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Dask

Experimental

The Dask backend is experimental and is subject to backwards incompatible changes.

Install

Install ibis and dependencies for the Dask backend:

pip install 'ibis-framework[dask]'
conda install -c conda-forge ibis-dask
mamba install -c conda-forge ibis-dask

Connect

API

Create a client by passing in a dictionary of paths to ibis.dask.connect.

See ibis.backends.dask.Backend.do_connect for connection parameter information.

ibis.dask.connect is a thin wrapper around ibis.backends.dask.Backend.do_connect.

Connection Parameters

do_connect(self, dictionary)

Construct a Dask backend client from a dictionary of data sources.

Parameters:

Name Type Description Default
dictionary MutableMapping[str, dd.DataFrame]

Mapping from str table names to Dask DataFrames.

required

Examples:

>>> import ibis
>>> data = {"t": "path/to/file.parquet", "s": "path/to/file.csv"}
>>> ibis.dask.connect(data)

Backend API

Backend (BasePandasBackend)

Attributes

current_database inherited property readonly

Return the name of the current database.

Backends that don't support different databases will return None.

Returns:

Type Description
str | None

Name of the current database.

version property readonly

Return the version of the backend engine.

For database servers, return the server version.

For others such as SQLite and pandas return the version of the underlying library or application.

Returns:

Type Description
str

The backend version

Classes

Options (BaseModel) inherited pydantic-model
Attributes
enable_trace: bool pydantic-field

Enable tracing for execution.

Methods

add_operation(self, operation) inherited

Add a translation function to the backend for a specific operation.

Operations are defined in ibis.expr.operations, and a translation function receives the translator object and an expression as parameters, and returns a value depending on the backend. For example, in SQL backends, a NullLiteral operation could be translated to the string "NULL".

Examples:

>>> @ibis.sqlite.add_operation(ibis.expr.operations.NullLiteral)
... def _null_literal(translator, expression):
...     return 'NULL'
compile(self, query, params=None, **kwargs)

Compile expr.

connect(self, *args, **kwargs) inherited

Connect to the database.

Parameters:

Name Type Description Default
args None

Connection parameters

()
kwargs None

Additional connection parameters

{}

Returns:

Type Description
BaseBackend

An instance of the backend

create_database(self, name, force=False) inherited

Create a new database.

Not all backends implement this method.

Parameters:

Name Type Description Default
name str

Name of the new database.

required
force bool

If False, an exception is raised if the database already exists.

False
create_table(self, table_name, obj=None, schema=None)

Create a table.

create_view(self, name, expr, database=None) inherited

Create a view.

Parameters:

Name Type Description Default
name str

Name for the new view.

required
expr ir.TableExpr

An Ibis table expression that will be used to extract the query of the view.

required
database str | None

Name of the database where the view will be created, if not the default.

None
database(self, name=None) inherited

Return a Database object for the name database.

DEPRECATED: database is deprecated; use equivalent methods in the backend

Parameters:

Name Type Description Default
name None

Name of the database to return the object for.

None

Returns:

Type Description
Database

A database object for the specified database.

drop_table(self, name, database=None, force=False) inherited

Drop a table.

Parameters:

Name Type Description Default
name str

Name of the table to drop.

required
database str | None

Name of the database where the table exists, if not the default.

None
force bool

If False, an exception is raised if the table does not exist.

False
drop_view(self, name, database=None, force=False) inherited

Drop a view.

Parameters:

Name Type Description Default
name str

Name of the view to drop.

required
database str | None

Name of the database where the view exists, if not the default.

None
force bool

If False, an exception is raised if the view does not exist.

False
execute(self, query, params=None, limit='default', **kwargs)

Execute an expression.

exists_database(self, name) inherited

Return whether a database name exists in the current connection.

DEPRECATED: exists_database is deprecated as of v2.0; use name in client.list_databases()

Parameters:

Name Type Description Default
name str

Database to check for existence

required

Returns:

Type Description
bool

Whether name exists

exists_table(self, name, database=None) inherited

Return whether a table name exists in the database.

DEPRECATED: exists_table is deprecated as of v2.0; use name in client.list_tables()

Parameters:

Name Type Description Default
name str

Table name

required
database str | None

Database to check if given

None

Returns:

Type Description
bool

Whether name is a table

from_dataframe(self, df, name='df', client=None) inherited

Construct an ibis table from a pandas DataFrame.

Parameters:

Name Type Description Default
df pd.DataFrame

A pandas DataFrame

required
name str

The name of the pandas DataFrame

'df'
client BasePandasBackend | None

Client dictionary will be mutated with the name of the DataFrame, if not provided a new client is created

None

Returns:

Type Description
ir.TableExpr

A table expression

list_databases(self, like=None) inherited

List existing databases in the current connection.

Parameters:

Name Type Description Default
like None

A pattern in Python's regex format to filter returned database names.

None

Returns:

Type Description
list[str]

The database names that exist in the current connection, that match the like pattern if provided.

list_tables(self, like=None, database=None) inherited

Return the list of table names in the current database.

For some backends, the tables may be files in a directory, or other equivalent entities in a SQL database.

Parameters:

Name Type Description Default
like str

A pattern in Python's regex format.

None
database str

The database to list tables of, if not the current one.

None

Returns:

Type Description
list[str]

The list of the table names that match the pattern like.

table(self, name, schema=None) inherited

Return a table expression from the database.

DEPRECATED: table is deprecated as of v2.0; change the current database before calling .table()

verify(self, expr, params=None) inherited

Verify expr is an expression that can be compiled.

DEPRECATED: verify is deprecated as of v2.0; compile and capture TranslationError instead


Last update: March 1, 2022