## What is Le in metrics?

More particularly they’re counters which form a cumulative histogram, le stands for less than or equal to. So 26688 requests took less than or equal to 200ms, 27760 requests took less than or equal to 400ms, and there were 28860 requests in total.

**What is Le in Prometheus metrics?**

That is using a Prometheus naming convention to get to the per-bucket time series data. Each bucket in the histogram is described by a label called le . le is the canonical abbreviation for “less than or equal”. Therefore, the value of this label encodes the upper inclusive bound for the corresponding histogram bucket.

### What are the types of metrics in Prometheus?

Prometheus has four primary metric types to query for via PromQL: counters, gauges, histograms, and summaries. These metric types fulfill the needs or requirements for most use cases, and are found in Prometheus’ official client libraries: Go, Java, Ruby, and Python.

**What is histogram in metrics?**

Histograms measure the statistical distribution of a set of values including the min, max, mean, median, standard deviation and quantiles i.e. the 75th percentile, 90th percentile, 95th percentile, 99th percentile and 99.9th percentile allowing us to sample observations for things like response sizes.

#### What is histogram in micrometer?

Percentile histograms: Micrometer accumulates values to an underlying histogram and ships a predetermined set of buckets to the monitoring system. The monitoring system’s query language is responsible for calculating percentiles off of this histogram.

**How many metrics can Prometheus handle?**

Prometheus can handle millions of time series. However, with the above mentioned default setting for storage. local. target-heap-size , you will be limited to about 200,000 time series simultaneously present in memory.

## How many Prometheus metrics are there?

four

The Prometheus client libraries offer four core metric types.

**What are buckets in Prometheus?**

Prometheus stores histograms internally in buckets that have a max size (labeled le ), but no minimum size. You must configure the number and max size of each bucket ahead of time. Each bucket time series will contain the count of observations that was less than or equal to its le value for a given timestamp.

### Why are metrics used?

Metrics help transform the vague requirements that a customer gives into a series of numbers that can be used to accurately map the process for its efficiency. Metrics tell us whether a process is good enough to meet the customer’s requirements or whether it needs to be better.

**What is JVM micrometer?**

A dashboard for Micrometer instrumented applications (Java, Spring Boot, Micronaut).

#### What is IO micrometer?

Micrometer is a simple application metrics facade for the JVM. It has become the defacto standard in the Java ecosystem and is integrated into SpringBoot. Read more on Micrometer at micrometer.io. Instana supports Micrometer without any additional configuration.

**What is bucket in histogram?**

A histogram displays numerical data by grouping data into “bins” of equal width. Each bin is plotted as a bar whose height corresponds to how many data points are in that bin. Bins are also sometimes called “intervals”, “classes”, or “buckets”.

## What DB is used by Prometheus?

Prometheus has a sophisticated local storage subsystem. For indexes, it uses LevelDB.

**What is Prometheus and Grafana?**

Grafana and Prometheus are probably the most prominent tools in the application monitoring and analytics space. Prometheus is an open source monitoring and alerting platform which collects and stores metrics as time-series data. Grafana is an open source analytics and interactive visualization web application.