SQL感覚ã§HiveQLを書ãã¨ç—›ã„ç›®ã«ã‚ã†ä¾‹ - still deeperHadoop Advent Calendar 2013 4日目ã®è¨˜äº‹ã§ã™ tl;dr explainã¨job historyã‚’èªã‚ 1 reducerã¯æ‚ª data skewã¯æ‚ª å‰æ›¸ã ã¿ã‚“ãªå¤§å¥½ãSQLã§Hadoop上ã§ã®å‡¦ç†ã‚’実行ã§ãã‚‹Hiveã«ã¯ã¿ãªã•ã‚“普段ã‹ã‚‰ãŠä¸–話ã«ãªã£ã¦ã„ã‚‹ã“ã¨ã§ã—ょã†ã€‚ã¡ã‚‡ã£ã¨èª¿ã¹ç‰©ã§ã‚°ã‚°ã‚‹åº¦ã«ç›®ã«å…¥ã‚‹æ„›ã‚‰ã„ã—ã„マスコットãŒã€è’ã‚“ã 心ã«æ¸…涼ãªé¢¨ã‚’ã¯ã“ã‚“ã§ãã‚Œã¾ã™ã€‚ ã§ã™ãŒHiveã®ã‚¯ã‚¨ãƒªè¨€èªžã¯SQLã§ã¯ãªãHiveQLã§ã™ã—ã€å®Ÿè¡Œã‚¨ãƒ³ã‚¸ãƒ³ã‚‚RDBã®ãã‚Œã¨ã¯å…¨ãç•°ãªã‚‹MapReduceã§ã™ã€‚SQLã®ã¤ã‚‚ã‚Šã§HiveQLを書ã„ã¦ã„ã‚‹ã¨åœ°é›·ã‚’è¸ã‚“ã§ã—ã¾ã†ã“ã¨ãŒã¾ã‚Œã«ã‚ˆãã‚ã‚Šã¾ã™ã€‚本エントリã§ã¯é™¥ã‚ŠãŒã¡ãªHiveQLã®è½ã¨ã—ç©´ã‚’2ã¤ç´¹ä»‹ã—ã¾ã™ã€‚ 例1 SELECT count(DISTINCT user_id) FROM access_log SQLã«æ…£ã‚ŒãŸæ–¹ã§ã‚ã‚Œ
{{#tags}}- {{label}}
{{/tags}}