Readme¶

SQLAlchemy Dialect for EXASOL DB¶

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How to get started¶

Currently, sqlalchemy-exasol supports multiple dialects. The core difference being if the dialect is odbc or websocket based.

Generally, we advise to use the websocket based Dialect, because odbc based dialects require a good understanding of (unix)ODBC and the setup is significant more complicated.

Turbodbc support¶

Warning

Maintenance of this feature is on hold. Also it is very likely that turbodbc support will be dropped in future versions.

You can use Turbodbc with sqlalchemy_exasol if you use a python version >= 3.8.
Multi row update is not supported, see test/test_update.py for an example

Meet the system requirements¶

Python
An Exasol DB (e.g. docker-db or a cloud instance)

ODBC-based dialects additionally require the following to be available and set up:

The packages unixODBC and unixODBC-dev >= 2.2.14
The Exasol ODBC driver
The ODBC.ini and ODBCINST.ini configurations files setup

Setup your python project and install sqlalchemy-exasol¶

$ pip install sqlalchemy-exasol

for turbodbc support:

$ pip install sqlalchemy-exasol[turbodbc]

Talk to the EXASOL DB using SQLAlchemy¶

Websocket based Dialect:

For more details regarding the websocket support checkout the section: “What is Websocket support?”

from sqlalchemy import create_engine
url = "exa+websocket://A_USER:A_PASSWORD@192.168.1.2..8:1234/my_schema?CONNECTIONLCALL=en_US.UTF-8"
e = create_engine(url)
r = e.execute("select 42 from dual").fetchall()

Pyodbc (ODBC based Dialect):

from sqlalchemy import create_engine
url = "exa+pyodbc://A_USER:A_PASSWORD@192.168.1.2..8:1234/my_schema?CONNECTIONLCALL=en_US.UTF-8&driver=EXAODBC"
e = create_engine(url)
r = e.execute("select 42 from dual").fetchall()

Turbodbc (ODBC based Dialect):

from sqlalchemy import create_engine
url = "exa+turbodbc://A_USER:A_PASSWORD@192.168.1.2..8:1234/my_schema?CONNECTIONLCALL=en_US.UTF-8&driver=EXAODBC"
e = create_engine(url)
r = e.execute("select 42 from dual").fetchall()

The dialect supports two types of connection urls creating an engine. A DSN (Data Source Name) mode and a host mode:

Type	Example
DSN URL	‘exa+pyodbc://USER:PWD@exa_test’
HOST URL	‘exa+pyodbc://USER:PWD@192.168.14.227..228:1234/my_schema?parameter’

Features¶

SELECT, INSERT, UPDATE, DELETE statements

Notes¶

Schema name and parameters are optional for the host url
At least on Linux/Unix systems it has proven valuable to pass ‘CONNECTIONLCALL=en_US.UTF-8’ as a url parameter. This will make sure that the client process (Python) and the EXASOL driver (UTF-8 internal) know how to interpret code pages correctly.
Always use all lower-case identifiers for schema, table and column names. SQLAlchemy treats all lower-case identifiers as case-insensitive, the dialect takes care of transforming the identifier into a case-insensitive representation of the specific database (in case of EXASol this is upper-case as for Oracle)
As of Exasol client driver version 4.1.2 you can pass the flag ‘INTTYPESINRESULTSIFPOSSIBLE=y’ in the connection string (or configure it in your DSN). This will convert DECIMAL data types to Integer-like data types. Creating integers is a factor three faster in Python than creating Decimals.