TDengine provides the functionality of deleting data from a table or STable according to specified time range, it can be used to cleanup abnormal data generated due to device failure. Please be noted that this functionality is only available in Enterprise version, please refer to [TDengine Enterprise Edition](https://tdengine.com/products#enterprise-edition-link)
**Syntax:**
```sql
DELETE FROM [ db_name. ] tb_name [WHERE condition];
```
**Description:** Delete data from a table or STable
**Parameters:**
- `db_name`: Optional parameter, specifies the database in which the table exists; if not specified, the current database will be used.
- `tb_name`: Mandatory parameter, specifies the table name from which data will be deleted, it can be normal table, subtable or STable.
- `condition`: Optional parameter, specifies the data filter condition. If no condition is specified all data will be deleted, so please be cautions to delete data without any condition. The condition used here is only applicable to the first column, i.e. the timestamp column. If the table is a STable, the condition is also applicable to tag columns.
**More Explanations:**
The data can't be recovered once deleted, so please be cautious to use the functionality of deleting data. It's better to firstly make sure the data to be deleted using `select` then execute `delete`.
**Example:**
`meters` is a STable, in which `groupid` is a tag column of int type. Now we want to delete the data older than 2021-10-01 10:40:00.100 and `groupid` is 1. The SQL for this purpose is like below:
```sql
delete from meters where ts < '2021-10-01 10:40:00.100' and groupid=1 ;
```
The output is:
```
Deleted 102000 row(s) from 1020 table(s) (0.421950s)
```
It means totally 102,000 rows of data have been deleted from 1,020 sub tables.
TDengine can be quickly integrated with the open-source data visualization system [Grafana](https://www.grafana.com/) to build a data monitoring and alerting system. The whole process does not require any code development. And you can visualize the contents of the data tables in TDengine on a dashboard.
You can learn more about using the TDengine plugin on [GitHub](https://github.com/taosdata/grafanaplugin/blob/master/README.md).
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@@ -14,12 +17,44 @@ In order for Grafana to add the TDengine data source successfully, the following
1. The TDengine cluster is deployed and functioning properly
2. taosAdapter is installed and running properly. Please refer to the taosAdapter manual for details.
Record these values:
- TDengine REST API url: `http://tdengine.local:6041`.
- TDengine cluster authorization, with user + password.
## Installing Grafana
TDengine currently supports Grafana versions 7.0 and above. Users can go to the Grafana official website to download the installation package and execute the installation according to the current operating system. The download address is as follows: <https://grafana.com/grafana/download>.
TDengine currently supports Grafana versions 7.5 and above. Users can go to the Grafana official website to download the installation package and execute the installation according to the current operating system. The download address is as follows: <https://grafana.com/grafana/download>.
## Configuring Grafana
### Install Grafana Plugin and Configure Data Source
<Tabs defaultValue="script">
<TabItem value="script" label="Using Script">
Set the url and authorization environment variables by `export` or a [`.env`(dotenv) file](https://hexdocs.pm/dotenvy/dotenv-file-format.html):
With this script, TDengine data source plugin and the Grafana data source will be installed and created automatically with Grafana provisioning configurations.
And then, restart Grafana service and open Grafana in web-browser, usually <http://localhost:3000>.
Follow the installation steps in [Grafana](https://grafana.com/grafana/plugins/tdengine-datasource/?tab=installation) with the [``grafana-cli`` command-line tool](https://grafana.com/docs/grafana/latest/administration/cli/) for plugin installation.
```bash
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@@ -50,11 +85,7 @@ If Grafana is running in a Docker environment, the TDengine plugin can be automa
GF_INSTALL_PLUGINS=tdengine-datasource
```
## Using Grafana
### Configuring Data Sources
Users can log in to the Grafana server (username/password: admin/admin) directly through the URL `http://localhost:3000` and add a datasource through `Configuration -> Data Sources` on the left side, as shown in the following figure.
Now users can log in to the Grafana server (username/password: admin/admin) directly through the URL `http://localhost:3000` and add a datasource through `Configuration -> Data Sources` on the left side, as shown in the following figure.
Go back to the main interface to create a dashboard and click Add Query to enter the panel query page:
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@@ -94,4 +128,11 @@ Follow the default prompt to query the average system memory usage for the speci
### Importing the Dashboard
In version 2.3.3.0 and above, you can import the TDinsight Dashboard (Grafana Dashboard ID: [15168](https://grafana.com/grafana/dashboards/15167)) as a monitoring visualization tool for TDengine clusters. You can find installation and usage instructions in the TDinsight User Manual (/reference/tdinsight/).
You can install TDinsight dashboard in data source configuration page (like `http://localhost:3000/datasources/edit/1/dashboards`) as a monitoring visualization tool for TDengine cluster. The dashboard is published in Grafana as [Dashboard 15167 - TDinsight](https://grafana.com/grafana/dashboards/15167). Check the [TDinsight User Manual](/reference/tdinsight/) for the details.
For more dashboards using TDengine data source, [search here in Grafana](https://grafana.com/grafana/dashboards/?dataSource=tdengine-datasource). Here is a sub list:
