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Need help tuning SQL query

My mysql DB became a hungry processor, trying to execute a particularly slow query. When I explain, mysql says "Use where: use temporary, using file management." Please help decrypt and solve this riddle.

Table structure:

CREATE TABLE `topsources` (
  `USER_ID` varchar(255) NOT NULL,
   `UPDATED_TIME` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  `URL_ID` int(11) NOT NULL,
  `SOURCE_SLUG` varchar(100) NOT NULL,
  `FEED_PAGE_URL` varchar(255) NOT NULL,
  `CATEGORY_SLUG` varchar(100) NOT NULL,
  `REFERRER` varchar(2048) DEFAULT NULL,
  PRIMARY KEY (`USER_ID`,`URL_ID`),
  KEY `USER_ID` (`USER_ID`),
  KEY `FEED_PAGE_URL` (`FEED_PAGE_URL`),
  KEY `SOURCE_SLUG` (`SOURCE_SLUG`),
  KEY `CATEGORY_SLUG` (`CATEGORY_SLUG`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

The table has 370K rows ... sometimes higher. The next query takes 10 + seconds.

SELECT topsources.SOURCE_SLUG, COUNT(topsources.SOURCE_SLUG) AS VIEW_COUNT
FROM topsources
WHERE CATEGORY_SLUG = '/newssource'
GROUP BY topsources.SOURCE_SLUG
HAVING MAX(CASE WHEN topsources.USER_ID = 'xxxx' THEN 1 ELSE 0 END) = 0
ORDER BY VIEW_COUNT DESC;

Here is an extended explanation:

+----+-------------+------------+------+---------------+---------------+---------+-------+--------+----------+----------------------------------------------+
| id | select_type | table      | type | possible_keys | key           | key_len | ref   | rows   | filtered | Extra                                        |
+----+-------------+------------+------+---------------+---------------+---------+-------+--------+----------+----------------------------------------------+
|  1 | SIMPLE      | topsources | ref  | CATEGORY_SLUG | CATEGORY_SLUG | 302     | const | 160790 |   100.00 | Using where; Using temporary; Using filesort |
+----+-------------+------------+------+---------------+----

----------- + --------- + ------- + -------- + -------- - + - --------------------------------------------- +

Is there any way to improve this query? Also, are there any mysql settings that can help reduce CPU load? I can allocate more memory available on my server.

+5
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4

CATEGORY_SLUG, . ( , .) , - 10 .

, HAVING .

, ?

+1

, sql

SELECT topsources.SOURCE_SLUG, COUNT(topsources.SOURCE_SLUG) AS VIEW_COUNT
FROM topsources
WHERE CATEGORY_SLUG = '/newssource' and 
    topsources.SOURCE_SLUG not in (
        select distinct SOURCE_SLUG 
        from topsources 
        where USER_ID = 'xxxx'
        )
GROUP BY topsources.SOURCE_SLUG
ORDER BY VIEW_COUNT DESC;
0

If there are many lines that match your CATEGORY_SLUG criteria, it may be difficult to do it quickly, but is it faster?

SELECT ts.SOURCE_SLUG, COUNT(ts.SOURCE_SLUG) AS VIEW_COUNT 
FROM topsources ts
WHERE ts.CATEGORY_SLUG = '/newssource' 
  AND NOT EXISTS(SELECT 1 FROM topsources ts2
                 WHERE ts2.CATEGORY_SLUG = '/newssource'
                   AND ts.SOURCE_SLUG = TS2.SOURCE_SLUG
                   AND ts2.USER_ID = 'xxxx')
GROUP BY ts.SOURCE_SLUG 
ORDER BY VIEW_COUNT DESC;
0
source

It is always difficult to optimize something when you cannot just throw queries into the data yourself, but this would be my first attempt if I did this myself:

SELECT t.SOURCE_SLUG, COUNT(t.SOURCE_SLUG) AS VIEW_COUNT
FROM topsources t
LEFT JOIN (
    SELECT SOURCE_SLUG
    FROM topsources t
    WHERE CATEGORY_SLUG = '/newssource'
    AND USER_ID = 'xxx'
    GROUP BY .SOURCE_SLUG
) x USING (SOURCE_SLUG)
WHERE t.CATEGORY_SLUG = '/newssource'
AND x.SOURCE_SLUG IS NULL
GROUP BY t.SOURCE_SLUG
ORDER BY VIEW_COUNT DESC;
0
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