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I'm using a python script with the python library MySQLdb to upload a large amount of data to a local MySQL database. When I used a sample of the data everything ran fine and uploaded. Now I am using all of my data (it's about 300000 lines split into 12000 text files) and I receive the following error:

"OperationalError: (2003, ""Can't connect to MySQL server on 'localhost' (10055)"")"    

At the point where it crashes it has uploaded 17231 rows of information. I'm using Python 2.7, Win7 64 and MySQL 5.1.53 on a desktop machine. I used a WAMP installation and view the data using PhpMyAdmin. An example of the function I am using to upload the data is as follows:

# upload data
def updateDB(db, table, values):

    db = MySQLdb.connect (host = 'localhost', user = 'root', passwd = '', db = db)
    cursor = db.cursor()
    print str(values)
    cursor.execute(makeSQLHeader(table, values), values)     

This works fine for the test data, and the text file structure is identical for all of my data. What would be a good strategy to address this problem?

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I'm inclined to think this is timeout issue. How long does your real test take approximately? – DTest Jul 29 '11 at 17:06
Found this, not sure how valid it is since I haven't worked with python… – DTest Jul 29 '11 at 17:07
Not very long, about a fraction of a second. – celenius Jul 29 '11 at 17:08
Are you opening a connection per file (and are they running in parallel)? – DTest Jul 29 '11 at 17:13
although I'm assuming the loop is serial, I think you might be better off only opening one connection for the duration. – DTest Jul 29 '11 at 17:24
up vote 4 down vote accepted

My two thoughts on this are that either it's taking a long time to load and you're disconnecting with a timeout. There are some ways to autoreconnect in python found here Here are the relevant timeout variables in mysql: wait_timeout and interactive_timeout

Second idea, and from discussion in comments it looks like the right one. You're probably hitting the mysql connection limit by opening a connection per file.

Try opening a single connection and running the test (when you do this, you might hit the timeout, depending on how long it takes).

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Thanks - that fixed it. – celenius Jul 29 '11 at 18:47

It could be that you run into the limits of maximum allowed packets. You could set something like this in my.cnf:


For more information see this article in the MySQL reference guide.

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