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Why MySQL is so fast?
To function, a database server needs four fundamental resources: CPU, memory, disk, and network. Another good example of this balance pertains to CPUs. In most cases, MySQL will perform well with fast CPUs because each query runs in a single thread and can’t be parallelized across CPUs.
What should the slow query time be in MySQL?
MySQL has a built-in slow query log. To use it, open the my.cnf file and set the slow_query_log variable to “On.” Set long_query_time to the number of seconds that a query should take to be considered slow, say 0.2.
Why is select all so slow in SQL?
If the data has tons of fields and rows, “select all” will tax the database resources and slow the entire system down. Your query will grind to a halt: data overload.
When to turn off the slow query log?
The slow query log should only remain enabled for a specific duration when actively looking for troublesome queries that may be impacting the application or website.
Is there such thing as super slow query syndrome?
Your boss calls it “sequel,” but you’ve been calling it S-Q-L for months. And that’s not the worst. You’re suffering from “Super Slow Query Syndrome,” and sometimes, your queries bomb without a result. Don’t worry.
Why are MySQL queries so slow on my server?
When we detect slow queries in our customer’s servers, we resolve it by: Resource optimization – In many cases, slow queries are caused by resource limits or unoptimized MySQL settings. Our first action is to look for an fix such resource issues.
The slow query log should only remain enabled for a specific duration when actively looking for troublesome queries that may be impacting the application or website.
Why is MySQL running on a low memory?
MySQL is then forced to run on a very low available memory and I/O, causing it to use the disk-based Swap memory, thereby slowing down the server. Ideally MySQL should run in its own independent server. However, this is not economical. So, you might run related services together – such as Web, DNS and MySQL.
Is it slow to use in with subqueries?
Yes, IN with subqueries is slow. Use a join instead. And make sure you’ve defined indexes on em_link_data.linkid and em_link.id.