The Time Series Database (TSDB) SQL query engine supports SQL-like queries and time series data queries. The engine allows you to use TSQL to query multiple metrics based on JOIN operations. The TSDB SQL query engine is also known as the TSQL query engine or the TSQL engine.
This topic describes the relationship between time series data and relational data and the time series data models that are based on SQL relational models.
The following diagram shows a time series in a TSDB database. For information about metrics, tags, tag values, timestamps, and values in TSDB, see Terms.
An SQL relational model is a two-dimensional relational table. The preceding time series data can be organized into the following two-dimensional table.
Table:Temperature | ||||
|---|---|---|---|---|
timestamp | value | Floor | Room | DeviceID |
1492158910 | 26 | 33 | 3302 | 7649501 |
1492158920 | 25.8 | 33 | 3302 | 7649501 |
1492158930 | 26.1 | 33 | 3302 | 7649501 |
1492158940 | 26.3 | 33 | 3302 | 7649501 |
1492158950 | 26.5 | 33 | 3302 | 7649501 |
... |
Mapping between a time series data model and a relational model
TSDB time series data model | TSDB SQL relational model |
|---|---|
Metric | Table. |
Timestamp | The timestamp column in a table. The data type of the values in this column is TIMESTAMP. |
Value | The value column in a table. The supported data types of the metric values in this column are DOUBLE, VARCHAR, and BOOLEAN. The multi-value model is not supported, and the values of multiple fields cannot be returned for single table queries. |
Tag key | The TagKey column in a table. The data type of the values in this column is VARCHAR. |
Tag value | Each value in the TagKey column. |