I'm wondering if cx_Oracle works with flask-python.
if so, please share with me a good documentation. it will be great.
Thank you All for your help.
See my blog post How to use Python Flask with Oracle Database which has a runnable example.
The key thing is that during application initialization you will want to start a connection pool with cx_Oracle.SessionPool().
Then each route can get a connection from the pool with connection = pool.acquire()
Also see https://www.oracle.com/webfolder/technetwork/tutorials/obe/cloud/apaas/python/python-oracle-accs/python-oracle-accs.html, however this doesn't use a connection pool so it has some scalability limitations.
Related
I have a python application which interacts with vertica database through vertica python client. Currently there is no connection pool to manage the connections, instead for every request a new connection is opened and then closed at the end of the request. However, this design will cost to handle concurrent requests. Also, the python application is run on a uwsgi and an Nginx server to process multiple requests.
I would like to use an existing connection pool to handle connections to vertica from python but I dont seem to find connection pools like C3Po or Hikari in python. Could you please help me with the pools for python - vertica
For native Postgres, have a look at some of the connection pools discussed at Should PostgreSQL connections be pooled in a Python web app, or create a new connection per request?
For Vertica, it doesn't look like connection pooling is available in the native driver though it might be worth posting an issue on GitHub if you'd like more specific details. You could probably use Vertica's ODBC driver through pyODBC since that supports connedction pooling if configured as discussed at http://www.unixodbc.org/doc/conn_pool.html
I'm connecting my API layer to Oracle DB using the cx_oracle connector, the issue here is that my DB machine keeps on restarting due to some other reasons.
I want to immune my API Layer to reestablish the connection or try to reconnect, what's the best possible solution to this?
Please don't suggest try and catch.
My connection code :
import cx_Oracle
connection_string = "{user}/{password}#{server}:{port}/{sid}".format(
user=config.DB_USER,
password=config.DB_PASSWORD,
server=config.DB_HOST,
port=config.DB_PORT,
sid=config.DB_SID)
db_conn = cx_Oracle.connect(connection_string)
cursor = db_conn.cursor()
I don't know much about this, but would having a session/connection pool help here?
If you use a session pool (cx_Oracle.SessionPool) then dead sessions will be replaced whenever they are requested from the pool. That will not help you with existing sessions that have been acquired from the pool. But if you get an error, and you release the session back to the pool and then acquire a session again from the pool you will get a session that can be used. If you want more advanced protection from database failure you will need to explore some of the more advanced techniques that the Oracle Database has to offer like RAC (Real Application Clusters).
What are methods of having persistent connections to a MongoDB, instead of creating a MongoClient instance and using it when constructing queries? I noted that it opens/closes a connection on each query operation.
I'm using Python, and have pymongo installed. I've looked around and didn't find much information on connection management. In light of this, what are general recommendations on database management?
Just have a global MongoClient at the top level of a Python module:
client = MongoClient(my_connection_string)
It's critical that you create one client at your application's startup. Use that one same client for every operation for the lifetime of your application and never call "close" on it. This will provide optimal performance.
The client manages a connection pool, and reuses connections as much as possible. It does not open and close a new connection per query, that would be awful. See PyMongo's docs for connection pooling.
I've looked through stackoverflow and can see some oldish posts on this and wondered what the current thinking is about pooling connections in Python for MySQL.
We have a set of python processes that are threading with each thread creating a connection to MySQL. This all works fine, but we can have over 150 connections to MySQL.
When I look at the process state in MySQL I can see that most of the connections are asleep most of the time. The application is connecting to a Twitter streaming API so its busy but this only accounts for a few connections.
Is there a good way of adding connection pooling to Python MySQL and can this be done simply without re-writing all of the existing code?
Many thanks.
PT
See DBUtils
Maybe you have an abstract layer for MySQL, you can modify this layer to avoid rewriting all the code.
If not, you have to hack your Python-MySQL driver.
I want to do the following:
Have a software running written in Python 2.7
This software connects to a database (Currently a MySQL database)
This software listen for connections on a port X on TCP
When a connection is established, a client x request or command something, then the software use the database to store, remove or fetch information (Based on the request or command).
What I currently have in head is the classic approach of connecting to the database, store the connection to the database in an object (as a variable) that is passed in the threads that are spawned by the connection listener, then these threads use the variable in the object to do what they need to do with the database connection. (I know that multi-processing is better then multi-threading in Python, but it's not related to my question at this time)
Now my question, how should I use SQLAlchemy in this context? I am quite confused even although I have been reading quite a lot of documentation about it and there doesn't seem to be "good" examples on how to handle this kind of situation specifically even although I have been searching quite a lot.
What is the problem here? SQLAlchemy maintains a thread-local connection pool..what else do you need?