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¶
str | None Name of the current database.
db_identity: str
cached
property
writable
¶
Return the identity of the database.
Multiple connections to the same
database will return the same value for db_identity.
The default implementation assumes connection parameters uniquely specify the database.
Returns¶
Hashable Database identity
tables
cached
property
writable
¶
An accessor for tables in the database.
Tables may be accessed by name using either index or attribute access:
Examples¶
con = ibis.sqlite.connect("example.db") people = con.tables['people'] # access via index people = con.tables.people # access via attribute
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¶
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)
¶
create_database(self, name, force=False)
¶
Create a new database.
Not all backends implement this method.
Parameters¶
name
Name of the new database.
force
If False, an exception is raised if the database already exists.
create_table(self, name, obj=None, schema=None, database=None)
¶
Create a new table.
Not all backends implement this method.
Parameters¶
name
Name of the new table.
obj
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.
schema
The schema for the new table. Only one of schema or obj can be
provided.
database
Name of the database where the table will be created, if not the
default.
create_view(self, name, expr, database=None)
¶
Create a view.
Parameters¶
name Name for the new view. expr An Ibis table expression that will be used to extract the query of the view. database Name of the database where the view will be created, if not the default.
database(self, name=None)
¶
drop_table(self, name, database=None, force=False)
¶
Drop a table.
Parameters¶
name
Name of the table to drop.
database
Name of the database where the table exists, if not the default.
force
If False, an exception is raised if the table does not exist.
drop_view(self, name, database=None, force=False)
¶
Drop a view.
Parameters¶
name
Name of the view to drop.
database
Name of the database where the view exists, if not the default.
force
If False, an exception is raised if the view does not exist.
execute(self, expr)
¶
Execute an expression.
exists_database(self, name)
¶
exists_table(self, name, database=None)
¶
has_operation(operation)
classmethod
¶
Return whether the backend implements support for operation.
Parameters¶
operation A class corresponding to an operation.
Returns¶
bool Whether the backend implements the operation.
Examples¶
import ibis import ibis.expr.operations as ops ibis.sqlite.has_operation(ops.ArrayIndex) False ibis.postgres.has_operation(ops.ArrayIndex) True
list_databases(self, like=None)
¶
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¶
like : str, optional A pattern in Python's regex format. database : str, optional The database to list tables of, if not the current one.
Returns¶
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