Readme¶

SQLAlchemy Dialect for EXASOL DB¶

How to get started¶

We assume you have a good understanding of (unix)ODBC. If not, make sure you read their documentation carefully - there are lot’s of traps 🪤 to step into.

Meet the system requirements¶

On Linux/Unix like systems you need:

Python
An Exasol DB (e.g. docker-db or a cloud instance)
The packages unixODBC and unixODBC-dev >= 2.2.14
The Exasol ODBC driver
The ODBC.ini and ODBCINST.ini configurations files setup

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

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¶

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()

to use turbodbc as driver:

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
you can even use the MERGE statement (see unit tests for examples)

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.