# Metrics Exporter - In-memory

LLMS index: [llms.txt](/llms.txt)

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**Status**: [Stable](../../document-status.md)

In-memory Metrics Exporter is a [Push Metric
Exporter](../sdk.md#push-metric-exporter) which accumulates metrics data in the
local memory and allows to inspect it (useful for e.g. unit tests).

In-memory Metrics Exporter MUST provide configuration to set
the [MetricReader](../sdk.md#metricreader) output `temporality` as a function of
instrument kind. This option MAY be named `temporality`, and MUST set
temporality to Cumulative for all instrument kinds by default.

In-memory Metrics Exporter MAY provide configuration to set
the [MetricReader](../sdk.md#metricreader) default `aggregation` as a function
of instrument kind. This option MAY be named `default_aggregation`, and MUST use
the [default aggregation](../sdk.md#default-aggregation) by default.

If a language provides a mechanism to automatically configure a
[MetricReader](../sdk.md#metricreader) to pair with the associated
exporter (e.g., using the [`OTEL_METRICS_EXPORTER` environment
variable](../../configuration/sdk-environment-variables.md#exporter-selection)), by
default the exporter MUST be paired with a [periodic exporting
MetricReader](../sdk.md#periodic-exporting-metricreader).