kedro.extras.datasets.pandas.SQLTableDataSet¶
- class kedro.extras.datasets.pandas.SQLTableDataSet(table_name, credentials, load_args=None, save_args=None)[source]¶
SQLTableDataSet
loads data from a SQL table and saves a pandas dataframe to a table. It usespandas.DataFrame
internally, so it supports all allowed pandas options onread_sql_table
andto_sql
methods. Since Pandas uses SQLAlchemy behind the scenes, when instantiatingSQLTableDataSet
one needs to pass a compatible connection string either incredentials
(see the example code snippet below) or inload_args
andsave_args
. Connection string formats supported by SQLAlchemy can be found here: https://docs.sqlalchemy.org/en/13/core/engines.html#database-urlsSQLTableDataSet
modifies the save parameters and stores the data with no index. This is designed to make load and save methods symmetric.Example usage for the YAML API:
shuttles_table_dataset: type: pandas.SQLTableDataSet credentials: db_credentials table_name: shuttles load_args: schema: dwschema save_args: schema: dwschema if_exists: replace
Sample database credentials entry in
credentials.yml
:db_credentials: con: postgresql://scott:tiger@localhost/test
Example usage for the Python API:
from kedro.extras.datasets.pandas 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
Methods
create_connection
(connection_str)Given a connection string, create singleton connection to be used across all instances of SQLTableDataSet that need to connect to the same source.
exists
()Checks whether a data set's output already exists by calling the provided _exists() method.
from_config
(name, config[, load_version, ...])Create a data set instance using the configuration provided.
load
()Loads data by delegation to the provided load method.
release
()Release any cached data.
save
(data)Saves data by delegation to the provided save method.
- DEFAULT_LOAD_ARGS: Dict[str, Any] = {}¶
- DEFAULT_SAVE_ARGS: Dict[str, Any] = {'index': False}¶
- __init__(table_name, credentials, load_args=None, save_args=None)[source]¶
Creates a new
SQLTableDataSet
.- Parameters
table_name (
str
) – The table name to load or save data to. It overwrites name insave_args
andtable_name
parameters inload_args
.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-urlsload_args (
Optional
[Dict
[str
,Any
]]) – Provided to underlying pandasread_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-urlssave_args (
Optional
[Dict
[str
,Any
]]) – Provided to underlying pandasto_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 hasindex=False
in the default parameters.
- Raises
DatasetError – When either
table_name
orcon
is empty.
- classmethod create_connection(connection_str)[source]¶
Given a connection string, create singleton connection to be used across all instances of SQLTableDataSet that need to connect to the same source.
- Return type
None
- engines: Dict[str, Any] = {}¶
- 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 – Data set name.
config – Data set config dictionary.
load_version – 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 – 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.
- Returns
An instance of an
AbstractDataset
subclass.- Raises
DatasetError – When the function fails to create the data set from its config.
- load()¶
Loads data by delegation to the provided load method.
- Return type
TypeVar
(_DO
)- 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 release method raises error.
- Return type
None
- save(data)¶
Saves data by delegation to the provided save method.
- Parameters
data (
TypeVar
(_DI
)) – the value to be saved by provided save method.- Raises
DatasetError – when underlying save method raises error.
FileNotFoundError – when save method got file instead of dir, on Windows.
NotADirectoryError – when save method got file instead of dir, on Unix.
- Return type
None