Shared Sample Stores

In ado Entities and measurement results are stored in a database called Sample Store. This document describes how Sample Stores enable sharing of data. For more general information about these databases see their dedicated page.

From the point-of-view of understanding data reuse in ado, the following points are key:

• You can share a Sample Store between multiple Discovery Spaces
• This allows a Discovery Space to (re)use relevant Entities and Measurements placed in the Sample Store by operations on other Discovery Spaces
• Entities are always shared. There is only one entry in a Sample Store for an Entity

When data can be shared in ado¶

There are two situations where data can be shared between Discovery Spaces in ado:

• Data Retrieval: retrieving data about entities and measurements from the Discovery Space e.g. ado show entities space
• Data Generation: When performing an explore operation on a Discovery Space - we call data reuse in this case memoization

How ado determines what data can be shared¶

As a quick recap, a Discovery Space is composed of:

• an Entity Space which describes a set of Entities (points) to be measured
• a Measurement Space which describes a set of Experiments to apply to the points

Entities¶

Each Entity in the Entity Space has a unique identifier, usually determined by its set of constitutive property values. For example, if an Entity has two constitutive properties X an Y with values 4 and 10, its id will be 'X:4-Y:10'. Since the identifiers of all the Entities in the Entity Space are known, the Sample Store can be searched to see if it contains a record for any of the Entities.

Measurements¶

Each Experiment in a Measurement Space also has a unique identifier, determined from its base name plus any optional properties that have been explicitly set. When an Entity is retrieved from the Sample Store, it contains results of all the experiments that have been applied to it. If the identifier of a result matches the identifier of an Experiment in the Measurement Space, ado determines it can be reused.

Data sharing and data retrieval¶

When retrieving data from a Discovery Space, e.g. via ado show entities, you are actually retrieving data from the Sample Store that matches the Discovery Space. When determining what data to retrieve there are two situations to consider:

• measured: retrieve only Entities and measurements that were sampled via an operation on the given Discovery Space
• this can be considered the "no sharing" mode. If an Entity or measurement exists in the Sample Store that's compatible with the Discovery Space, but no operation on the Discovery Space ever visited it, the "measured" mode will not show it
• matching: retrieve all Entities and measurements that match the Discovery Space
• this can be considered the "sharing" mode.

Data sharing and memoization¶

This section explains how data sharing and reuse works during an explore operation - a feature called memoization. It's recommended you check the documentation on operations and explore operators.

Briefly, an explore operation samples a point in the Entity Space of a Discovery Space and applies the experiments in the Measurement Space to it. In detail, the sampling process is as follows:

• An Entity is sampled from the Entity Space
• The Entity's record is retrieved from the Sample Store if present (via its unique identifier)
• If memoization is on
• for each experiment in the MeasurementSpace, ado checks if a result for it already exists (via the experiment's unique identifier)
  • if it does, the result is reused. If there is more than one result, they are all reused
• if memoization is off
• Existing results are ignored. Each experiment in the Measurement Space is applied again to the Entity. The new results are added to any existing.