This topic describes how to configure the innodb_buffer_pool_size parameter of an ApsaraDB RDS for MariaDB instance based on your business requirements. This way, you can improve the performance of the instance.
Background information
You can reconfigure the innodb_buffer_pool_size parameter to change the size of the InnoDB buffer pool for an RDS instance. The value of this parameter is calculated by using the following formula:
{DBInstanceClassMemory*X/Y} Example:
{DBInstanceClassMemory*7/10}DBInstanceClassMemory is a system variable, which specifies the memory capacity of the RDS instance.
X is the numerator, and Y is the denominator.
The size of the InnoDB buffer pool must be within the following range: [128 MB, DBInstanceClassMemory × 8/10]. The minimum size is 128 MB, and the maximum size is 80% of the memory capacity that you purchased for the RDS instance.
The default size of the InnoDB buffer pool for an RDS instance is calculated based on the following rules:
If
the purchased memory capacity of the RDS instance that uses cloud disksis less than 16 GB, the default size of the InnoDB buffer pool is calculated by using the following formula:Default size of the InnoDB buffer pool = (Purchased memory capacity of the RDS instance - Reserved memory of the RDS instance) × 0.75.NoteThe reserved memory of the RDS instance is calculated by using the following formula:
MIN{Purchased memory capacity of the RDS instance × 0.65, [(Purchased memory capacity of the RDS instance/16384) + 1] × 2048}If
the purchased memory capacity of the RDS instance that uses cloud disksis greater than or equal to 16 GB, the default size of the InnoDB buffer pool is calculated by using the following formula:Default size of the InnoDB buffer pool = Purchased memory capacity of the RDS instance × 0.75.
The default size of the InnoDB buffer pool is an integer multiple of 128. If the calculated result is not an integer multiple of 128, the result is rounded to the nearest integer that is a multiple of 128. For example, an RDS instance provides 1,024 MB of memory, the calculated result is 268, and the nearest integer that is a multiple of 128 is 256. In this case, the default size of the InnoDB buffer pool for the RDS instance is 256 MB.
The following table provides the default size and maximum size of the InnoDB buffer pool for various memory capacities.
Memory capacity (Unit: MB) | Default buffer pool size (Unit: MB) | Recommended maximum buffer pool size (Unit: MB) |
2,048 | 512 | 512 |
4,096 | 1,536 | 1,536 |
8,192 | 4,608 | 4,608 |
16,384 | 12,288 | 12,288 |
32,768 | 24,576 | 25,600 |
65,536 | 49,152 | 52,224 |
131,072 | 98,304 | 104,448 |
196,608 | 147,456 | 156,672 |
229,376 | 172,032 | 183,296 |
262,144 | 196,608 | 208,896 |
491,520 | 368,640 | 393,216 |
The size of the InnoDB buffer pool must be a multiple of the result that is obtained by using the following formula: Value of the innodb_buffer_pool_chunk_size parameter × Value of the innodb_buffer_pool_instances parameter. If the size of the InnoDB buffer pool is not a multiple of the result that you obtain by using the formula, ApsaraDB RDS changes the size to a multiple of the result. For example, if the result that you obtain by using the formula is 1 GB and you set the innodb_buffer_pool_size parameter to 1.5 GB, ApsaraDB changes the value of the innodb_buffer_pool_size parameter to 2 GB.
Change the size of the InnoDB buffer pool for a single RDS instance
- Go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.
In the left-side navigation pane, click Parameters.
Find the innodb_buffer_pool_size parameter, click the
icon. In the dialog box that appears, enter a new value and click OK. 
Click Apply Changes above the parameter list. In the message that appears, click OK. Then, wait for the RDS instance to restart.