LindormTSDB organizes time series data into databases. Each database isolates its data from other databases and holds one or more time series tables. Use databases to separate data from different projects on the same instance, and control access on a per-database basis.
How databases work
Each LindormTSDB instance manages one or more databases. Data is isolated between databases, so writing data from unrelated projects to the same instance keeps each project's data logically separate. To enforce access control, store each project's data in a dedicated database and grant permissions on a per-database basis.
The following figure shows the LindormTSDB data layers based on the concepts described in Data models.
Users with the required permissions can also access data across databases.
Database-level data management
LindormTSDB provides two database-level settings for managing the lifecycle of time series data:
| Setting | Description |
|---|---|
| Cold/hot data boundary | Separates cold data from hot data within a database. For details, see Cold data archiving. |
| Time to live (TTL) | Defines how long data is retained. When the time between a data record's timestamp and the current time exceeds the TTL, LindormTSDB considers the data expired and clears it. |
Both settings are evaluated against event time — the point in time when the event corresponding to the data occurred — not ingestion time (the time the data was written to the database).
Keep the following behaviors in mind when configuring these settings:
LindormTSDB uses asynchronous compaction tasks to archive cold data and clear expired data. As a result, archival and deletion are not immediate and may be delayed.
If both a cold/hot data boundary and a TTL are configured, LindormTSDB triggers a task to clear archived cold data when that cold data expires.
If you write data whose timestamp already exceeds the TTL, the write succeeds, but the data cannot be retrieved in subsequent queries.
Manage databases with SQL
LindormTSDB supports the following SQL operations on databases:
| Operation | SQL statement | Description |
|---|---|---|
| Create a database | CREATE DATABASE | Creates a new database. For full syntax, see CREATE DATABASE. |
| Delete a database | DROP DATABASE | Permanently deletes a database. For full syntax, see DROP DATABASE. |
| Modify database attributes | ALTER DATABASE | Changes database attributes such as the cold/hot data boundary and TTL. For full syntax, see ALTER DATABASE. |
| Query database attributes | DESCRIBE DATABASE | Returns the current attributes of a database. For full syntax, see DESCRIBE DATABASE. |
By default, a newly created database has no access permissions granted. Grant the required permissions before performing operations on it.
Manage databases in the Lindorm console
In the Lindorm console, use the Database Management tab to configure the cold/hot data boundary and data retention policy for a database.
The Lindorm console does not support creating or deleting databases. Use the CREATE DATABASE and DROP DATABASE SQL statements for these operations.