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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.
Is there a way to find long running queries in MySQL?
Another valuable tool in MySQL is the included slow query logging feature. This feature is the preferred method for finding long-running queries regularly. There are several directives available to adjust this feature. However, the most commonly needed settings are:
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.
How long does it take to select records in MySQL?
The answer, in my opinion, is quite simple: 5 seconds is the (really low, indeed) time to let 336.052 records travels along the path: MySQL engine => MySQL client libraries => PHP MySQL module => Apache => Network => your PC TCP/IP stack => Browser => DOM parser/builder/etc. => Rendered HTML page.
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.
Why is SQL Server taking too much time to execute?
If this is not possible, then you will continue to suffer performance issues as the engine is busy pulling in rows which are subsequently thrown away. This impacts your i/o, cpu, and, ultimately, the execution plan.
Why does SQL Server take so long to scan a table?
This procedure might take much longer than scanning the table itself: “Table Scan”. but based on the statistics that sql-server has, in such situations, it might not use your index at all.