What a time series is
A time series is an ordered sequence of points, each a pair of a timestamp and a numeric value. Time series databases are built around the fact that data arrives in time order and is almost always queried by time range.
Identifying a series
A single series is identified by a metric name plus a set of labels (key value pairs). Together they form a unique identity. For example a metric named http requests total with labels for method and status code is one series, while a different status code is a different series.
Why this shape matters
- Points for one series are append only and roughly sorted by time, which enables tight compression.
- Queries select series by name and labels, then scan a time window.
- The value is usually a float, sometimes an integer counter.
The cardinality consequence
Every unique combination of labels creates a new series. This makes the model expressive but also dangerous, since careless labels multiply series count.
Key idea
A metric is not one number but a family of series, each pinned by a name and labels, storing ordered timestamp value points.