上次我們說到mysql的一些sql查詢方面的優化，包括查看explain執行計劃，分析索引等等。今天我們分享一些 分析mysql表讀寫、索引等等操作的sql語句。
閑話不多說，直接上代碼：
反映表的讀寫壓力
| 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_instanceORDER BY sum_number_of_bytes_read+ sum_number_of_bytes_write DESC; |
反映文件的延遲
| 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_instanceORDER BY sum_timer_wait DESC; |
table 的讀寫延遲
| 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; |
查看表操作頻度
| 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 ; |
索引狀況
| 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_latencyFROM performance_schema.table_io_waits_summary_by_index_usageWHERE index_name IS NOT NULLORDER BY sum_timer_wait DESC; |
