Why Index could refuse to work ?

Have you ever seen index which refused to be used even if there is every reason for it to work (from the glance view):


mysql> explain select * from article where article_id=10;
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | […]

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MySQL ORDER BY LIMIT Performance Optimization


Suboptimal MySQL ORDER BY implementation, especially together with LIMIT is often the cause of MySQL performance problems. Here is what you need to know about MySQL ORDER BY LIMIT optimization to avoid these problems.
MySQL ORDER BY with LIMIT is the most common use of ORDER BY in interactive applications with large data sets being sorted. […]

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