SHOW CHILD PATHS pathPattern
Return all child paths and their node types of all the paths matching pathPattern.
node types: ROOT -> SG INTERNAL -> STORAGE GROUP -> INTERNAL -> DEVICE -> TIMESERIES
Example:
+------------+----------+ | child paths|node types| +------------+----------+ |root.ln.wf01| INTERNAL| |root.ln.wf02| INTERNAL| +------------+----------+ Total line number = 2 It costs 0.002s
get all paths in form of root.xx.xx.xx:show child paths root.xx.xx
SHOW CHILD NODES pathPattern
Return all child nodes of the pathPattern.
Example:
+------------+ | child nodes| +------------+ | ln| +------------+
+------------+ | child nodes| +------------+ | wf01| | wf02| +------------+
IoTDB is able to use COUNT NODES <PathPattern> LEVEL=<INTEGER>
to count the number of nodes at the given level in current Metadata Tree considering a given pattern. IoTDB will find paths that match the pattern and counts distinct nodes at the specified level among the matched paths. This could be used to query the number of devices with specified measurements. The usage are as follows:
IoTDB > COUNT NODES root.** LEVEL=2 IoTDB > COUNT NODES root.ln.** LEVEL=2 IoTDB > COUNT NODES root.ln.wf01.** LEVEL=3 IoTDB > COUNT NODES root.**.temperature LEVEL=3
As for the above mentioned example and Metadata tree, you can get following results:
+------------+ |count(nodes)| +------------+ | 4| +------------+ Total line number = 1 It costs 0.003s +------------+ |count(nodes)| +------------+ | 2| +------------+ Total line number = 1 It costs 0.002s +------------+ |count(nodes)| +------------+ | 1| +------------+ Total line number = 1 It costs 0.002s +------------+ |count(nodes)| +------------+ | 2| +------------+ Total line number = 1 It costs 0.002s
Note: The path of timeseries is just a filter condition, which has no relationship with the definition of level.
Similar to Show Timeseries
, IoTDB also supports two ways of viewing devices:
SHOW DEVICES
statement presents all devices' information, which is equal to SHOW DEVICES root.**
.SHOW DEVICES <PathPattern>
statement specifies the PathPattern
and returns the devices information matching the pathPattern and under the given level.SQL statement is as follows:
IoTDB> show devices IoTDB> show devices root.ln.**
You can get results below:
+-------------------+---------+ | devices|isAligned| +-------------------+---------+ | root.ln.wf01.wt01| false| | root.ln.wf02.wt02| false| |root.sgcc.wf03.wt01| false| | root.turbine.d1| false| +-------------------+---------+ Total line number = 4 It costs 0.002s +-----------------+---------+ | devices|isAligned| +-----------------+---------+ |root.ln.wf01.wt01| false| |root.ln.wf02.wt02| false| +-----------------+---------+ Total line number = 2 It costs 0.001s
isAligned
indicates whether the timeseries under the device are aligned.
To view devices' information with storage group, we can use SHOW DEVICES WITH STORAGE GROUP
statement.
SHOW DEVICES WITH STORAGE GROUP
statement presents all devices' information with their storage group.SHOW DEVICES <PathPattern> WITH STORAGE GROUP
statement specifies the PathPattern
and returns the devices' information under the given level with their storage group information.SQL statement is as follows:
IoTDB> show devices with storage group IoTDB> show devices root.ln.** with storage group
You can get results below:
+-------------------+-------------+---------+ | devices|storage group|isAligned| +-------------------+-------------+---------+ | root.ln.wf01.wt01| root.ln| false| | root.ln.wf02.wt02| root.ln| false| |root.sgcc.wf03.wt01| root.sgcc| false| | root.turbine.d1| root.turbine| false| +-------------------+-------------+---------+ Total line number = 4 It costs 0.003s +-----------------+-------------+---------+ | devices|storage group|isAligned| +-----------------+-------------+---------+ |root.ln.wf01.wt01| root.ln| false| |root.ln.wf02.wt02| root.ln| false| +-----------------+-------------+---------+ Total line number = 2 It costs 0.001s
The above statement is used to count the number of devices. At the same time, it is allowed to specify PathPattern
to count the number of devices matching the PathPattern
.
SQL statement is as follows:
IoTDB> show devices IoTDB> count devices IoTDB> count devices root.ln.**
You can get results below:
+-------------------+---------+ | devices|isAligned| +-------------------+---------+ |root.sgcc.wf03.wt03| false| | root.turbine.d1| false| | root.ln.wf02.wt02| false| | root.ln.wf01.wt01| false| +-------------------+---------+ Total line number = 4 It costs 0.024s +--------------+ |count(devices)| +--------------+ | 4| +--------------+ Total line number = 1 It costs 0.004s +--------------+ |count(devices)| +--------------+ | 2| +--------------+ Total line number = 1 It costs 0.004s