mysql查看索引利用率
-- mysql查看索引利用率 -- 如果很慢把排序去掉,加上limit 并且在where条件中限定表名。 -- cardinality越接近0,利用率越低 SELECT t.TABLE_SCHEMA, t.TABLE_NAME, INDEX_NAME, CARDINALITY, TABLE_ROWS, CARDINALITY / TABLE_ROWS AS SELECTIVITY FROM information_schema.TABLES t, (SELECT table_schema, table_name, index_name, cardinality FROM information_schema.STATISTICS WHERE ( table_schema, table_name, index_name, seq_in_index ) IN (SELECT table_schema, table_name, index_name, MAX(seq_in_index) FROM information_schema.STATISTICS GROUP BY table_schema, table_name, index_name)) s WHERE t.table_schema = s.table_schema AND t.table_name = s.table_name AND t.table_rows != 0 AND t.table_schema NOT IN ( 'mysql', 'performance_schema', 'information_schema' ) ORDER BY SELECTIVITY ;
作者:天下没有收费的bug
本文版权归作者和博客园共有,欢迎转载,但未经作者同意必须在文章页面给出原文链接,否则保留追究法律责任的权利。