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OpenTSDB Line Protocol


A single line of text is used in OpenTSDB line protocol to represent one row of data. OpenTSDB employs a single column data model, so each line can only contain a single data column. There can be multiple tags. Each line contains 4 parts as below:

<metric> <timestamp> <value> <tagk_1>=<tagv_1>[ <tagk_n>=<tagv_n>]
  • metric will be used as the STable name.
  • timestamp is the timestamp of current row of data. The time precision will be determined automatically based on the length of the timestamp. Second and millisecond time precision are supported.
  • value is a metric which must be a numeric value, The corresponding column name is "value".
  • The last part is the tag set separated by spaces, all tags will be converted to NCHAR type automatically.

For example:

meters.current 1648432611250 11.3 location=California.LosAngeles groupid=3
  • The rule of table name

    • The child table name is created automatically in a rule to guarantee its uniqueness.
    • You can configure smlAutoChildTableNameDelimiter in taos.cfg to specify a delimiter between tag values as the table names. For example, you set smlAutoChildTableNameDelimiter=- in taos.cfg, when you insert st,t0=cpu1,t1=4 c1=3 1626006833639000000, the child table will be cpu1-4
    • You can configure smlChildTableName in taos.cfg to specify a tag value as the table names if the tag value is unique globally. For example, if a tag is called tname and you set smlChildTableName=tname in taos.cfg, when you insert st,tname=cpu1,t1=4 c1=3 1626006833639000000, the child table cpu1 will be created automatically. Note that if multiple rows have the same tname but different tag_set values, the tag_set of the first row is used to create the table and the others are ignored

    Please refer to OpenTSDB Telnet API for more details.


package com.taos.example;

import com.taosdata.jdbc.SchemalessWriter;
import com.taosdata.jdbc.enums.SchemalessProtocolType;
import com.taosdata.jdbc.enums.SchemalessTimestampType;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

public class TelnetLineProtocolExample {
// format: <metric> <timestamp> <value> <tagk_1>=<tagv_1>[ <tagk_n>=<tagv_n>]
private static String[] lines = { "meters.current 1648432611249 10.3 location=California.SanFrancisco groupid=2",
"meters.current 1648432611250 12.6 location=California.SanFrancisco groupid=2",
"meters.current 1648432611249 10.8 location=California.LosAngeles groupid=3",
"meters.current 1648432611250 11.3 location=California.LosAngeles groupid=3",
"meters.voltage 1648432611249 219 location=California.SanFrancisco groupid=2",
"meters.voltage 1648432611250 218 location=California.SanFrancisco groupid=2",
"meters.voltage 1648432611249 221 location=California.LosAngeles groupid=3",
"meters.voltage 1648432611250 217 location=California.LosAngeles groupid=3",

private static Connection getConnection() throws SQLException {
String jdbcUrl = "jdbc:TAOS://localhost:6030?user=root&password=taosdata";
return DriverManager.getConnection(jdbcUrl);

private static void createDatabase(Connection conn) throws SQLException {
try (Statement stmt = conn.createStatement()) {
// the default precision is ms (microsecond), but we use us(microsecond) here.
stmt.execute("CREATE DATABASE IF NOT EXISTS test precision 'us'");
stmt.execute("USE test");

public static void main(String[] args) throws SQLException {
try (Connection conn = getConnection()) {
SchemalessWriter writer = new SchemalessWriter(conn);
writer.write(lines, SchemalessProtocolType.TELNET, SchemalessTimestampType.NOT_CONFIGURED);


view source code

2 STables will be created automatically and each STable has 4 rows of data in the above sample code.

taos> use test;
Database changed.

taos> show stables;
name |
meters_current |
meters_voltage |
Query OK, 2 row(s) in set (0.002544s)

taos> select tbname, * from `meters_current`;
tbname | _ts | _value | groupid | location |
t_0e7bcfa21a02331c06764f275... | 2022-03-28 09:56:51.249 | 10.800000000 | 3 | California.LosAngeles |
t_0e7bcfa21a02331c06764f275... | 2022-03-28 09:56:51.250 | 11.300000000 | 3 | California.LosAngeles |
t_7e7b26dd860280242c6492a16... | 2022-03-28 09:56:51.249 | 10.300000000 | 2 | California.SanFrancisco |
t_7e7b26dd860280242c6492a16... | 2022-03-28 09:56:51.250 | 12.600000000 | 2 | California.SanFrancisco |
Query OK, 4 row(s) in set (0.005399s)

Query Examples

If you want query the data of location=California.LosAngeles groupid=3, here is the query SQL:

SELECT * FROM `meters_current` WHERE location = "California.LosAngeles" AND groupid = 3;