This topic describes the limits of PolarDB for MySQL.
Limits
Edition | Node type CPU and memory | Maximum memory for the file system | Maximum number of files | Maximum number of connections |
Cluster Edition (Dedicated) | polar.mysql.x4.medium 2 cores, 8 GB | 800 MB | 1,024,000 | 6,000 |
polar.mysql.x4.large 4 cores, 16 GB | 1,300 MB | 2,048,000 | 8,000 | |
polar.mysql.x4.xlarge 8 cores, 32 GB | 2,400 MB | 4,096,000 | 10,000 | |
polar.mysql.x8.xlarge 8 cores, 64 GB | 3,500 MB | 6,144,000 | 16,000 | |
polar.mysql.x8.2xlarge 16 cores, 128 GB | 10,240 MB | 20,480,000 | 32,000 | |
polar.mysql.x8.4xlarge 32 cores, 256 GB | 10,240 MB | 20,480,000 | 64,000 | |
polar.mysql.x8.8xlarge 64 cores, 512 GB | 10,240 MB | 20,480,000 | 64,000 | |
polar.mysql.x8.12xlarge 88 cores, 710 GB | 10,240 MB | 20,480,000 | 100,000 | |
Cluster Edition (General-purpose) | polar.mysql.g2.medium 2 cores, 4 GB | 800 MB | 1,024,000 | 1,800 |
polar.mysql.g4.medium 2 cores, 8 GB | 800 MB | 1,024,000 | 2,000 | |
polar.mysql.g2.large 4 cores, 8 GB | 1,300 MB | 2,048,000 | 3,000 | |
polar.mysql.g4.large 4 cores, 16 GB | 1,300 MB | 2,048,000 | 6,000 | |
polar.mysql.g2.xlarge 8 cores, 16 GB | 1,300 MB | 2,048,000 | 6,000 | |
polar.mysql.g4.xlarge 8 cores, 32 GB | 2,400 MB | 4,096,000 | 10,000 | |
polar.mysql.g4.2xlarge 16 cores, 64 GB | 3,500 MB | 6,144,000 | 16,000 | |
polar.mysql.g4.4xlarge 32 cores, 128 GB | 10,240 MB | 20,480,000 | 32,000 |
The preceding table describes the limits of PolarDB for MySQL on the following metrics:
Maximum memory for the file system
This metric refers to the amount of memory that can be consumed by the file system when the upper limit of the storage for a cluster is reached. In this case, the cluster handles read and write requests as normal (unless stress testing or DDL operations on large tables are involved). If the upper limit of the cluster's storage is not reached, the amount of consumed memory is within this limit.
Maximum number of files
User files, database system files (about 100 files), and log files are included. To view the number of log files, run the
SHOW POLAR LOGScommand. A non-partitioned PolarDB table occupies two files, while a partitioned table occupiesN + 2files (N represents the number of partitions). The following error message appears when you create a table after the maximum number of files is reached:ERROR 3017 (HY000): Too many files. PolarDB only supports 2048 files every 10GB disk size. Please drop some tables/databases before creating new tablesIn this case, you need to delete some tables or scale your cluster.
Maximum connections
In the preceding table, the number of connections refers to the number of connections for an individual node, not for a cluster.
Other limits
Item | Description of the limit |
Table name | The name of a table in a cluster can be up to 64 letters and digits or 50 Chinese characters in length. |
Serializable isolation level | Not supported. |
FAQ
Can I create 10,000 databases in PolarDB? What is the maximum number of databases in a cluster?
Yes, you can create 10,000 databases in PolarDB. PolarDB does not limit the number of databases in a cluster. However, the number of databases may be constrained by the specifications of the cluster and the corresponding maximum number of files.
How much data can a table store in PolarDB for MySQL?
A table can store up to 64 TB of data.
Is the maximum number of connections related with the number of read-only nodes? Can I increase the maximum number of connections by adding read-only nodes?
No, the maximum number of connections is not related with the number of read-only nodes. It is determined by the node specifications. To increase the limit, you need to scale up the cluster. For more information, see Manually upgrade or downgrade a PolarDB cluster.