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OpenTSDB JSON Protocol

Introduction

A JSON string is used in OpenTSDB JSON to represent one or more rows of data, for example:

[
{
"metric": "sys.cpu.nice",
"timestamp": 1346846400,
"value": 18,
"tags": {
"host": "web01",
"dc": "lga"
}
},
{
"metric": "sys.cpu.nice",
"timestamp": 1346846400,
"value": 9,
"tags": {
"host": "web02",
"dc": "lga"
}
}
]

Similar to OpenTSDB line protocol, metric will be used as the STable name, timestamp is the timestamp to be used, value represents the metric collected, tags are the tag sets.

Please refer to OpenTSDB HTTP API for more details.

note
  • In JSON protocol, strings will be converted to nchar type and numeric values will be converted to double type.
  • Only data in array format is accepted and so an array must be used even if there is only one row.

Examples

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 JSONProtocolExample {
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()) {
stmt.execute("CREATE DATABASE IF NOT EXISTS test");
stmt.execute("USE test");
}
}

private static String getJSONData() {
return "[{\"metric\": \"meters.current\", \"timestamp\": 1648432611249, \"value\": 10.3, \"tags\": {\"location\": \"California.SanFrancisco\", \"groupid\": 2}}," +
" {\"metric\": \"meters.voltage\", \"timestamp\": 1648432611249, \"value\": 219, \"tags\": {\"location\": \"California.LosAngeles\", \"groupid\": 1}}, " +
"{\"metric\": \"meters.current\", \"timestamp\": 1648432611250, \"value\": 12.6, \"tags\": {\"location\": \"California.SanFrancisco\", \"groupid\": 2}}," +
" {\"metric\": \"meters.voltage\", \"timestamp\": 1648432611250, \"value\": 221, \"tags\": {\"location\": \"California.LosAngeles\", \"groupid\": 1}}]";
}

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

view source code

The above sample code will created 2 STables automatically while each STable has 2 rows of data.

taos> use test;
Database changed.

taos> show STables;
name | created_time | columns | tags | tables |
============================================================================================
meters.current | 2022-03-29 16:05:25.193 | 2 | 2 | 1 |
meters.voltage | 2022-03-29 16:05:25.200 | 2 | 2 | 1 |
Query OK, 2 row(s) in set (0.001954s)

taos> select * from `meters.current`;
ts | value | groupid | location |
===================================================================================================================
2022-03-28 09:56:51.249 | 10.300000000 | 2.000000000 | California.SanFrancisco |
2022-03-28 09:56:51.250 | 12.600000000 | 2.000000000 | California.SanFrancisco |
Query OK, 2 row(s) in set (0.004076s)