To ensure the stability and security of clusters, AnalyticDB for MySQL is subject to the limits that are described in the following tables.
Naming limits
Object | Naming convention |
Database name |
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Table name |
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Column name |
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Index name | The name can be up to 64 characters in length. |
Account name |
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Password |
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Quota limits
Limits | Default value | Description |
Maximum number of clusters that can be purchased within each Alibaba Cloud account | 30 | Each Alibaba Cloud account can purchase up to 30 clusters. To change this value, submit a ticket. |
Maximum number of databases that can be created for each cluster | 2048 | None |
Total number of scale-in, scale-out, upgrade, and downgrade operations on each cluster per day | 12 | None |
Maximum disk usage for a Data Warehouse Edition cluster in reserved mode | 80% | If the disk usage of a cluster exceeds the threshold, the system sends an alert notification. Each contact can receive up to four alert notifications for disk usage every day. |
90% | If the disk usage of a cluster exceeds the threshold, the system sends an alert notification, locks the cluster, and denies data write requests. Each contact can receive up to four alert notifications for disk usage every day. | |
Maximum amount of hot data for an elastic I/O unit (EIU) within a Data Warehouse Edition cluster in elastic mode | 8 TB | If the amount of hot data for an EIU exceeds 8 TB, the system locks the cluster and denies data write requests. For information about how to resolve this issue, see Monitoring. |
Maximum amount of hot data for a set of reserved storage resources within a Data Lakehouse Edition cluster | 8 TB | If the amount of hot data for a set of reserved storage resources exceeds 8 TB, the system locks the cluster and denies data write requests. For information about how to resolve this issue, see Monitoring. |
Maximum number of standard accounts that can be created for each cluster | 256 | None |
Maximum number of connections that can be established to each cluster | No more than 50000 (recommended) | The number of connections that can be established to an AnalyticDB for MySQL cluster is not limited but varies based on the cluster specifications. Low-specification clusters cannot support excessive connections due to insufficient resources. |
Maximum number of IP address whitelists that can be configured for each cluster | 50 | None |
Maximum number of IP addresses that can be added to each whitelist | 1000 | None |
Maximum number of IP addresses that can be added to whitelists in each cluster | 25000 | None |
Maximum number of partitions in each cluster | 102400 | None |
Maximum number of tables that can be created for each Data Warehouse Edition cluster in reserved mode that has 1 to 20 node groups |
|
|
Maximum number of internal tables that can be created for each Data Lakehouse Edition cluster or Data Warehouse Edition cluster in elastic mode |
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Maximum number of external tables that can be created for each Data Lakehouse Edition cluster or Data Warehouse Edition cluster in elastic mode | 500000 | None |
Maximum number of columns in each table | 4096 | None |
Maximum length of comments in each table | 1024 characters | None |
Maximum length of comments in each column | 1024 characters | None |
Maximum length of a single field in each column | 16 MB | None |
Maximum length of data that can be written to each row | 16 MB | None |
Default length of each column | 127 characters | None |
Maximum number of columns that can be contained in each query | 1024 | None |
Maximum number of items that can be specified in each WHERE clause | 256 | None |
Maximum number of conditions that can be specified in each IN operator | 2000 | The following SQL statement can be used to modify this value based on your business requirements: SET adb_config MAX_IN_ITEMS_COUNT. Example: A larger value makes an SQL query more complex and may affect query performance. |
Query the number of shards
When you create an AnalyticDB for MySQL cluster, the number of shards is determined. The following tables describe the number of shards corresponding to different specifications.
Data Lakehouse Edition or Data Warehouse Edition in elastic mode
Number of EIUs, sets of reserved resources, or sets of reserved storage resources
Number of shards
0 or 1
64
2‒3
64
4‒7
96
8‒15
256
16‒31
384
32‒63
512
> 64
1024
ImportantFor Data Lakehouse Edition clusters, the number of sets of reserved storage resources can be calculated by using the following formula: Amount of reserved storage resources/24 ACUs.
Data Warehouse Edition in reserved mode
Number of node groups
Number of shards
1
16
2‒3
64
4‒7
96
8‒15
236
16‒31
384
32‒63
512
> 64
1024
You can execute the following statement to query the number of shards in an existing AnalyticDB for MySQL cluster:
SELECT count(1) FROM information_schema.kepler_meta_shards;.
Timeout limits
Operation | Timeout period (ms) | Description |
Create a cluster | 600,000 | None |
Delete a cluster | 300,000 | None |
Scale up a cluster | 600,000 | None |
Create a database | 10,000 | None |
Delete a database | 10,000 | None |
Create a table or view | 10,000 | None |
Delete a table or view | 10,000 | None |
Truncate a table | 60,000 | None |
Add a column | 10,000 | None |
Remove a column | 60,000 | None |
Update a column | 60,000 | None |
Perform a single query | 1,800,000 | The timeout period for a query. When a query times out, the system ends the query. You can modify the timeout period for a query by using the following parameter and hint:
Note The system checks queries for timeout errors every 1,000 milliseconds. The execution duration of a query must be set to a value that is greater than 1,000 milliseconds. Otherwise, the query_timeout hint may not take effect. |
Insert data | 300,000 | None |
| 24 × 3,600,000 | The timeout period for an INSERT statement. When an INSERT statement times out, the system ends the statement. You can modify the timeout period for an INSERT statement by using the following parameter and hint:
|