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Long- and short-term statistics

Home Assistant has support for both short- and long-term statistics. For short-term statistics a snapshot is taken every 5 minutes. It keeps track of supported entities and different elements of the entity state. For long-term statistics, an hourly aggregate is stored of the short-term statistics. Currently two types of entities are differentiated for statistics:

  • Sensor entities with a measurement, such as the current temperature. It will store the hourly min, max, and mean value.
  • Sensor entities that are metered, such as the daily energy consumption. It will store the growth of that entity.

Short- and long-term statistics are different than entries in the states table of the database. The states table stores objects exactly as they happened. The states and statistics_short_term tables are automatically purged after a predefined period (default is 10 days). The long-term statistics table is never purged. Because it stores an hourly summary, only 24 entries are created per day.

Read the sensor developer documentation on how to configure entities to be tracked by the long-term statistics.

Database tables

Long-term statistics consists of three tables. One contains the metadata, the other two contain the data.

  • statistics_meta: Metadata describing the data source.
  • statistics_short_term: 5-minutes aggregates of data from the states table.
  • statistics: Hourly aggregates of the data from the statistics_short_term table.

Statistics Meta

The Statistics Meta table contains the metadata describing the source. Statistics are either derived from entities, in which case statistic_id is equivalent to the entity_id, or imported from an external source. Statistics imported from an external source are similar to entity_id, but use a : instead of a . as a delimiter between the domain and object ID.

If an entity ID of an entity is changed, the statistic ID is automatically updated.

idColumn(Integer, primary_key=True)
statistic_idColumn(String(255), index=True)

Statistics data tables

Short- and long-term statistics tables

The statistics_short_term table stores 5-minute aggregates of the data from the states table. The statistics table contains the long-term statistics data. It stores hourly aggregates of the data from the statistics_short_term table. For both tables, Depending on the entity type, different data is tracked.

  • Sensor entities with a measurement (the sensor's state_class is measurement):
    • mean - 5-minute / hourly time-weighted average
    • min - 5-minute / hourly minimum
    • max - 5-minute / hourly maximum
  • Sensor entities that have a value which is integrated over time, such as utility meters (the sensor's state_class is total or total_increasing):
    • last_reset_ts - the timestamp when the last meter cycle was started, if known
    • state - the sensor's state at the end of the hour
    • sum - hourly grand total since statistics for the sensor was first compiled, offset by the sensor's first valid state when compiling statistics. Please refer to the developer documentation for how the sum is calculated.
idColumn(Integer, primary_key=True)
created_tsColumn(DOUBLE_TYPE(), default=time.time)
metadata_idColumn(Integer, ForeignKey(f"{TABLE_STATISTICS_META}.id", ondelete="CASCADE"))
start_tsColumn(DOUBLE_TYPE(), index=True)

Statistics runs

This table is used to keep track of hours for which statistics have been compiled.

run_idColumn(Integer, primary_key=True)

Data visualization

The short- and long-term statistics data is used as a data source in various places in Home Assistant.