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  • 深入理解索引系列1:环境搭建

    CREATE SCHEMA IF NOT EXISTS book;
    
    USE book;
    
    CREATE TABLE source_words(
    word VARCHAR(50) NOT NULL,
    INDEX(word)
    )ENGINE=MyISAM;
    
    LOAD DATA LOCAL INFILE 'C:\Users\John\Desktop\source_words.txt' INTO TABLE source_words(word);
    
    SELECT COUNT(*) FROM SOURCE_WORDS;
    
    CREATE TABLE million_words(
    id INT UNSIGNED NOT NULL AUTO_INCREMENT,
    word VARCHAR(50) not null,
    primary key (id),
    UNIQUE INDEX (word)) ENGINE=INNODB;
    
    INSERT INTO million_words(word)
    SELECT DISTINCT word FROM source_words;
    
    INSERT INTO million_words(word)
    SELECT DISTINCT REVERSE(word) FROM source_words WHERE REVERSE(word) NOT IN (SELECT word FROM source_words);
    
    SELECT @cnt := COUNT(*) FROM million_words;
    --59572
    
    SELECT @diff := 1000000- @cnt;
    --940428
    
    
    SET @sql = CONCAT("
    INSERT INTO million_words(word)
    SELECT DISTINCT CONCAT(word,'X1Y') FROM source_words LIMIT",@diff);
    
    PREPARE cmd FROM @sql;
    
    EXECUTE cmd;
    
    SELECT COUNT(*) FROM million_words;
    --89358
    

      

    测试数据链接:

    http://effectivemysql.com/downloads/words

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  • 原文地址:https://www.cnblogs.com/xiaoit/p/4468146.html
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