How does the buffer pool work in SQL Server?
In order to understand how the Buffer Pool works and how it benefits our query processing we need to see it in action. Fortunately SQL Server gives us several management views and built in functionality to see exactly how the Buffer Pool is being used and how, or more importantly if, our queries are utilising it efficiently.
Where do I find page descriptors in buffer pool?
Prior to SQL 2005, there was no easy way to find information about pages in buffer pool. From SQL Server 2005 onwards, each data page in buffer pool has one buffer descriptor. Buffer descriptors DMV can uniquely identify each data page that is currently cached in an instance of SQL Server under buffer pool.
Can a cold cache fetch pages from the buffer pool?
We can see that from a cold cache our query of 10000 rows has quite naturally needed to fetch pages into the Buffer Pool via disk during execution but the key point is that the subsequent executions of the query have not used disk but have reused the stored pages.
How does the buffer descriptor work in SQL Server?
Buffer descriptors DMV can uniquely identify each data page that is currently cached in an instance of SQL Server under buffer pool. This DMV sys.dm_os_buffer_descriptors returns cached pages for all user and system databases.
How big should be MySQL’s buffer pool size?
The database runs on a Debian server using SSD disks and I’ve set max connections = 800 which sometimes saturate and grind the server to halt. The average query per second is about 2.5K.
How big is the buffer pool in InnoDB?
Your innodb_buffer_pool_size is enormous. You have it set at 20971520000. That’s 19.5135 GB. If you only have 5GB of InnoDB data and indexes, then you should only have about 8GB.
How long does it take to initialize a buffer pool?
The time to initialize the buffer pool is roughly proportional to its size. On large installations, this initialization time may be significant. For example, on a modern Linux x86_64 server, initialization of a 10GB buffer pool takes approximately 6 seconds. See Section 8.9.1, “The InnoDB Buffer Pool”.