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:
  1. > ./start-cli.sh -p 6667 -pw root -u root -h localhost
  2. _____ _________ ______ ______
  3. |_ _| | _ _ ||_ _ `.|_ _ \
  4. | | .--.|_/ | | \_| | | `. \ | |_) |
  5. | | / .'`\ \ | | | | | | | __'.
  6. _| |_| \__. | _| |_ _| |_.' /_| |__) |
  7. |_____|'.__.' |_____| |______.'|_______/ version x.x.x
  • Check pom.xml file:
  1. <version>x.x.x</version>
  • Use JDBC API:
  1. String iotdbVersion = tsfileDatabaseMetadata.getDatabaseProductVersion();
  • Use Command Line Interface:
  1. IoTDB> show version
  2. show version
  3. +---------------+
  4. |version |
  5. +---------------+
  6. |x.x.x |
  7. +---------------+
  8. Total line number = 1
  9. It costs 0.241s

Where can I find IoTDB logs?

Suppose your root directory is:

  1. $ pwd
  2. /workspace/iotdb
  3. $ ls -l
  4. server/
  5. cli/
  6. pom.xml
  7. Readme.md
  8. ...

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:

  1. 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:

  1. IoTDB> count timeseries root

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

  1. > grep "0,root" $IOTDB_HOME/data/system/schema/mlog.txt | wc -l
  2. > 6

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

Yes. IoTDB has intense integration with Open Source Ecosystem. IoTDB supports HadoopFrequently asked questions - 图1 (opens new window), SparkFrequently asked questions - 图2 (opens new window) and GrafanaFrequently asked questions - 图3 (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:

  1. IoTDB> show timeseries root

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

  1. IoTDB> show timeseries root.fit.d1.s1

Otherwise, you can also use wildcard in timeseries path:

  1. 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:

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