Con4445 jesus

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Copyright © 2013, Oracle and/or its affiliates. All rights reserved.

Developing with
MySQL Connector/Python
Dr. Paulo Jesus
Software Developer

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Program Agenda
 Introduction of Connector/Python
 Download and Installation
 Coding
 About Performance
 Frameworks and Applications

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Introduction

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Introducing MySQL Connector/Python

 MySQL Database Driver
 Pure Python, no 3rd party dependencies

 Python v2 and v3
 For MySQL, by MySQL
 Documentation
– http://dev.mysql.com/doc/connector-python/en/index.html

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Pure Python

 Written entirely using Python
 No compiling against MySQL client libraries

 Only Standard Library used
 Developed for Python v2 and v3
 PEP-249 compliant

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Current Connector/Python Versions

 v1.0
– GA since September 2012

– v1.0.12 released August 2013

 v1.1
– Alpha since June 2013

– Some new features:
 Prepared Statements and Pooling
 Django backend included

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Python Support
Overview of supported Python version
2.4

2.5

2.6

2.7

3.0

3.1

3.2

3.3

v1.0

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?

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



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v1.1







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

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Connector/Python

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MySQL Server Support

 MySQL v5.5 and higher
 Known to work on earlier versions
– No old password hashing support
– MySQL v4.0 and older will not work

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Download & Installation

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Dependencies
Python!
 For Windows
– Install Python from http://python.org

 Other systems
– should have Python (2.6 or greater)

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Download

 MySQL Website
– http://dev.mysql.com/downloads/connector/python

 Available as
– TAR/ZIP archive
– RPM and Debian package

– Windows Installer (MSI)

 Launchpad
– https://launchpad.net/myconnpy

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Download

 Example file names:
– mysql-connector-python-1.1.1.zip

– mysql-connector-python-1.1.1-py2.7.msi
– mysql-connector-python-1.1.1.el6.noarch.rpm

 Architecture independent

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Installation: Using TAR/ZIP
Running setup.py
 Most common way
 Works anywhere
– .. where Python is installed

 For both Python v2 & v3

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Installation: Universal
Using setup.py
shell> unzip mysql-connector-1.0.12.zip
shell> cd mysql-connector-1.0.12
shell> python setup.py install
# Or any other Python binary
shell> /opt/python/3.3/bin/python3 setup.py install

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Installation using RPM and Debian package

# On Oracle Linux
shell> rpm -i mysql-connector-python-1.1.1.el6.noarch.rpm
# On Ubuntu
shell> dpkg -i
mysql-connector-python_1.0.12-1ubuntu12.04_all.deb

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Installation: using PyPI
Python Package Index
shell> easy_install mysql-connector-python

or
shell> pip install mysql-connector-python

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Install Inside Virtual Environment
Useful for testing and new development
# If not installed yet
shell> pip install virtualenv
shell> virtualenv ENV
shell> source ENV/bin/activate
shell> pip install mysql-connector-python

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Coding

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Classes and Objects
mysql.connector module
 import mysql.connector
 mysql.connector.connect()
– accepts numerous arguments
– returns a MySQLConnection

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Classes and Objects
MySQLConnection
 MySQLConnection
– connects with MySQL

– retrieve server information
– reconfigure and reconnect
– commit/rollback transactions

– create MySQLCursor objects

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Classes and Objects
MySQLCursor
 MySQLCursor
– fetch & manipulate data

– transactions
– different flavors (buffered, raw)

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Connecting with MySQL
Basic connection
import mysql.connector
cnx = mysql.connector.connect(user='root',
host='prod.example.com')
print(cnx.connection_id)
cnx.close()

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Connecting with MySQL
Use a dict to hold configuration & use IPv6
CONFIG = {
'user': 'root',
'host': '::1',
}
cnx = mysql.connector.connect(**CONFIG)
print(cnx.connection_id)
cnx.close()
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Reconnecting with MySQL
Reconfigure and reconnect
cnx = mysql.connector.connect(**CONFIG)

cnx.config(user='joe', password='mysecret')
cnx.reconnect()
cnx.close()

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Cursor methods
MySQLCursor class
 execute(query, data)
– data is list of values

 fetchone()
– returns row as tuple

 fetchmany(20)
– Get the next 20 rows (or less) as list of tuples

 fetchall()
– Get all, or remaining, as list of tuples

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Fetching Data
Fetch a row
cur = cnx.cursor()
cur.execute("SELECT NOW()")
result= cur.fetchone()[0]
print(result)
cur.close()
# Result
(datetime.datetime(2013, 9, 2, 10, 41, 58))
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Fetching Data
Going through results using iterator
query = (
"SELECT id, last_name FROM employees "
"WHERE id > %s AND first_name LIKE %s"
)
cur.execute(query, (500, 'J%'))
for row in cur:
print("{id} {name}".format(id=row[0], name=row[1]))
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Manipulating data
Inserting, updating and deleting
insert_stmt = (
"INSERT INTO employees (first_name, last_name) "
"VALUES (%s, %s)
)
cur = cnx.cursor()
cur.execute(insert_stmt, ('John', 'Doe'))
print("ID of new employee: {id}".format(id=cur.lastrowid))
cnx.commit()
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Change Many Records
MySQLCursor.executemany()
data = [
('John', 'Doe'),
('Jane', 'Doe'),
]
cur.executemany(insert_stmt, data)
cnx.commit()

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Execute Multiple Statements

 Separated by semicolon ;
 Could return one or more results

 Example:
– "SELECT NOW(); SELECT CURRENT_USER()"

 Needs multi argument set to True
– Raises error if not
– cur.execute(query, multi=True)

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Executing Multiple Statements
Example
cur = cnx.cursor()
queries = "SELECT NOW(); SELECT CURRENT_USER()"
for mcur in cur.execute(query, multi=True):
if mcur.with_rows:
print(mcur.fetchall())

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Retrying a Transaction (1/2)
Using reconnect()
tries = 10
while tries:
tries -= 1
try:
if not cnx.is_connected():
cnx.reconnect()
cur = cnx.cursor()
cur.execute(insert, ('Joe',))
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Retrying a Transaction (2/2)
Using reconnect()
cur.execute(insert, ('Joe',))
except mysql.connector.Error as err:
if not tries:
raise
else:
cnx.commit()
break

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Some Performance Tips

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Push Work to Server
General tips
 Use MySQL functions
– Date/Time calculation,

– String operations, etc..

 Sorting using ORDER BY in queries
 Select what you need
– Don't SELECT *

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Push Work to Server: Example
Date calculation done by MySQL server
query =
"SELECT DATEDIFF( end, start) FROM events WHERE id = %s"
cur.execute(query, (1234,))
event_length = cur.fetchone()[0]

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Raw Data

 Use a raw cursor
– cnx.cursor(raw=True)

 No MySQL to Python conversion
– data are all strings

 It is faster in most cases
– dumping to CSV or create XML
– handle conversion elsewhere

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Bulk Load Using CSV

 Use LOAD DATA LOCAL INFILE
 Server configuration has to allow it
– local_infile=1

 Client flag has to be set

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Using LOAD DATA LOCAL INFILE

CONFIG = {
'user': 'root', 'host': 'fk.example.com',
'client_flags': [mysql.connector.ClientFlag.LOCAL_FILES]
}
sql = "LOAD DATA LOCAL INFILE %s INTO TABLE employees"
cur.execute(sql, ('employees.csv',))

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Frameworks and
Applications

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MySQL Projects
Depending on Connector/Python
 MySQL Utilities
– Command line utilities

– Managing, dumping data, failover, ..

 MySQL Fabric
– Data distribution

– High-availability for groups of MySQL servers
 Both pure Python & no 3rd party modules

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SQLAlchemy

 SQL Toolkit and ORM (Object Relational Mapper)
 Pythonic database access

 Used by lots of other (web) frameworks
 Connector/Python dialect included
– Since SQLAlchemy 0.6

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SQLAlchemy: Usage
Connect String
from sqlalchemy import create_engine
DB_URI =
"mysql+mysqlconnector://{user}:{pwd}@{host}:{port}/{db}"
engine = create_engine(DB_URI.format(
user='joe', pwd='mysecret', db='employees',
host='127.0.0.1', port=3306)
)
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Django

 Web framework
 ORM and database API

 No support for Connector/Python
 But Connector/Python 1.1.1 supports Django
– Support features as microsecond precision
– Works with Django 1.4 and 1.5
– Python 3 support

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Django: Configuration
Using Connector/Python backend
# settings.py
DATABASES = {
'default': {
'ENGINE': 'mysql.connector.django',
}
}

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Q&A

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Q&A
More Information
 Documentation & Examples
– http://dev.mysql.com/doc/connector-python/en/index.html

 Download
– http://dev.mysql.com/downloads/connector/python/#downloads

 Blog
– http://geert.vanderkelen.org

 Feedback & Forum
– http://forums.mysql.com/list.php?50
– http://bugs.mysql.com/

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