PostgreSQL

https://www.postgresql.org

Install

Install Ibis and dependencies for the Postgres backend:

Install with the postgres extra:

pip install 'ibis-framework[postgres]'

And connect:

import ibis

con = ibis.postgres.connect()
1
Adjust connection parameters as needed.

Install for Postgres:

conda install -c conda-forge ibis-postgres

And connect:

import ibis

con = ibis.postgres.connect()
1
Adjust connection parameters as needed.

Install for Postgres:

mamba install -c conda-forge ibis-postgres

And connect:

import ibis

con = ibis.postgres.connect()
1
Adjust connection parameters as needed.

Connect

ibis.postgres.connect

con = ibis.postgres.connect(
    user="username",
    password="password",
    host="hostname",
    port=5432,
    database="database",
)
Note

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

Connection Parameters

do_connect

do_connect(self, host=None, user=None, password=None, port=5432, database=None, schema=None, url=None, driver='psycopg2')

Create an Ibis client connected to PostgreSQL database.

Parameters
Name Type Description Default
host str | None Hostname None
user str | None Username None
password str | None Password None
port int Port number 5432
database str | None Database to connect to None
schema str | None PostgreSQL schema to use. If None, use the default search_path. None
url str | None SQLAlchemy connection string. If passed, the other connection arguments are ignored. None
driver typing.Literal[‘psycopg2’] Database driver 'psycopg2'
Examples
>>> import os
>>> import getpass
>>> import ibis
>>> host = os.environ.get("IBIS_TEST_POSTGRES_HOST", "localhost")
>>> user = os.environ.get("IBIS_TEST_POSTGRES_USER", getpass.getuser())
>>> password = os.environ.get("IBIS_TEST_POSTGRES_PASSWORD")
>>> database = os.environ.get("IBIS_TEST_POSTGRES_DATABASE", "ibis_testing")
>>> con = connect(database=database, host=host, user=user, password=password)
>>> con.list_tables()
[...]
>>> t = con.table("functional_alltypes")
>>> t
PostgreSQLTable[table]
  name: functional_alltypes
  schema:
    id : int32
    bool_col : boolean
    tinyint_col : int16
    smallint_col : int16
    int_col : int32
    bigint_col : int64
    float_col : float32
    double_col : float64
    date_string_col : string
    string_col : string
    timestamp_col : timestamp
    year : int32
    month : int32

ibis.connect URL format

In addition to ibis.postgres.connect, you can also connect to Postgres by passing a properly-formatted Postgres connection URL to ibis.connect:

con = ibis.connect(f"postgres://{user}:{password}@{host}:{port}/{database}")

postgres.Backend

add_operation

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.

begin

begin(self)

compile

compile(self, expr, limit=None, params=None, timecontext=None)

Compile an Ibis expression.

Parameters

Name Type Description Default
expr ibis.ibis.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 collections.abc.Mapping[ibis.ibis.Expr, typing.Any] | None Named unbound parameters None
timecontext tuple[pandas.pandas.Timestamp, pandas.pandas.Timestamp] | None Additional information about data source time boundaries None

Returns

Type Description
typing.Any The output of compilation. The type of this value depends on the backend.

connect

connect(self, *args, **kwargs)

Connect to the database.

Parameters

Name Type Description Default
*args Mandatory connection parameters, see the docstring of do_connect for details. ()
**kwargs Extra connection parameters, see the docstring of do_connect for details. {}

Notes

This creates a new backend instance with saved args and kwargs, then calls reconnect and finally returns the newly created and connected backend instance.

Returns

Type Description
ibis.backends.base.BaseBackend An instance of the backend

create_schema

create_schema(self, name, database=None, force=False)

Create a schema named name in database.

Parameters

Name Type Description Default
name str Name of the schema to create. required
database str | None Name of the database in which to create the schema. If None, the current database is used. None
force bool If False, an exception is raised if the schema exists. False

create_table

create_table(self, name, obj=None, *, schema=None, database=None, temp=False, overwrite=False)

Create a table.

Parameters

Name Type Description Default
name str Name of the new table. required
obj pandas.pandas.DataFrame | pyarrow.pyarrow.Table | ibis.ibis.Table | 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.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
temp bool Should the table be temporary for the session. False
overwrite bool Clobber existing data False

Returns

Type Description
Table The table that was created.

create_view

create_view(self, name, obj, *, database=None, overwrite=False)

database

database(self, name=None)

Return a Database object for the name database.

Parameters

Name Type Description Default
name str | None Name of the database to return the object for. None

Returns

Type Description
ibis.backends.base.Database A database object for the specified database.

drop_schema

drop_schema(self, name, database=None, force=False)

Drop the schema with name in database.

Parameters

Name Type Description Default
name str Name of the schema to drop. required
database str | None Name of the database to drop the schema from. If None, the current database is used. None
force bool If False, an exception is raised if the schema does not exist. False

drop_table

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

Drop a table.

Parameters

Name Type Description Default
name str Table to drop required
database str | None Database to drop table from None
force bool Check for existence before dropping False

drop_view

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

execute

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 ibis.ibis.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 collections.abc.Mapping[ibis.ibis.Scalar, typing.Any] | None Named unbound parameters None
kwargs typing.Any Backend specific arguments. For example, the clickhouse backend uses this to receive external_tables as a dictionary of pandas DataFrames. {}

Returns

Type Description
DataFrame | Series | Scalar * Table: pandas.DataFrame * Column: pandas.Series * Scalar: Python scalar value

fetch_from_cursor

fetch_from_cursor(self, cursor, schema)

function

function(self, name, *, schema=None)

has_operation

has_operation(cls, operation)

insert

insert(self, table_name, obj, database=None, overwrite=False)

Insert data into a table.

Parameters

Name Type Description Default
table_name str The name of the table to which data needs will be inserted required
obj pandas.pandas.DataFrame | ibis.ibis.Table | list | dict The source data or expression to insert required
database str | None Name of the attached database that the table is located in. None
overwrite bool If True then replace existing contents of table False

Raises

Type Description
NotImplementedError If inserting data from a different database
ValueError If the type of obj isn’t supported

list_databases

list_databases(self, like=None)

list_schemas

list_schemas(self, like=None, database=None)

list_tables

list_tables(self, like=None, schema=None)

List the tables in the database.

Parameters

Name Type Description Default
like A pattern to use for listing tables. None
schema The schema to perform the list against. ::: {.callout-warning} ## schema refers to database hierarchy The schema parameter does not refer to the column names and types of table. ::: None

raw_sql

raw_sql(self, query)

Execute a query and return the cursor used for execution.

Consider using .sql instead

If your query is a SELECT statement you can use the backend .sql method to avoid having to manually release the cursor returned from this method.

The cursor returned from this method must be manually released

You do not need to call .close() on the cursor when running DDL or DML statements like CREATE, INSERT or DROP, only when using SELECT statements.

To release a cursor, call the close method on the returned cursor object.

You can close the cursor by explicitly calling its close method:

cursor = con.raw_sql("SELECT ...")
cursor.close()

Or you can use a context manager:

with con.raw_sql("SELECT ...") as cursor:
    ...

Parameters

Name Type Description Default
query str | sqlalchemy.sqlalchemy.sql.sqlalchemy.sql.ClauseElement SQL query or SQLAlchemy expression to execute required

Examples

>>> con = ibis.connect("duckdb://")
>>> with con.raw_sql("SELECT 1") as cursor:
...     result = cursor.fetchall()
>>> result
[(1,)]
>>> cursor.closed
True

read_csv

read_csv(self, path, table_name=None, **kwargs)

Register a CSV file as a table in the current backend.

Parameters

Name Type Description Default
path str | pathlib.Path The data source. A string or Path to the CSV file. required
table_name str | None An optional name to use for the created table. This defaults to a sequentially generated name. None
**kwargs typing.Any Additional keyword arguments passed to the backend loading function. {}

Returns

Type Description
ibis.ibis.Table The just-registered table

read_delta

read_delta(self, source, table_name=None, **kwargs)

Register a Delta Lake table in the current database.

Parameters

Name Type Description Default
source str | pathlib.Path The data source. Must be a directory containing a Delta Lake table. required
table_name str | None An optional name to use for the created table. This defaults to a sequentially generated name. None
**kwargs typing.Any Additional keyword arguments passed to the underlying backend or library. {}

Returns

Type Description
ibis.ibis.Table The just-registered table.

read_json

read_json(self, path, table_name=None, **kwargs)

Register a JSON file as a table in the current backend.

Parameters

Name Type Description Default
path str | pathlib.Path The data source. A string or Path to the JSON file. required
table_name str | None An optional name to use for the created table. This defaults to a sequentially generated name. None
**kwargs typing.Any Additional keyword arguments passed to the backend loading function. {}

Returns

Type Description
ibis.ibis.Table The just-registered table

read_parquet

read_parquet(self, path, table_name=None, **kwargs)

Register a parquet file as a table in the current backend.

Parameters

Name Type Description Default
path str | pathlib.Path The data source. required
table_name str | None An optional name to use for the created table. This defaults to a sequentially generated name. None
**kwargs typing.Any Additional keyword arguments passed to the backend loading function. {}

Returns

Type Description
ibis.ibis.Table The just-registered table

reconnect

reconnect(self)

Reconnect to the database already configured with connect.

register_options

register_options(cls)

Register custom backend options.

rename_table

rename_table(self, old_name, new_name)

Rename an existing table.

Parameters

Name Type Description Default
old_name str The old name of the table. required
new_name str The new name of the table. required

schema

schema(self, name)

Get an ibis schema from the current database for the table name.

Parameters

Name Type Description Default
name str Table name required

Returns

Type Description
Schema The ibis schema of name

sql

sql(self, query, schema=None, dialect=None)

Convert a SQL query to an Ibis table expression.

Parameters

Name Type Description Default
query str SQL string required
schema ibis.ibis.Schema | None The expected schema for this query. If not provided, will be inferred automatically if possible. None
dialect str | None Optional string indicating the dialect of query. The default value of None will use the backend’s native dialect. None

Returns

Type Description
Table Table expression

table

table(self, name, database=None, schema=None)

Create a table expression from a table in the database.

Parameters

Name Type Description Default
name str Table name required
database str | None The database the table resides in None
schema str | None The schema inside database where the table resides. ::: {.callout-warning} ## schema refers to database hierarchy The schema parameter does not refer to the column names and types of table. ::: None

Returns

Type Description
Table Table expression

to_csv

to_csv(self, expr, path, *, params=None, **kwargs)

Write the results of executing the given expression to a CSV file.

This method is eager and will execute the associated expression immediately.

Parameters

Name Type Description Default
expr ibis.ibis.Table The ibis expression to execute and persist to CSV. required
path str | pathlib.Path The data source. A string or Path to the CSV file. required
params collections.abc.Mapping[ibis.ibis.Scalar, typing.Any] | None Mapping of scalar parameter expressions to value. None
kwargs typing.Any Additional keyword arguments passed to pyarrow.csv.CSVWriter {}
https required

to_delta

to_delta(self, expr, path, *, params=None, **kwargs)

Write the results of executing the given expression to a Delta Lake table.

This method is eager and will execute the associated expression immediately.

Parameters

Name Type Description Default
expr ibis.ibis.Table The ibis expression to execute and persist to Delta Lake table. required
path str | pathlib.Path The data source. A string or Path to the Delta Lake table. required
params collections.abc.Mapping[ibis.ibis.Scalar, typing.Any] | None Mapping of scalar parameter expressions to value. None
kwargs typing.Any Additional keyword arguments passed to deltalake.writer.write_deltalake method {}

to_pandas

to_pandas(self, expr, *, params=None, limit=None, **kwargs)

Execute an Ibis expression and return a pandas DataFrame, Series, or scalar.

Note

This method is a wrapper around execute.

Parameters

Name Type Description Default
expr ibis.ibis.Expr Ibis expression to execute. required
params collections.abc.Mapping[ibis.ibis.Scalar, typing.Any] | None Mapping of scalar parameter expressions to value. None
limit int | str | None An integer to effect a specific row limit. A value of None means “no limit”. The default is in ibis/config.py. None
kwargs typing.Any Keyword arguments {}

to_pandas_batches

to_pandas_batches(self, expr, *, params=None, limit=None, chunk_size=1000000, **kwargs)

Execute an Ibis expression and return an iterator of pandas DataFrames.

Parameters

Name Type Description Default
expr ibis.ibis.Expr Ibis expression to execute. required
params collections.abc.Mapping[ibis.ibis.Scalar, typing.Any] | None Mapping of scalar parameter expressions to value. None
limit int | str | None An integer to effect a specific row limit. A value of None means “no limit”. The default is in ibis/config.py. None
chunk_size int Maximum number of rows in each returned DataFrame batch. This may have no effect depending on the backend. 1000000
kwargs typing.Any Keyword arguments {}

Returns

Type Description
collections.abc.Iterator[pandas.pandas.DataFrame] An iterator of pandas DataFrames.

to_parquet

to_parquet(self, expr, path, *, params=None, **kwargs)

Write the results of executing the given expression to a parquet file.

This method is eager and will execute the associated expression immediately.

Parameters

Name Type Description Default
expr ibis.ibis.Table The ibis expression to execute and persist to parquet. required
path str | pathlib.Path The data source. A string or Path to the parquet file. required
params collections.abc.Mapping[ibis.ibis.Scalar, typing.Any] | None Mapping of scalar parameter expressions to value. None
**kwargs typing.Any Additional keyword arguments passed to pyarrow.parquet.ParquetWriter {}
https required

to_pyarrow

to_pyarrow(self, expr, *, params=None, limit=None, **kwargs)

Execute expression and return results in as a pyarrow table.

This method is eager and will execute the associated expression immediately.

Parameters

Name Type Description Default
expr ibis.ibis.Expr Ibis expression to export to pyarrow required
params collections.abc.Mapping[ibis.ibis.Scalar, typing.Any] | None Mapping of scalar parameter expressions to value. None
limit int | str | None An integer to effect a specific row limit. A value of None means “no limit”. The default is in ibis/config.py. None
kwargs typing.Any Keyword arguments {}

Returns

Type Description
Table A pyarrow table holding the results of the executed expression.

to_pyarrow_batches

to_pyarrow_batches(self, expr, *, params=None, limit=None, chunk_size=1000000, **_)

Execute expression and return an iterator of pyarrow record batches.

This method is eager and will execute the associated expression immediately.

Parameters

Name Type Description Default
expr ibis.ibis.Expr Ibis expression to export to pyarrow required
limit int | str | None An integer to effect a specific row limit. A value of None means “no limit”. The default is in ibis/config.py. None
params collections.abc.Mapping[ibis.ibis.Scalar, typing.Any] | None Mapping of scalar parameter expressions to value. None
chunk_size int Maximum number of rows in each returned record batch. 1000000

Returns

Type Description
RecordBatchReader Collection of pyarrow RecordBatchs.

to_torch

to_torch(self, expr, *, params=None, limit=None, **kwargs)

Execute an expression and return results as a dictionary of torch tensors.

Parameters

Name Type Description Default
expr ibis.ibis.Expr Ibis expression to execute. required
params collections.abc.Mapping[ibis.ibis.Scalar, typing.Any] | None Parameters to substitute into the expression. None
limit int | str | None An integer to effect a specific row limit. A value of None means no limit. None
kwargs typing.Any Keyword arguments passed into the backend’s to_torch implementation. {}

Returns

Type Description
dict[str, torch.torch.Tensor] A dictionary of torch tensors, keyed by column name.

truncate_table

truncate_table(self, name, database=None)

Back to top