This is my python code and I want to connect my Amazon Redshift database to Python, but it is showing error in host.
Can anyone tell me the correct syntax? Am I passing all the parameters correctly?
con=psycopg2.connect("dbname = pg_table_def, host=redshifttest-icp.cooqucvshoum.us-west-2.redshift.amazonaws.com, port= 5439, user=me, password= secret")
This is the error:
OperationalError: could not translate host name "redshift://redshifttest-xyz.cooqucvshoum.us-west-2.redshift.amazonaws.com," to address: Unknown host
It appears that you wish to run Amazon Redshift queries from Python code.
The parameters you would want to use are:
Database name
field when the cluster was created. Master user name
field when the cluster was created. Master user password
field when the cluster was created. redshifttest-xyz.cooqucvshoum.us-west-2.redshift.amazonaws.com
5439
For example:
con=psycopg2.connect("dbname=sales host=redshifttest-xyz.cooqucvshoum.us-west-2.redshift.amazonaws.com port=5439 user=master password=secret")
Old question but I just arrived here from Google.
The accepted answer doesn't work with SQLAlchemy, although it's powered by psycopg2:
sqlalchemy.exc.ArgumentError: Could not parse rfc1738 URL from string 'dbname=... host=... port=... user=... password=...'
What worked:
create_engine(f"postgresql://{REDSHIFT_USER}:{REDSHIFT_PASSWORD}@{REDSHIFT_HOST}:{REDSHIFT_PORT}/{REDSHIFT_DATABASE}")
Which works with psycopg2 directly too:
psycopg2.connect(f"postgresql://{REDSHIFT_USER}:{REDSHIFT_PASSWORD}@{REDSHIFT_HOST}:{REDSHIFT_PORT}/{REDSHIFT_DATABASE}")
Using the postgresql
dialect works because Amazon Redshift is based on PostgreSQL .
Hope it can help other people
To connect to redshift, you need the postgres+psycopg2 Install it as For Python 3.x:
pip3 install psycopg2-binary
And then use
return create_engine(
"postgresql+psycopg2://%s:%s@%s:%s/%s"
% (REDSHIFT_USERNAME, urlquote(REDSHIFT_PASSWORD), REDSHIFT_HOST, RED_SHIFT_PORT,
REDSHIFT_DB,)
)
The easiest way to query AWS Redshift from python is through this Jupyter extension - Jupyter Redshift
Not only can you query and save your results but also write them back to the database from within the notebook environment.
Well, for Redshift the idea is made COPY from S3, is faster than every different way, but here is some example to do it:
first you must install some dependencies
for linux users sudo apt-get install libpq-dev
for mac users brew install libpq
install with pip this dependencies pip3 install psycopg2-binary
pip3 install sqlalchemy
pip3 install sqlalchemy-redshift
import sqlalchemy as sa
from sqlalchemy.orm import sessionmaker
#>>>>>>>> MAKE CHANGES HERE <<<<<<<<<<<<<
DATABASE = "dwtest"
USER = "youruser"
PASSWORD = "yourpassword"
HOST = "dwtest.awsexample.com"
PORT = "5439"
SCHEMA = "public"
S3_FULL_PATH = 's3://yourbucket/category_pipe.txt'
ARN_CREDENTIALS = 'arn:aws:iam::YOURARN:YOURROLE'
REGION = 'us-east-1'
############ CONNECTING AND CREATING SESSIONS ############
connection_string = "redshift+psycopg2://%s:%s@%s:%s/%s" % (USER,PASSWORD,HOST,str(PORT),DATABASE)
engine = sa.create_engine(connection_string)
session = sessionmaker()
session.configure(bind=engine)
s = session()
SetPath = "SET search_path TO %s" % SCHEMA
s.execute(SetPath)
###########################################################
############ RUNNING COPY ############
copy_command = '''
copy category from '%s'
credentials 'aws_iam_role=%s'
delimiter '|' region '%s';
''' % (S3_FULL_PATH, ARN_CREDENTIALS, REGION)
s.execute(copy_command)
s.commit()
######################################
############ GETTING DATA ############
query = "SELECT * FROM category;"
rr = s.execute(query)
all_results = rr.fetchall()
def pretty(all_results):
for row in all_results :
print("row start >>>>>>>>>>>>>>>>>>>>")
for r in row :
print(" ---- %s" % r)
print("row end >>>>>>>>>>>>>>>>>>>>>>")
pretty(all_results)
s.close()
######################################
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