分析Mysql表读写、索引等操作的sql语句效率优化问题
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。
成都创新互联公司专注于企业全网整合营销推广、网站重做改版、邵东网站定制设计、自适应品牌网站建设、H5建站、商城网站建设、集团公司官网建设、外贸营销网站建设、高端网站制作、响应式网页设计等建站业务,价格优惠性价比高,为邵东等各大城市提供网站开发制作服务。
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 object_schema AS table_schema, object_name AS table_name, count_star AS rows_io_total, count_read AS rows_read, count_write AS rows_write, count_fetch AS rows_fetchs, count_insert AS rows_inserts, count_update AS rows_updates, count_delete AS rows_deletes, CONCAT(ROUND(sum_timer_fetch / 3600000000000000, 2), 'h') AS fetch_latency, CONCAT(ROUND(sum_timer_insert / 3600000000000000, 2), 'h') AS insert_latency, CONCAT(ROUND(sum_timer_update / 3600000000000000, 2), 'h') AS update_latency, CONCAT(ROUND(sum_timer_delete / 3600000000000000, 2), 'h') AS delete_latency FROM performance_schema.table_io_waits_summary_by_table ORDER BY sum_timer_wait DESC ;
索引状况
SELECT OBJECT_SCHEMA AS table_schema, OBJECT_NAME AS table_name, INDEX_NAME as index_name, COUNT_FETCH AS rows_fetched, CONCAT(ROUND(SUM_TIMER_FETCH / 3600000000000000, 2), 'h') AS select_latency, COUNT_INSERT AS rows_inserted, CONCAT(ROUND(SUM_TIMER_INSERT / 3600000000000000, 2), 'h') AS insert_latency, COUNT_UPDATE AS rows_updated, CONCAT(ROUND(SUM_TIMER_UPDATE / 3600000000000000, 2), 'h') AS update_latency, COUNT_DELETE AS rows_deleted, CONCAT(ROUND(SUM_TIMER_DELETE / 3600000000000000, 2), 'h')AS delete_latency FROM performance_schema.table_io_waits_summary_by_index_usage WHERE index_name IS NOT NULL ORDER BY sum_timer_wait DESC;
全表扫描情况
SELECT object_schema, object_name, count_read AS rows_full_scanned FROM performance_schema.table_io_waits_summary_by_index_usage WHERE index_name IS NULL AND count_read > 0 ORDER BY count_read DESC;
没有使用的index
SELECT object_schema, object_name, index_name FROM performance_schema.table_io_waits_summary_by_index_usage WHERE index_name IS NOT NULL AND count_star = 0 AND object_schema not in ('mysql','v_monitor') AND index_name <> 'PRIMARY' ORDER BY object_schema, object_name;
糟糕的sql问题摘要
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。
总结
以上就是这篇文章的全部内容了,希望本文的内容对大家的学习或者工作具有一定的参考学习价值,谢谢大家对创新互联的支持。如果你想了解更多相关内容请查看下面相关链接
标题名称:分析Mysql表读写、索引等操作的sql语句效率优化问题
标题路径:http://myzitong.com/article/jeehoh.html