: - sql (
str
) – The sql query statement. - credentials (
Dict
[str
,Any
]) – A dictionary with aSQLAlchemy
connection string. Users are supposed to provide the connection string ‘con’ through credentials. It overwrites con parameter inload_args
andsave_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 pandasread_sql_query
function along with the connection string. To find all supported arguments, see here: https://pandas.pydata.org/pandas-docs/stable/generated/pandas.read_sql_query.html To find all supported connection string formats, see here: https://docs.sqlalchemy.org/en/13/core/engines.html#database-urls
Raises: DataSetError
– When eithersql
orcon
parameters is emtpy.Return type: None
- sql (
-
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.
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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 forload
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 forsave
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.- name (
-
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.
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release
()¶ Release any cached data.
Raises: DataSetError
– when underlying release method raises error.Return type: None
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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
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