Frequently Asked Questions

Outline

• Frequently Asked Questions
  • How can I identify my version of IoTDB?
  • Where can I find IoTDB logs?
  • Where can I find IoTDB data files?
  • How do I know how many time series are stored in IoTDB?
  • Can I use Hadoop and Spark to read TsFile in IoTDB?
  • How does IoTDB handle duplicate points?
  • How can I tell what type of the specific timeseries?
  • How can I change IoTDB’s Cli time display format?

How can I identify my version of IoTDB?

There are several ways to identify the version of IoTDB that you are using:

• Launch IoTDB’s Command Line Interface:

> ./start-cli.sh -p 6667 -pw root -u root -h localhost
 _____       _________  ______   ______    
|_   _|     |  _   _  ||_   _ `.|_   _ \   
  | |   .--.|_/ | | \_|  | | `. \ | |_) |  
  | | / .'`\ \  | |      | |  | | |  __'.  
 _| |_| \__. | _| |_    _| |_.' /_| |__) | 
|_____|'.__.' |_____|  |______.'|_______/  version x.x.x

• Check pom.xml file:

<version>x.x.x</version>

• Use JDBC API:

String iotdbVersion = tsfileDatabaseMetadata.getDatabaseProductVersion();

• Use Command Line Interface:

IoTDB> show version
show version
+---------------+
|version        |
+---------------+
|x.x.x          |
+---------------+
Total line number = 1
It costs 0.241s

Where can I find IoTDB logs?

Suppose your root directory is:

$ pwd
/workspace/iotdb
$ ls -l
server/
cli/
pom.xml
Readme.md
...

Let $IOTDB_HOME = /workspace/iotdb/server/target/iotdb-server-{project.version}

Let $IOTDB_CLI_HOME = /workspace/iotdb/cli/target/iotdb-cli-{project.version}

By default settings, the logs are stored under IOTDB_HOME/logs. You can change log level and storage path by configuring logback.xml under IOTDB_HOME/conf.

Where can I find IoTDB data files?

By default settings, the data files (including tsfile, metadata, and WAL files) are stored under IOTDB_HOME/data.

How do I know how many time series are stored in IoTDB?

Use IoTDB’s Command Line Interface:

IoTDB> show timeseries root

In the result, there is a statement shows Total timeseries number, this number is the timeseries number in IoTDB.

In the current version, IoTDB supports querying the number of time series. Use IoTDB’s Command Line Interface:

IoTDB> count timeseries root

If you are using Linux, you can use the following shell command:

> grep "0,root" $IOTDB_HOME/data/system/schema/mlog.txt |  wc -l
>   6

Can I use Hadoop and Spark to read TsFile in IoTDB?

Yes. IoTDB has intense integration with Open Source Ecosystem. IoTDB supports Hadoop (opens new window), Spark (opens new window) and Grafana (opens new window) visualization tool.

How does IoTDB handle duplicate points?

A data point is uniquely identified by a full time series path (e.g. root.vehicle.d0.s0) and timestamp. If you submit a new point with the same path and timestamp as an existing point, IoTDB updates the value of this point instead of inserting a new point.

How can I tell what type of the specific timeseries?

Use SHOW TIMESERIES <timeseries path> SQL in IoTDB’s Command Line Interface:

For example, if you want to know the type of all timeseries, the <timeseries path> should be root. The statement will be:

IoTDB> show timeseries root

If you want to query specific sensor, you can replace the <timeseries path> with the sensor name. For example:

IoTDB> show timeseries root.fit.d1.s1

Otherwise, you can also use wildcard in timeseries path:

IoTDB> show timeseries root.fit.d1.*

How can I change IoTDB’s Cli time display format?

The default IoTDB’s Cli time display format is readable (e.g. 1970-01-01T08:00:00.001), if you want to display time in timestamp type or other readable format, add parameter -disableISO8601 in start command:

> $IOTDB_CLI_HOME/sbin/start-cli.sh -h 127.0.0.1 -p 6667 -u root -pw root -disableISO8601