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Use Cases of Custom Commands
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Last updated: 2024-11-05 10:22:22
Use Cases of Custom Commands
Last updated: 2024-11-05 10:22:22
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Through VIP encapsulation, Memory Edition (Cluster Architecture) delivers a user experience in cluster mode comparable to the standalone edition, making it much easier for use in different scenarios. However, in Ops scenarios, each node in the cluster needs to be accessed frequently to locate exceptions. In this case, the custom command feature can add a node ID parameter to the parameter list of the original command in the format of COMMAND arg1 arg2 ... [node ID] in order to easily get the information of the specified node. The node ID can be obtained from the Node Management page in the TencentDB for Redis® console or through the cluster nodes command.

Version Description

On proxy agent versions prior to v5.5.0, the node ID is required for the execution of custom commands, but it is unnecessary on v5.5.0 and later.

INFO

This command returns the information and statistics of a server.

Custom command format

info [section] [node ID]
Here, optional parameters can be used to select a specific part of the information:
server: The general information of a Redis server.
clients: The information of connected clients.
memory: The information of memory usage.
persistence: The information of RDB and AOF.
stats: The general statistics.
replication: The information of master/replica replication.
cpu: The information of CPU usage.
commandstats: The statistics of Redis commands.
cluster: The information of a Redis cluster.
keyspace: statistics of database
Optional parameters can also take the following values:
all: Returns all the information.
default: Returns the default information.
For more information, see INFO Command.

Sample code

The following example runs the INFO command with section being server:


SLOWLOG

This command reads slow logs. It uses SLOWLOG GET to return the entries in slow logs. You can specify to return only the last N entries and pass other parameters to this command, such as SLOWLOG GET 10.

Custom command format

slowlog get [Redis node ID]
slowlog get [slow log quantity][Redis node ID]

Sample code



FLUSHDB

This command deletes all keys of the currently selected database. It will never fail.

Custom command format

flushdb [Redis node ID]

Sample code

cd-crs-rhxxxay.sql.tencentcdb.com:24894> flushdb f2f3c387b9fab0e67af02039845c60278b13bed0
OK

PING

This command is often used to test whether the connection still exists or to measure the latency.

Custom command format

ping [message] [node ID]

Sample code

[ crs-rh**** | DB0 ] # PING "PONG" f2f3c3************************
PONG
[ crs-rh**** | DB0 ] # PING "hello world"
hello world

KEYS

This command queries all the matched keys.

Custom command format

 keys [pattern]  [Redis node ID]

Sample code

keys a* f2f3c3*************************


SCAN

Custom command format

scan cursor [MATCH pattern] [COUNT count] [Redis node ID]

Sample code

[ crs-******** | DB0 ] # scan 0 f2f3c3*************************
1)  "2"

IMonitor

Note：
The iMonitor command requires the Redis proxy version of 5.6.0 or later.
Native Redis does not support the iMonitor command, and redis-cli cannot recognize this command. To execute this command, you should use the telnet tool.
The command needs to be executed on the proxy node, and the parameter is the ID of the Redis shard node.
imonitor [Redis node ID]
Use Cases
imonitor 3dba154c67925520ef1a1e2c41d8cc22d7f4****
+OK
+1680504260.729707 [0 127.0.0.1:6379] "auth" ******
+1680504260.730070 [0 127.0.0.1:6379] "info" "commandstats"
+1680504262.243004 [0 127.0.0.1:6379] "AUTH" ******
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