Before you begin, it's important to know the shape and structure of the event you're trying to query, especially if this is your first time using this feature.
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Start by exiting the playground back to the default query view, and creating a new query called 'Last N events' (or whatever you like, really), by clicking the + button.
Next, copy the code above into the Params section. This will be the body of your query, and all your logic should go in here.
This is an aggregate query, which should be selected from the Type drop down menu. This will place a wrapper around the query when it's ran. A find option is available also, but we won't be using that to begin with here.
Prompting User Input
Note the 'limit' value:
"$limit":"#n#"
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This is a fairly simple query, and probably won't get you too far in terms of displaying graphs.
Our Query Examples and Tips section will go more in to detail on different query types and how to display the data you wish to see.
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