剖析Mysql表读写、索引等操作的sql语句效率优化问题
发布时间：2022-03-11 21:59:29 所属栏目：编程 来源：互联网
导读：上次我们说到mysql的一些sql查询方面的优化，包括查看explain执行计划，分析索引等等。今天我们分享一些 分析mysql表读写、索引等等操作的sql语句。 闲话不多说，直接上代码： 反映表的读写压力 SELECT file_name AS file, count_read, sum_number_of_bytes_
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上次我们说到mysql的一些sql查询方面的优化，包括查看explain执行计划，分析索引等等。今天我们分享一些 分析mysql表读写、索引等等操作的sql语句。 闲话不多说，直接上代码： 反映表的读写压力 SELECT file_name AS file, count_read, sum_number_of_bytes_read AS total_read, count_write, sum_number_of_bytes_write AS total_written, (sum_number_of_bytes_read + sum_number_of_bytes_write) AS total FROM performance_schema.file_summary_by_instance ORDER BY sum_number_of_bytes_read+ sum_number_of_bytes_write DESC; 反映文件的延迟 SELECT (file_name) AS file, count_star AS total, CONCAT(ROUND(sum_timer_wait / 3600000000000000, 2), 'h') AS total_latency, count_read, CONCAT(ROUND(sum_timer_read / 1000000000000, 2), 's') AS read_latency, count_write, CONCAT(ROUND(sum_timer_write / 3600000000000000, 2), 'h')AS write_latency FROM performance_schema.file_summary_by_instance ORDER BY sum_timer_wait DESC; table 的读写延迟 SELECT object_schema AS table_schema, object_name AS table_name, count_star AS total, CONCAT(ROUND(sum_timer_wait / 3600000000000000, 2), 'h') as total_latency, CONCAT(ROUND((sum_timer_wait / count_star) / 1000000, 2), 'us') AS avg_latency, CONCAT(ROUND(max_timer_wait / 1000000000, 2), 'ms') AS max_latency FROM performance_schema.objects_summary_global_by_type ORDER BY sum_timer_wait DESC; 查看表操作频度 SELECT (DIGEST_TEXT) AS query, SCHEMA_NAME AS db, IF(SUM_NO_GOOD_INDEX_USED > 0 OR SUM_NO_INDEX_USED > 0, '*', '') AS full_scan, COUNT_STAR AS exec_count, SUM_ERRORS AS err_count, SUM_WARNINGS AS warn_count, (SUM_TIMER_WAIT) AS total_latency, (MAX_TIMER_WAIT) AS max_latency, (AVG_TIMER_WAIT) AS avg_latency, (SUM_LOCK_TIME) AS lock_latency, format(SUM_ROWS_SENT,0) AS rows_sent, ROUND(IFNULL(SUM_ROWS_SENT / NULLIF(COUNT_STAR, 0), 0)) AS rows_sent_avg, SUM_ROWS_EXAMINED AS rows_examined, ROUND(IFNULL(SUM_ROWS_EXAMINED / NULLIF(COUNT_STAR, 0), 0)) AS rows_examined_avg, SUM_CREATED_TMP_TABLES AS tmp_tables, SUM_CREATED_TMP_DISK_TABLES AS tmp_disk_tables, SUM_SORT_ROWS AS rows_sorted, SUM_SORT_MERGE_PASSES AS sort_merge_passes, DIGEST AS digest, FIRST_SEEN AS first_seen, LAST_SEEN as last_seen FROM performance_schema.events_statements_summary_by_digest d where d ORDER BY SUM_TIMER_WAIT DESC limit 20; 掌握这些sql，你能轻松知道你的库那些表存在问题，然后考虑怎么去优化。 （编辑：核心网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
