time series

streams of timestamped values belonging to the same metric and the same set of labeled dimensions. 

Metric names and labels

指标名和标签

Every time series is uniquely identified by its metric name and a set of key-value pairs, also known as labels.

It may contain ASCII letters and digits, as well as underscores and colons. 
It must match the regex [a-zA-Z_:][a-zA-Z0-9_:]*
指标名  字母数字 下划线 冒号

The colons are reserved for user defined recording rules. They should not be used by exporters or direct instrumentation.

冒号保留给用户定义的记录规则。不应该被exporter或 direct instrumentation  使用。

direct instrumentation   直接代码打点

Labels enable dimensional data model   维度数据模型
The query language allows filtering and aggregation based on these dimensions. 

基于维度过滤 聚合
Changing any label value, including adding or removing a label, will create a new time series.

Label names may contain ASCII letters, numbers, as well as underscores. 
标签名只能包含 字母 数字和下划线 
Label names beginning with __ are reserved for internal use. 
双下划线开始的标签名只供内部使用

best practices for naming metrics and labels
https://prometheus.io/docs/practices/naming/


Each sample consists of:

a float64 value
a millisecond-precision timestamp

64位浮点数  精度为毫秒的时间戳

metric name + a set of labels

metric-name{label-name=label-value, ...}


api_http_requests_total{method="POST", handler="/messages"}


node_network_receive_bytes_total{device="en0"}

node_network_receive_bytes_total{device="en0"}

node_load1