The quickest way to find tables with full table scan is to query the sys.schema_tables_with_full_table_scans view. Full table scans are resource-intensive and degrade your database performance. For additional information about the types of indexes and how to optimize them, you can refer to this article: How to troubleshoot query performance. With the default 125 GB of provisioned storage, my IO latency is about 15 seconds.īecause Azure Database for MySQL scales IO with respect to storage, after increasing my provisioned storage to 1 TB, my IO latency reduces to 571 ms.ĭespite careful planning, many queries can still result in full table scans. We can find out the average IO latency by querying the sys.user_summary_by_file_io view. IO is the most expensive operation in the database. Performance tuning sys.user_summary_by_file_io To begin with, we'll group the usage patterns into two categories: Performance tuning and Database maintenance. Now let's look at some common usage patterns of the sys_schema. Wait: Wait events grouped by host or user.Examples are file I/Os, connections, and memory. User: Resources consumed and grouped by users.Statement: Information on SQL statements it can be statement that resulted in full table scan, or long query time.Schema: Schema-related information, such as auto increment, indexes, etc.Memory: Memory usage by the host and users.InnoDB: InnoDB buffer status and locks.Host_summary or IO: I/O related latencies.There are 52 views in the sys_schema, and each view has one of the following prefixes: Building on both performance_schema and information_schema, the sys_schema provides a powerful collection of user-friendly views in a read-only database and is fully enabled in Azure Database for MySQL version 5.7. However, the performance_schema contains more than 80 tables, and getting the necessary information often requires joining tables within the performance_schema, and tables from the information_schema. The MySQL performance_schema, first available in MySQL 5.5, provides instrumentation for many vital server resources such as memory allocation, stored programs, metadata locking, etc. For more information about migrating to Azure Database for MySQL - Flexible Server, see What's happening to Azure Database for MySQL Single Server? We strongly recommend for you to upgrade to Azure Database for MySQL - Flexible Server. Azure Database for MySQL - Single Server is on the retirement path.
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