Check the node load: for the cluster architecture, check the node load. If the QPS of only one or a few nodes exceeds the alarm threshold, there may be a hot key; if the QPS of most nodes is high, the overall load of the TencentDB for Redis instance is high, in which case the instance configuration needs to be upgraded.
Check slow queries: you can check whether there are slow queries in the console, and if so and the slow queries match the time when the problem occurred, the problem may be caused by a big key.
Check the CPU utilization: you can check whether the CPU utilization is too high, and if so, the machine resources may be insufficient, in which case the instance configuration needs to be upgraded.
If your business requires optimization, you can optimize it in terms of hot keys and big keys. If the instance configuration requires upgrade, you can enable read/write separation and add more shards to meet your current business needs.
Troubleshooting the Issue
Optimizing your business
1. Log in to the TencentDB for Redis console and click an instance ID in the instance list to enter the instance management page.
2. On the System Monitoring tab, check whether QPS is high or whether there are unexpected hot keys.
3. After troubleshooting abnormal access, optimize your business logic:
Hot keys: You can split hot keys of complex data structures into several new keys and distribute them across Redis nodes to reduce the pressure. For example, if a two-level hash hot key has a lot of hash elements, you can split it.
Big keys: If the value is too large, you can split the object into multiple key-values so that multiple Redis nodes will share the pressure. If there are too many keys, you can store multiple keys in a hash structure.
Confirm that your business allows inconsistent data before enabling read/write separation, because after it is enabled, inconsistent data may be read from the replica node and the master node (the replica node lags behind the master node). For more information, see Changing Instance Specification.
1. Log in to the TencentDB for Redis console, find the target instance in the instance list, and select Configure > Add Replica in the Operation column.
2. In the pop-up window, adjust the configuration and click OK.
3. Return to the instance list. After the instance becomes Running in the status , you can use it normally.
Heavy write load
Cluster Architecture
Log in to the TencentDB for Redis console, find the target instance in the instance list, and select Configure > Add Shard in the Operation column.
Note
After the configuration is adjusted, the instance will be charged at the price of the new configuration.
When shards are added, the system will automatically balance the slot configuration and migrate data, which may fail in rare cases. We recommend that you perform such operations during off-peak hours to avoid the impact of migration on business access.
Add shards as needed: Each shard supports a QPS of 80,000 to 100,000.
Standard Architecture
Upgrade the instance from standard architecture to cluster architecture to improve the processing power of CPU. Before the upgrade, you need to check the compatibility. For more information, see Check on Migration from Standard Architecture to Cluster Architecture.
1. Log in to the TencentDB for Redis console and click an instance ID in the instance list to enter the instance details page.
2. In the Specs Info section, click Upgrade Architecture.
3. After the upgrade is completed, go to the instance list and select Configure > Add Shard in the Operation column.
Note
If the problem persists, contact us for assistance.
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