Вчерашний запрос, "заморозивший" миграцию на три часа:
SELECT entity_id, MAX(start_date), MAX(end_date) FROM ( SELECT entity_id, MAX(start_date) start_date, NULL AS end_date FROM audit_log WHERE attr = 'reviewed' AND newValue = 'true' GROUP BY entity_id UNION ALL SELECT entity_id, NULL AS start_date, MAX(end_date) end_date FROM audit_log WHERE attr = 'overriden' AND newValue = 'true' GROUP BY entity_id ) a GROUP BY entity_id;
можно было бы написать сильно оптимальнее вот так:
SELECT entity_id, MAX(if(attr = 'reviewed', NULL, start_date)) AS start_date, MAX(if(attr = 'reviewed', end_date, NULL)) end_date FROM audit_log WHERE (attr = 'reviewed' OR attr='overriden') AND newValue = 'true' GROUP BY entity_id;
При сильно похожих WHERE в таких конструкциях, удобнее схлопнуть UNION и "на лету" подставлять в SELECT нужное значение через if.
Вчерашний запрос, "заморозивший" миграцию на три часа:
SELECT entity_id, MAX(start_date), MAX(end_date) FROM ( SELECT entity_id, MAX(start_date) start_date, NULL AS end_date FROM audit_log WHERE attr = 'reviewed' AND newValue = 'true' GROUP BY entity_id UNION ALL SELECT entity_id, NULL AS start_date, MAX(end_date) end_date FROM audit_log WHERE attr = 'overriden' AND newValue = 'true' GROUP BY entity_id ) a GROUP BY entity_id;
можно было бы написать сильно оптимальнее вот так:
SELECT entity_id, MAX(if(attr = 'reviewed', NULL, start_date)) AS start_date, MAX(if(attr = 'reviewed', end_date, NULL)) end_date FROM audit_log WHERE (attr = 'reviewed' OR attr='overriden') AND newValue = 'true' GROUP BY entity_id;
При сильно похожих WHERE в таких конструкциях, удобнее схлопнуть UNION и "на лету" подставлять в SELECT нужное значение через if.
BY Developer's mind
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Mr. Durov launched Telegram in late 2013 with his brother, Nikolai, just months before he was pushed out of VK, the Russian social-media platform he founded. Mr. Durov pitched his new app—funded with the proceeds from the VK sale—less as a business than as a way for people to send messages while avoiding government surveillance and censorship.
The global forecast for the Asian markets is murky following recent volatility, with crude oil prices providing support in what has been an otherwise tough month. The European markets were down and the U.S. bourses were mixed and flat and the Asian markets figure to split the difference.The TSE finished modestly lower on Friday following losses from the financial shares and property stocks.For the day, the index sank 15.09 points or 0.49 percent to finish at 3,061.35 after trading between 3,057.84 and 3,089.78. Volume was 1.39 billion shares worth 1.30 billion Singapore dollars. There were 285 decliners and 184 gainers.
