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Backend Base Classes

BaseBackend (ABC)

Base backend class.

All Ibis backends must subclass this class and implement all the required methods.

Attributes

current_database: str | None 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: str 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

Methods

add_operation(self, operation)

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, expr, params=None)

Compile an expression.

connect(self, *args, **kwargs)

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)

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, name, obj=None, schema=None, database=None)

Create a new table.

Not all backends implement this method.

Parameters:

Name Type Description Default
name str

Name of the new table.

required
obj pd.DataFrame | ir.TableExpr | None

An Ibis table expression or pandas table that will be used to extract the schema and the data of the new table. If not provided, schema must be given.

None
schema ibis.Schema | None

The schema for the new table. Only one of schema or obj can be provided.

None
database str | None

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

None

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

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)

Return a Database object for the name database.

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

Parameters:

Name Type Description Default
name str | 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)

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)

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, expr)

Execute an expression.

exists_database(self, name)

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)

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

has_operation(operation) classmethod

Return whether the backend implements support for operation.

Parameters:

Name Type Description Default
operation type[ops.ValueOp]

A class corresponding to an operation.

required

Examples:

>>> import ibis
>>> import ibis.expr.operations as ops
>>> ibis.sqlite.has_operation(ops.ArrayIndex)
False
>>> ibis.postgres.has_operation(ops.ArrayIndex)
True

Returns:

Type Description
bool

Whether the backend implements the operation.

list_databases(self, like=None)

List existing databases in the current connection.

Parameters:

Name Type Description Default
like str

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)

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 | None

A pattern in Python's regex format.

None
database str | None

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.

register_options() classmethod

Register custom backend options.

table(self, name, database=None)

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)

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