Script to import the stackexchange dumps into MySQL

stackoverflow.sql

# Copyright (c) 2013 Georgios Gousios
# MIT-licensed

create database stackoverflow DEFAULT CHARACTER SET utf8 DEFAULT COLLATE utf8_general_ci;

use stackoverflow;

create table badges (
  Id INT NOT NULL PRIMARY KEY,
  UserId INT,
  Name VARCHAR(50),
  CreationDate DATETIME
);

CREATE TABLE comments (
    Id INT NOT NULL PRIMARY KEY,
    PostId INT NOT NULL,
    Score INT NOT NULL DEFAULT 0,
    Text TEXT,
    CreationDate DATETIME,
    UserId INT NOT NULL
);

CREATE TABLE post_history (
    Id INT NOT NULL PRIMARY KEY,
    PostHistoryTypeId SMALLINT NOT NULL,
    PostId INT NOT NULL,
    RevisionGUID VARCHAR(36),
    CreationDate DATETIME,
    UserId INT NOT NULL,
    Text TEXT
);

CREATE TABLE posts (
    Id INT NOT NULL PRIMARY KEY,
    PostTypeId SMALLINT,
    AcceptedAnswerId INT,
    ParentId INT,
    Score INT NULL,
    ViewCount INT NULL,
    Body text NULL,
    OwnerUserId INT NOT NULL,
    LastEditorUserId INT,
    LastEditDate DATETIME,
    LastActivityDate DATETIME,
    Title varchar(256) NOT NULL,
    Tags VARCHAR(256),
    AnswerCount INT NOT NULL DEFAULT 0,
    CommentCount INT NOT NULL DEFAULT 0,
    FavoriteCount INT NOT NULL DEFAULT 0,
    CreationDate DATETIME
);

CREATE TABLE users (
    Id INT NOT NULL PRIMARY KEY,
    Reputation INT NOT NULL,
    CreationDate DATETIME,
    DisplayName VARCHAR(50) NULL,
    LastAccessDate  DATETIME,
    Views INT DEFAULT 0,
    WebsiteUrl VARCHAR(256) NULL,
    Location VARCHAR(256) NULL,
    AboutMe TEXT NULL,
    Age INT,
    UpVotes INT,
    DownVotes INT,
    EmailHash VARCHAR(32)
);

CREATE TABLE votes (
    Id INT NOT NULL PRIMARY KEY,
    PostId INT NOT NULL,
    VoteTypeId SMALLINT,
    CreationDate DATETIME
);

load xml infile 'Badges.xml'
into table badges
rows identified by '<row>';

load xml infile 'Comments.xml'
into table comments
rows identified by '<row>';

load xml infile 'PostHistory.xml'
into table post_history
rows identified by '<row>';

load xml infile 'Posts.xml'
into table posts
rows identified by '<row>';

load xml infile 'Users.xml'
into table users
rows identified by '<row>';

load xml infile 'Votes.xml'
into table votes
rows identified by '<row>';

create index badges_idx_1 on badges(UserId);

create index comments_idx_1 on comments(PostId);
create index comments_idx_2 on comments(UserId);

create index post_history_idx_1 on post_history(PostId);
create index post_history_idx_2 on post_history(UserId);

create index posts_idx_1 on posts(AcceptedAnswerId);
create index posts_idx_2 on posts(ParentId);
create index posts_idx_3 on posts(OwnerUserId);
create index posts_idx_4 on posts(LastEditorUserId);

create index votes_idx_1 on votes(PostId);

unespace.rb

#!/usr/bin/env ruby
# Copyright (c) 2013 Georgios Gousios
# MIT-licensed

require 'sequel'
require 'mysql2'
require 'cgi'

Sequel::Database.extension :pagination
DB = Sequel.connect("mysql2://#{ARGV[1]}:#{ARGV[2]}@#{ARGV[0]}/#{ARGV[3]}")

table = ARGV[4].to_sym
field = ARGV[5].to_sym

lines = 0
lines_with_escapes = 0

DB.from(table.to_sym).select(:Id, field).each_page(1000) do |page|
  page.each do |row|
    lines += 1
    text = row[field]

    next if text.nil?

    text_unescaped = CGI.unescapeHTML(text)
    if text_unescaped != text
      lines_with_escapes += 1
      DB[table].filter(:Id => row[:Id]).update(field => text_unescaped)
    end

    print "\r #{lines} lines, #{lines_with_escapes} with escapes"
  end
end

zreadme.md

MySQL script to import stackexchange data dumps (as retrieved from here).

The accompanying Ruby script will un-escape various XML-escaped characters that the MySQL import process fails to do.

Two comments if you want to use this;

1. Make sure to add --secure_file_priv= to the mysqld startup options (or secure_file_priv= in my.cnf under [mysqld])
2. Add this to the top of the SQL file; SET @@SESSION.SQL_MODE=''; this is especially important for late 5.7 and 8.0 versions as they have the STRICT_TRANS_TABLES SQL_MODE turned on by default (and this results in 'ERROR 1263 (22004): Column set to default value; NULL supplied to NOT NULL column 'id' at row 1'. For more info, see https://dev.mysql.com/doc/refman/5.7/en/sql-mode.html#sqlmode_strict_trans_tables

Hello from 2020 - one more comment about using nowadays... I would update the statements for the create tables to have CHARACTER SET = utf8; ... might save some trouble for some of these more exotic posts with emojis/symbols.