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。

闲话不多说，直接上代码：

反映表的读写压力

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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

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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

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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

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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.<a name="baidusnap0"></a><strong style="color: black; ">table_io_waits_summary_by_</strong>table     ORDER BY sum_timer_wait DESC ;

索引状况

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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.<strong style="color: black; ">table_io_waits_summary_by_</strong>index_usage WHERE index_name IS NOT NULL ORDER BY sum_timer_wait DESC;

全表扫描情况

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SELECT object_schema,     object_name,     count_read AS rows_full_scanned  FROM performance_schema.<strong style="color: black; ">table_io_waits_summary_by_</strong>index_usage WHERE index_name IS NULL   AND count_read > 0 ORDER BY count_read DESC;

没有使用的index

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SELECT object_schema,     object_name,     index_name   FROM performance_schema.<strong style="color: black; ">table_io_waits_summary_by_</strong>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

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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;