Document required order for time series queries (#13204)

docs/sources/features/datasources/mssql.md

@@ -174,6 +174,8 @@ The resulting table panel:
 If you set `Format as` to `Time series`, for use in Graph panel for example, then the query must must have a column named `time` that returns either a sql datetime or any numeric datatype representing unix epoch in seconds. You may return a column named `metric` that is used as metric name for the value column. Any column except `time` and `metric` is treated as a value column. If you omit the `metric` column, the name of the value column will be the metric name. You may select multiple value columns, each will have its name as metric.
 If you return multiple value columns and a column named `metric` then this column is used as prefix for the series name (only available in Grafana 5.3+).
 
+Resultsets of time series queries need to be sorted by time.
+
 **Example database table:**
 
 ```sql

docs/sources/features/datasources/mysql.md

@@ -129,6 +129,8 @@ Any column except `time` and `metric` is treated as a value column.
 You may return a column named `metric` that is used as metric name for the value column.
 If you return multiple value columns and a column named `metric` then this column is used as prefix for the series name (only available in Grafana 5.3+).
 
+Resultsets of time series queries need to be sorted by time.
+
 **Example with `metric` column:**
 
 ```sql

docs/sources/features/datasources/postgres.md

@@ -129,6 +129,8 @@ Any column except `time` and `metric` is treated as a value column.
 You may return a column named `metric` that is used as metric name for the value column.
 If you return multiple value columns and a column named `metric` then this column is used as prefix for the series name (only available in Grafana 5.3+).
 
+Resultsets of time series queries need to be sorted by time.
+
 **Example with `metric` column:**
 
 ```sql

public/app/plugins/datasource/mssql/partials/query.editor.html

@@ -45,6 +45,8 @@ Optional:
   - If multiple value columns are returned the metric column is used as prefix.
   - If no column named metric is found the column name of the value column is used as series name
 
+Resultsets of time series queries need to be sorted by time.
+
 Table:
 - return any set of columns
 

public/app/plugins/datasource/mysql/partials/query.editor.html

@@ -45,6 +45,8 @@ Optional:
   - If multiple value columns are returned the metric column is used as prefix.
   - If no column named metric is found the column name of the value column is used as series name
 
+Resultsets of time series queries need to be sorted by time.
+
 Table:
 - return any set of columns
 

public/app/plugins/datasource/postgres/partials/query.editor.html

@@ -143,6 +143,8 @@ Optional:
   - If multiple value columns are returned the metric column is used as prefix. 
   - If no column named metric is found the column name of the value column is used as series name
 
+Resultsets of time series queries need to be sorted by time.
+
 Table:
 - return any set of columns