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Is the memory usage too high in MySQL?
It’s not a dedicated server so there’re other processes running at the same time. Anyway when MySQL daemon is stopped, the maximum memory usage is aprox. 38Gb so MySQL could use up to 25Gb for its own without swapping (way too much IMHO).
How is memory allocated in a MySQL server?
Once memory is allocated, it is not freed until the server is restarted. MySQL can also be configured to allocate large areas of memory for its buffer pool if using Linux and if kernel is enabled for large page support, i.e. using HugePages .
Why is MySQL swapping out its memory to disk?
Either way, it’s probable that MySQL is swapping out its memory to disk. This is oftentimes a very common situation especially when MySQL server and the underlying hardware is not set optimally in parallel to the expected requirements.
Why does MySQL allocate cache and buffer to improve performance?
When a mysqld instance spawns within the host system, MySQL allocates buffers and caches to improve performance of database operations based on the set values set on a specific configuration.
What’s the first rule of MySQL memory usage?
The first rule of configuring MySQL memory usage is you never want your MySQL to cause the operating system to swap. Even minor swapping activity can dramatically reduce MySQL performance. Note the keyword “activity” here.
How often does mysqld need to be restarted?
From database restart up to a total shutdown takes about a week , thus database needs to be restarted about once a week. memory instruments have been enabled to try and find the cause, however nothing was found to be out of the ordinary. using some monitoring commands, it simply states that the mysqld process itself is taking up all the memory.
Why does MySQL keep swapping out memory?
Without this configuration setting, you might find the OS swapping out portions of MySQL just because it feels it needs to increase the amount of available file cache (which is almost always a wrong choice for MySQL). The next thing when it comes to OS configuration is setting the Out Of Memory killer.
What’s the maximum memory for MySQL in CentOS?
I ran the MySQLTuner script, and followed the recommendations that they gave, but it’s still recommending increases, while telling me that MySQL’s maximum memory usage is dangerously high. I have a CentOS 6.5 with 64 GB RAM.
How does MySQL allocate memory for temporary tables?
MySQL also allocates memory for temporary tables unless it becomes too large (determined by tmp_table_size and max_heap_table_size ).
Is it impractical to reserve memory in MySQL?
The MySQL Performance Blog does a good job of covering your question, and lists many reasons why it’s hugely impractical to “reserve” memory. If you really want to impose a hard limit, you could do so, but you’d have to do it at the OS level as there is no built-in setting.
How many important settings are in MySQL Stack Overflow?
Most MySQL tips on stackoverflow will tell you about 5-8 so called important settings. First off, not all of them matter – e.g. allocating a lot of resources to InnoDB and not using InnoDB doesn’t make a lot of sense because those resources are wasted.
Which is the best resource for MySQL tips?
It’s a great resource for all kinds of MySQL-related tips. And it’s not just MySQL, they also know a lot about the right hardware or recommend setups for AWS, etc.. These guys have years and years of experience. Another great resource is planet-mysql, of course.