This was an experiment, trying to parse the XML dump of stackoverflow into a mysql database. Unfortuently, the script failed once the XML dumps got large enough.

PyOverflow.py

from lxml import etree
import pymysql

def fast_iter(context, func):
    for event, elem in context:
        func(elem)
        elem.clear()
        while elem.getprevious() is not None:
            del elem.getparent()[0]
    del context


# Since most of the functions are all alike, this is a nice way to generate the functions.
def process_sqldump(arr):
    return lambda elem: arr.append(elem.items())

db = pymysql.connect(host="localhost", user="dev", passwd="xyz", charset="utf8")
c = db.cursor()

# The main def.
def main(folder, dbname):
    # The items.
    badges = []
    comments = []
    posthistory = []
    posts = []
    users = []
    votes = []


    # Having the infiles paired with their arrays make for easy looping later.
    infiles = (('{}/Badges.xml'.format(folder), badges),
               ('{}/Comments.xml'.format(folder), comments),
               ('{}/PostHistory.xml'.format(folder), posthistory),
               ('{}/Posts.xml'.format(folder), posts),
               ('{}/Users.xml'.format(folder), users),
               ('{}/Votes.xml'.format(folder), votes))

    tables = ('badges',
              'comments',
              'posthistory',
              'posts',
              'users',
              'votes')

    create_tables = '''
    CREATE TABLE IF NOT EXISTS `badges` (
      `Id` INT NOT NULL AUTO_INCREMENT,
      `UserId` INT NOT NULL,
      `Name` VARCHAR(50) NOT NULL,
      `Date` DATETIME NOT NULL,
      PRIMARY KEY (`Id`))
    ENGINE = InnoDB;

    CREATE TABLE IF NOT EXISTS `users` (
      `Id` INT NOT NULL AUTO_INCREMENT,
      `Reputation` INT NOT NULL DEFAULT 1,
      `CreationDate` DATETIME NOT NULL,
      `DisplayName` VARCHAR(45) NOT NULL,
      `LastAccessDate` DATETIME NOT NULL,
      `WebsiteUrl` VARCHAR(70) NULL,
      `Location` VARCHAR(45) NULL,
      `AboutMe` MEDIUMTEXT NULL,
      `Views` INT NULL DEFAULT 0,
      `UpVotes` INT NULL DEFAULT 0,
      `DownVotes` INT NULL DEFAULT 0,
      `ProfileImageUrl` VARCHAR(100) NULL,
      `EmailHash` VARCHAR(45) NULL,
      `Age` TINYINT UNSIGNED NULL,
      PRIMARY KEY (`Id`))
    ENGINE = InnoDB;

    CREATE TABLE IF NOT EXISTS `comments` (
      `Id` INT NOT NULL AUTO_INCREMENT,
      `PostId` INT NOT NULL,
      `Score` INT NULL,
      `Text` MEDIUMTEXT NOT NULL,
      `CreationDate` DATETIME NOT NULL,
      `UserId` INT NULL,
      PRIMARY KEY (`Id`))
    ENGINE = InnoDB;

    CREATE TABLE IF NOT EXISTS `posts` (
      `Id` INT NOT NULL AUTO_INCREMENT,
      `PostTypeId` TINYINT NOT NULL,
      `AcceptedAnswerId` INT NULL,
      `ParentId` INT NULL,
      `CreationDate` DATETIME NOT NULL,
      `Score` INT NOT NULL,
      `ViewCount` INT NULL,
      `Body` LONGTEXT NOT NULL,
      `OwnerUserId` INT NULL,
      `LastEditorUserId` INT NULL,
      `LastEditDate` DATETIME NULL,
      `LastActivityDate` DATETIME NULL,
      `AnswerCount` INT NULL,
      `CommentCount` INT NULL,
      `FavoriteCount` INT NULL,
      PRIMARY KEY (`Id`))
    ENGINE = InnoDB;

    CREATE TABLE IF NOT EXISTS `votes` (
      `Id` INT NOT NULL AUTO_INCREMENT,
      `PostId` INT NOT NULL,
      `VoteTypeId` INT NOT NULL,
      `UserId` INT NULL,
      `CreationDate` DATETIME NOT NULL,
      PRIMARY KEY (`Id`))
    ENGINE = InnoDB;

    CREATE TABLE IF NOT EXISTS `posthistory` (
      `Id` INT NOT NULL AUTO_INCREMENT,
      `PostHistoryTypeId` INT NOT NULL,
      `PostId` INT NOT NULL,
      `RevisionGUID` VARCHAR(36) NULL,
      `CreationDate` DATETIME NULL,
      `UserDisplayName` VARCHAR(45) NULL,
      `UserId` INT NULL,
      `Comment` MEDIUMTEXT NULL,
      `Text` MEDIUMTEXT NULL,
      PRIMARY KEY (`Id`))
    ENGINE = InnoDB;
    '''

    for infile, arr in infiles:
        context = etree.iterparse(infile, tag='row')
        fast_iter(context, process_sqldump(arr))

    # Creat schema
    c.execute('DROP SCHEMA IF EXISTS {}'.format(dbname))
    c.execute('CREATE SCHEMA {} CHARACTER SET utf8'.format(dbname))
    c.execute('USE {}'.format(dbname))

    # We don't need the existing tables.
    for table in tables:
        c.execute('DROP TABLE IF EXISTS {}'.format(table))

    # We need the tables
    c.execute(create_tables)


    # This section is going to be all about formatting the data for
    # clean sql insertion.
    badgesSQL = []
    for elem in badges:
        elemdict = dict(elem)
        t = (elemdict['Id'], elemdict['UserId'], elemdict['Name'], elemdict['Date'])
        badgesSQL.append(t)

    usersSQL = []
    for elem in users:
        # Since not all rows contain all the attributes, using a dict is a very
        # good solution, as we get the dict.get() method.
        elemdict = dict(elem)
        t = (elemdict['Id'],
            elemdict['Reputation'],
            elemdict['CreationDate'],
            elemdict['DisplayName'],
            elemdict['LastAccessDate'],
            elemdict.get('WebsiteUrl'),
            elemdict.get('Location'),
            elemdict.get('AboutMe'),
            elemdict['Views'],
            elemdict['UpVotes'],
            elemdict['DownVotes'],
            elemdict.get('ProfileImageUrl'),
            elemdict.get('EmailHash'),
            elemdict.get('Age'))
        usersSQL.append(t)

    commentsSQL = []
    for elem in comments:
        elemdict = dict(elem)
        t = (elemdict['Id'],
            elemdict['PostId'],
            elemdict.get('Score', 0),
            elemdict['Text'],
            elemdict['CreationDate'],
            elemdict.get('UserId'))
        commentsSQL.append(t)

    postsSQL = []
    for elem in posts:
        elemdict = dict(elem)
        t = (elemdict['Id'],
            elemdict['PostTypeId'],
            elemdict.get('AcceptedAnswerId'),
            elemdict.get('ParentId'),
            elemdict['CreationDate'],
            elemdict.get('Score'),
            elemdict.get('ViewCount'),
            elemdict['Body'],
            elemdict.get('OwnerUserId'),
            elemdict.get('LastEditorUserId'),
            elemdict.get('LastEditDate'),
            elemdict.get('LastActivityDate'),
            elemdict.get('AnswerCount'),
            elemdict.get('CommentCount'),
            elemdict.get('FavoriteCount'))
        postsSQL.append(t)

    votesSQL = []
    for elem in votes:
        elemdict = dict(elem)
        t = (elemdict['Id'],
            elemdict['PostId'],
            elemdict['VoteTypeId'],
            elemdict.get('UserId'),
            elemdict['CreationDate'])
        votesSQL.append(t)

    posthistorySQL = []
    for elem in posthistory:
        elemdict = dict(elem)
        t = (elemdict['Id'],
            elemdict['PostHistoryTypeId'],
            elemdict['PostId'],
            elemdict['RevisionGUID'],
            elemdict['CreationDate'],
            elemdict.get('UserDisplayName'),
            elemdict.get('UserId'),
            elemdict.get('Comment'),
            elemdict.get('Text'))
        posthistorySQL.append(t)



    # Here the actual insertion takes place.

    # Users
    c.executemany('''INSERT INTO `users`
    (`Id`, `Reputation`, `CreationDate`, `DisplayName`, `LastAccessDate`,
     `WebsiteUrl`, `Location`, `AboutMe`, `Views`, `UpVotes`, `DownVotes`,
     `ProfileImageUrl`, `EmailHash`, `Age`)
      VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)''', usersSQL)

    db.commit()

    # Badges
    c.executemany("""INSERT INTO badges (Id, Userid, Name, Date)
        VALUES (%s, %s, %s, %s)""", badgesSQL)

    db.commit()

    # Comments
    c.executemany('''INSERT INTO `comments`
    (`Id`, `PostId`, `Score`, `Text`, `CreationDate`, `UserId`)
    VALUES (%s, %s, %s, %s, %s, %s)''', commentsSQL)

    db.commit()

    # Posts
    c.executemany('''INSERT INTO `posts`
    (`Id`,
    `PostTypeId`,
    `AcceptedAnswerId`,
    `ParentId`,
    `CreationDate`,
    `Score`,
    `ViewCount`,
    `Body`,
    `OwnerUserId`,
    `LastEditorUserId`,
    `LastEditDate`,
    `LastActivityDate`,
    `AnswerCount`,
    `CommentCount`,
    `FavoriteCount`)
    VALUES
    (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)''', postsSQL)

    db.commit()

    # Votes
    c.executemany('''INSERT INTO `votes`
    (`Id`, `PostId`, `VoteTypeId`, `UserId`, `CreationDate`) VALUES
    (%s, %s, %s, %s, %s)''', votesSQL)

    db.commit()

    # Post History
    c.executemany('''INSERT INTO `posthistory`
    (`Id`, `PostHistoryTypeId`, `PostId`, `RevisionGUID`, `CreationDate`,
    `UserDisplayName`, `UserId`, `Comment`, `Text`)
    VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s)''', posthistorySQL)

    # Sincr we are using InnoDB we need to do this.
    db.commit()

    # Close up the DB

#main('meta.sharepoint.stackexchange.com', 'metasharepointstackexchangecom')
main('superuser.com', 'superuser')