WORDPRESS MYSQL DEADLOCK HOW TO

Several days later I heard back from the Solar winds application engineer stating that they had a script for me to run. I sent the email below to Solar winds support and suggested the Solar winds developer change the query to a read uncommitted. Upon further investigation I noticed the Solarwinds Application Insight for SQL SERVER monitoring application was doing a read committed operation on system tables in all my database. Ever since I turned on the Application Insight feature I started seeing deadlock’s occurring in my SQL SERVER environment. I am running Solarwinds Server application Monitor 11.1 and SQL SERVER Application Insight.

I recently found a bug in the way Solar winds monitor’s our databases.

WORDPRESS MYSQL DEADLOCK HOW TO

Reference: For more in depth informaiton on the the performance schema and A Visual Guide to the MySQL Performance Schema How to handle bulk UPDATE statements in large tables This may indicate that their is a need for an index.Īdditional performance tables can be viewed which present statistics on number of temp tables created.

If there is a large difference between the two. This means that the query optimizer is examining many rows but only sending a a small number. Here it is important to note the difference between the average rows sent and the average rows examined. Instruments can be enabled by running an UPDATE statement on the table.Īfter the performance_schema has been configured you will be able to view the sys tables for statistics collected on queries.įrom sys.`x$statements_with_full_table_scans` To view the current instruments which are enabled run the following query. The setup_actors table determines who to monitor, you can filter by host, user or role. The screen shot below shows that performance stats will be collected for all databases except for mysql, Performance_schema and information_schema. View which objects have the performance schema setup on them. Performance_schema_consumer_events_waits_history_long=ONĬonsumers are setup in the setup_consumers table this specified where the data will go. Performance_schema_consumer_events_waits_history=ON Performance_schema_consumer_events_waits_current=ON Performance_schema_consumer_events_stages_history_long=ON Performance_schema_consumer_events_stages_history=ON Performance_schema_consumer_events_stages_current=ON Performance_schema_consumer_events_statements_history=ON Performance_schema_consumer_events_statements_history_long=ON This can be useful if you want to disable and enable the performance_schema to troubleshoot performance issues then turn them back off without having to restart MySQL. One can also enable the performance_schema by running SQL queries after MySQL is up and running. Setting the performance_schema directives in the mn.cnf file will ensure that the performance_schema is enabled at startup. Therefore be careful when enabling the performance schema in a production environment as it can add a significant amount of overhead. Percona has a good write up on the performance impact of enabling the Performance Schema. Possible reasons why enabling the performance schema is a bad thing includes performance impact on the server. The performance schema can be enabled through several different methods.

However, the performance schema is not enabled by default. The MySQL Performance Schema is an extremely valuable feature in MySQL 5.6 for finding queries which have a performance impact on the database. Scan count 1, logical reads 4, physical reads 0, They replied saying that the query was generated by an Microsoft Access database and they had refactored the query, removing the extra parentheses. I gathered the following information and forwarded it to the customer. Scan count 0, logical reads 0, physical reads 0, Read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Scan count 9, logical reads 207651, physical reads 0, SELECT table1.brcd, table2.Pkt_x, table2.PKT_NBRįROM table1 WITH(NOLOCK) INNER JOIN table2 WITH(NOLOCK) ON table1.PKT_NB = table2.PKT_NB Upon removing these parentheses the query went from 207,651 logical reads to 4. In addition, I noticed that there were extra parentheses around the filters in the WHERE clause. I thought this was interesting in that the query seemed to be very selective with the WHERE clause placed on it. Each time the query below ran it was performing 207,651 logical reads on the server. The query below quickly caught my attention. I logged in and looked at the query plan cache to see which queries were causing load on the server. I had received a high CPU alert from the SQL SERVER 2008 server. Recently I encountered an interesting issue with the SQL SERVER query engine.

Wordpress mysql deadlock