问题
I have recently completely re-written a large project. In doing so, I have consolidated great number of random MySQL queries. I do remember that over the course of developing the previous codebase, I created indexes on a whim, and I'm sure there are a great number that aren't used anymore.
Is there a way to monitor MySQL's index usage to determine which indexes are being used, and which ones are not?
回答1:
I don't think this information is available in a stock MySQL installation.
Percona makes tools and patches for MySQL to collect index usage data.
See:
- User Statistics (and Index Statistics)
- How expensive is USER_STATISTICS?
- pt-index-usage
See also:
- New INDEX_STATISTICS table in the information_schema
- check-unused-keys: A tool to interact with INDEX_STATISTICS
- New table_io_waits_summary_by_index_usage table in performance_schema in MySQL 5.6
You may also be interested in a Java app called MySQLIndexAnalyzer, which helps to find redundant indexes. But this tool doesn't have any idea which indexes are unused.
来源：https://stackoverflow.com/questions/3243475/how-do-you-identify-unused-indexes-in-a-mysql-database