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How do I fix a slow database?
Start by checking your wait stats
- Ensure your TempDB database is configured optimally.
- Make sure you’re running index maintenance frequently.
- Implement indexes that provide a benefit to your queries.
- Check your most expensive queries and stored procedures.
- Monitor your performance counters.
What is a slow query?
The slow query log consists of SQL statements that take more than long_query_time seconds to execute and require at least min_examined_row_limit rows to be examined. The slow query log can be used to find queries that take a long time to execute and are therefore candidates for optimization.
Why is MySQL very simple join taking too long?
This query takes too long, and before executing it I was trying to test how long takes this simplier query: It is still taking too long, and I don’t understand why.
Why does MySQL Query take more time than it should?
Check the query more than once. The first run may be too long since the data should be read from the disk into the memory. When you’re running query first time the data is still not in innodb buffer and has to be read from the disk. Which is much slower than if the data would be in cache already.
Why are my query plans taking so long?
Lacking them, the database optimizer/planner has to create a query plan that scans the entire table. While the table is not big, it is not very small either. Adding an index on (firstid, secondid) will improve performance a lot. However 300 seconds looks too long, even for a table scan, so the hardware or the DBMS settings should be examined, too.
How to optimize a query in MySQL?
If you have access to SQL Server, highlight your complete query in SQL server, and click + L This will show the query execution plan. Optimize the query based on these results; if for example you see table scans then an index may assist. Write queries that do not use the term distinct. Do not order results if the order is unimportant.