11.1.1. Tracking Configuration History
The ETL service tracks three types of changes:
A new entity is added to the rhevm database - the ETL Service replicates the change to the rhevm_history database as a new entry.
An existing entity is updated - the ETL Service replicates the change to the rhevm_history database as a new entry.
An entity is removed from the rhevm database - A new entry in the rhevm_history database flags the corresponding entity as removed. Removed entities are only flagged as removed. To maintain correctness of historical reports and representations, they are not physically removed.
The configuration tables in the
rhevm_history database differ from the corresponding tables in the
rhevm database in several ways. The most apparent difference is they contain fewer
configuration columns. This is because certain configuration items are less interesting to report than others and are not kept due to database size considerations. Also, columns from a few tables in the
rhevm database appear in a single table in
rhevm_history and have different column names to make viewing data more convenient and comprehensible. All configuration tables contain:
a history_id
to indicate the configuration version of the entity;
a create_date
field to indicate when the entity was added to the system;
an update_date
field to indicate when the entity was changed; and
a delete_date
field to indicate the date the entity was removed from the system.
11.1.2. Recording Statistical History
The ETL service collects data into the statistical tables every minute. Data is stored for every minute of the past 24 hours. Minute-by-minute data more than two hours old is aggregated into hourly data and stored for two months. Hourly data more than two days old is aggregated into daily data and stored for five years.
Hourly data and daily data can be found in the hourly and daily tables.
Each statistical datum is kept in its respective aggregation level table: samples, hourly, and daily history. All history tables also contain a history_id column to uniquely identify rows. Tables reference the configuration version of a host in order to enable reports on statistics of an entity in relation to its past configuration.
11.1.3. Tracking Tag History
The ETL Service collects tag information as displayed in the Administration Portal every minute and stores this data in the tags historical tables. The ETL Service tracks five types of changes:
A tag is created in the Administration Portal - the ETL Service copies the tag details, position in the tag tree and relation to other objects in the tag tree.
A entity is attached to the tag tree in the Administration Portal - the ETL Service replicates the addition to the rhevm_history database as a new entry.
A tag is updated - the ETL Service replicates the change of tag details to the rhevm_history database as a new entry.
An entity or tag branch is removed from the Administration Portal - the rhevm_history database flags the corresponding tag and relations as removed in new entries. Removed tags and relations are only flagged as removed or detached. In order to maintain correctness of historical reports and representations, they are not physically removed.
A tag branch is moved - the corresponding tag and relations are updated as new entries. Moved tags and relations are only flagged as updated. In order to maintain correctness of historical reports and representations, they are not physically updated.