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What makes query slow?
Slow queries can mean your database does more work than it needs to, which means it’s using more resources than it needs to. When limited resources like CPU or I/O run out, everything can start to slow down. Inefficient use of resources is also a problem when you’re not using the resources you have.
Why is my database so slow?
Troubleshooting Slow Servers. Missing indexes, an inadequate storage I/O subsystem, or a slow network are only some of the possible reasons why a SQL Server database engine might slow down, which is why finding the true cause of a performance bottleneck is vital. Poor index design. Poorly designed database schema.
Where to put slow query logs in MySQL?
You must ensure that the variable slow_query_log is set to ON, while the slow_query_log_file determines the path where you need to place your slow query logs. If this variable is not set, it will use the DATA_DIR of your MySQL data directory.
Why is SQL query with where so slow?
So when I change the query to this it takes 7 minutes to execute: Why would this make the query time go up from 1 sec to 7 mins? Since the b table is huge I even tried to use CTE but that did not improve the performance either. I thought with the CTE there will be smaller set of values to filter from so it should be faster but that did not help:
Are there any performance issues with MySQL database?
Performance issues are common problems when administering MySQL databases. Sometimes these problems are, in fact, due to slow queries. In this blog, we’ll deal with slow queries and how to identify these. MySQL has the capability to filter and log slow queries.
Can a 10 second query cause performance degradation?
The slow queries definition might differ in different cases since there are certain occasions that even a 10 second query is acceptable and still not slow. However, if your application is an OLTP, it’s very common that a 10 second or even a 5 second query is an issue or causes performance degradation to your database.