0.5.x changes the connection method to accept kwargs instead of a dict to be more dbapi compliant. copy methods improved and consolidated in 0.5.1
0.4.x breaks some of the older query interfaces (row_handler callback, and connection.query). It replaces the row_handler callback with an iterate() method. Please see examples below If you are on 0.4.x, please upgrade to 0.4.6 as there are various bug fixes
vertica-python is a native Python adapter for the Vertica (http://www.vertica.com) database.
vertica-python is currently in beta stage; it has been tested for functionality and has a very basic test suite. Please use with caution, and feel free to submit issues and/or pull requests (after running the unit tests).
vertica-python has been tested with Vertica 6.1.2/7.0.0+ and Python 2.6/2.7.
If you're using pip >= 1.4 and you don't already have pytz installed:
pip install --pre pytz
To install vertica-python with pip:
pip install vertica-python
To install vertica-python with pip (with optional namedparams dependencies):
# see 'Using named parameters' section below
pip install 'vertica-python[namedparams]'
Source code for vertica-python can be found at:
http://github.com/uber/vertica-python
# install nose if you don't have it
pip install -r requirements_test.txt
# you will need to have access to a vertica database.
# connection info is in tests/basic_tests.py
# run tests
nosetests
Create connection
from vertica_python import connect
conn_info = {'host': '127.0.0.1',
'port': 5433,
'user': 'some_user',
'password': 'some_password',
'database': 'a_database'}
# simple connection, with manual close
connection = vertica_python.connect(**conn_info)
# do things
connection.close()
# using with for auto connection closing after usage
with vertica_python.connect(**conn_info) as connection:
# do thingsStream query results:
cur = connection.cursor()
cur.execute("SELECT * FROM a_table LIMIT 2")
for row in cur.iterate():
print(row)
# [ 1, 'some text', datetime.datetime(2014, 5, 18, 6, 47, 1, 928014) ]
# [ 2, 'something else', None ]Streaming is recommended if you want to further process each row, save the results in a non-list/dict format (e.g. Pandas DataFrame), or save the results in a file.
In-memory results as list:
cur = connection.cursor()
cur.execute("SELECT * FROM a_table LIMIT 2")
cur.fetchall()
# [ [1, 'something'], [2, 'something_else'] ]In-memory results as dictionary:
cur = connection.cursor('dict')
cur.execute("SELECT * FROM a_table LIMIT 2")
cur.fetchall()
# [ {'id': 1, 'value': 'something'}, {'id': 2, 'value': 'something_else'} ]
connection.close()Query using named parameters:
# Using named parameter bindings requires psycopg2>=2.5.1 which is not includes with the base vertica_python requirements.
cur = connection.cursor()
cur.execute("SELECT * FROM a_table WHERE a = :propA b = :propB", {'propA': 1, 'propB': 'stringValue'})
cur.fetchall()
# [ [1, 'something'], [2, 'something_else'] ]Insert and commits :
cur = connection.cursor()
# inline commit
cur.execute("INSERT INTO a_table (a, b) VALUES (1, 'aa'); commit;")
# commit in execution
cur.execute("INSERT INTO a_table (a, b) VALUES (1, 'aa')")
cur.execute("INSERT INTO a_table (a, b) VALUES (2, 'bb')")
cur.execute("commit;")
# connection.commit()
cur.execute("INSERT INTO a_table (a, b) VALUES (1, 'aa')")
connection.commit()Copy :
cur = connection.cursor()
cur.copy("COPY test_copy (id, name) from stdin DELIMITER ',' ", csv)Where csv is either a string or a file-like object (specifically, any object with a read() method). If using a file, the data is streamed.
vertica_python behaves a bit differently then dbapi when returning rowcounts
After a select execution, the rowcount will be -1, indicating that the row count is unknown. The rowcount value will be updated as data is streamed.
cur.execute('SELECT 10 things')
cur.rowcount == -1 # indicates unknown rowcount
cur.fetchone()
cur.rowcount == 1
cur.fetchone()
cur.rowcount == 2
cur.fetchall()
cur.rowcount == 10After an insert/update/delete, the rowcount will be returned as a single element row:
cur.execute("DELETE 3 things")
cur.rowcount == -1 # indicates unknown rowcount
cur.fetchone()[0] == 3If you execute multiple statements in a single call to execute(), you can use cursor.nextset() to retrieve all of the data.
cur.execute('SELECT 1; SELECT 2;')
cur.fetchone()
# [1]
cur.fetchone()
# None
cur.nextset()
# True
cur.fetchone()
# [2]
cur.fetchone()
# None
cur.nextset()
# NoneMIT License, please see LICENSE for details.
Many thanks go to the contributors to the Ruby Vertica gem (https://github.com/sprsquish/vertica), since they did all of the wrestling with Vertica's protocol and have kept the gem updated. They are: