SQL Backend Base Classes¶
BaseSQLBackend (BaseBackend)
¶
Base backend class for backends that compile to SQL.
Attributes¶
current_database: str | None
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: str
inherited
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)
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, expr, limit=None, params=None, timecontext=None)
¶
Compille an Ibis expression.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
expr |
ir.Expr |
Ibis expression |
required |
limit |
str | None |
For expressions yielding result sets; retrieve at most this number of values/rows. Overrides any limit already set on the expression. |
None |
params |
Mapping[ir.Expr, Any] | None |
Named unbound parameters |
None |
timecontext |
TimeContext | None |
Additional information about data source time boundaries |
None |
Returns:
Type | Description |
---|---|
Any |
The output of compilation. The type of this value depends on the backend. |
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 |
create_table(self, name, obj=None, schema=None, database=None)
inherited
¶
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,
|
None |
schema |
ibis.Schema | None |
The schema for the new table. Only one of |
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)
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 |
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)
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 |
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 |
execute(self, expr, params=None, limit='default', **kwargs)
¶
Compile and execute an Ibis expression.
Compile and execute Ibis expression using this backend client interface, returning results in-memory in the appropriate object type
Parameters:
Name | Type | Description | Default |
---|---|---|---|
expr |
ir.Expr |
Ibis expression |
required |
limit |
str |
For expressions yielding result sets; retrieve at most this number of values/rows. Overrides any limit already set on the expression. |
'default' |
params |
Mapping[ir.ScalarExpr, Any] | None |
Named unbound parameters |
None |
kwargs |
Any |
Backend specific arguments. For example, the clickhouse backend
uses this to receive |
{} |
Returns:
Type | Description |
---|---|
DataFrame | Series | Scalar |
|
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 |
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 |
explain(self, expr, params=None)
¶
Explain an expression.
Return the query plan associated with the indicated expression or SQL query.
Returns:
Type | Description |
---|---|
str |
Query plan |
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)
inherited
¶
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 |
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 | 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 |
raw_sql(self, query, results=False)
¶
Execute a query string.
Could have unexpected results if the query modifies the behavior of the session in a way unknown to Ibis; be careful.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
query |
str |
DML or DDL statement |
required |
Returns:
Type | Description |
---|---|
Any |
Backend cursor |
sql(self, query)
¶
Convert a SQL query to an Ibis table expression.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
query |
str |
SQL string |
required |
Returns:
Type | Description |
---|---|
ir.TableExpr |
Table expression |
table(self, name, database=None)
¶
Construct a table expression.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
name |
str |
Table name |
required |
database |
str | None |
Database name |
None |
Returns:
Type | Description |
---|---|
ir.TableExpr |
Table expression |
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