WebMar 1, 2014 · I don't understand why an order by with a limit is so much slower than just an order by. If I have the follow query it takes about 250 ms: (There are multiple similar queries in the same format). This uses order by AND limit. WebSep 11, 2024 · mysql limit工作原理及order by效率分析. 发布于2024-09-11 20:22:39 阅读 5.3K 0. MySQL 的limit m n工作原理就是先读取前面m+n条记录,然后抛弃前m条,读后 …
mysql--大数据表order by + limit 导致查询缓慢问题 - 冬藏 - 博客园
WebNov 18, 2013 · The limit is always applied at the end of result gathering, therefore after order by. So you will get the closest record <= publishedOn matching all the conditions in the WHERE clause. Just wanted to point out the in case of MySQL ordering is applied before limiting the results. But this is not true for other DB. Web8.2.1.19 LIMIT Query Optimization. If you need only a specified number of rows from a result set, use a LIMIT clause in the query, rather than fetching the whole result set and throwing away the extra data. MySQL sometimes optimizes a query that has a LIMIT row_count clause and no HAVING clause: marine searchlight manufacturers
mysql--大数据表order by + limit 导致查询缓慢问题 - CSDN …
Webselect t.article from (select article, publish_date from table1 order by publish_date desc limit 10) t order by t.publish_date asc; If you need all columns, it is done this way: select t.* … WebApr 3, 2024 · It might work nicely during testing but the order is indeterminate and could break later. Use an order by. SELECT * FROM table1 ORDER BY id LIMIT 5. By the way, another way of getting the last 3 rows is to reverse the order and select the first three rows: SELECT * FROM table1 ORDER BY id DESC LIMIT 3. This will always work even if the … Web可以看到,带 LIMIT 与不带 LIMIT 的结果与我预期的不一样,而且“很不可思议”,真是百思不得其解。 后来百度了一下,如果 order by 的列有相同的值时,MySQL 会随机选取这些 … marine searchlight