Data Preparation FAQs

What is a Business View?

A Business View is a logical data model. Consider a logical collection of tables that are linked by a common key (date, ID etc). When building a Business View, one has to build a dataset for modeling rather than creating a relational database.

What happens if Business Views are downloaded as CSV?

The portion displayed under Data -> Business View will be downloaded as a single table.

What is the difference between a Business View and a Project?

A Business View is the logical data model used to drive Search, Vizpads, Insights, and Models. A Project is akin to a folder that contains a collection of Vizpads, Insights, and Models for a particular Business View. Once a project is shared with other users, all of its contents are shared automatically.

Can I create a new dataset within Tellius using SQL or Python?

No, you can only add or remove columns in the existing dataset. A self-join of datasets is possible in some instances.

What is the difference between column type and feature type?

Column types can be measures or dimensions. Feature types can be categorical or continuous. Check out the documentation on column type and feature type.

How do I refer to null values in the signature function? I have tried multiple versions, and none work (null, NULL, “NULL”, “null”).

For this purpose, you need to use SQL or Python. Functions do not support reference to null values.

How do I set the incremental data refresh, i.e., do not replace it, but append it during a refresh?

Only full replacement is available for local files. Incremental can be set up for databases.

Where is the data located after the connection is established?

The data is loaded into memory and also stored on disk.

How to handle actual time stamp columns? For example, converting a string "12:12:11" to a timestamp, using hh:mm:ss format does not work as the date is set to Jan 1, 1970.

This manipulation need to be done using SQL or Python.

If I need to go back into the data pipeline and modify a node, will the subsequent node be updated?

Yes. SQL, Python, and advanced filter nodes can be modified in the middle of the data pipeline without having to modify the subsequent node. If a node is no longer needed, keep the node without a script.

The values with dollar signs are imported as strings. How to handle the transformation into a num?

It's recommended to remove the dollar sign, comma, and periods (for decimals) using find & replace via SQL or Python. Then, it needs to be converted into a number. Or, you could directly convert it into a number via SQL or Python.

What is Live query mode? What are the cons of that approach?

Live datasets reside in the source, and they are not imported to Tellius. So for each query, the data needs to be fetched from the source, which could take a bit of time (when compared to non-live datasets). It can only be used for driving Search and Vizpads, but not Insights or ML models.

What are the databases that work with the Live query engine?

Redshift, Snowflake, Bigquery, Teradata work with Live query engines.

What is the difference between measures and dimensions?

Measures are quantitative values (e.g., profit, sales, weight) for which you can apply aggregation. Dimensions are qualitative values (e.g., city, name) for which aggregation cannot be applied. Check out this section for more details.

Is there a way to see an audit trail of each transformation made on the dataset so I can undo/revert changes?

Yes. Data Pipeline contains the audit trail of all transformations done to a dataset. The pipeline is tied to a dataset. So, if a dataset is deleted, its pipeline will also be deleted.

Can we incorporate formulas, nested queries, or complex joins within the search criteria and join them with specific keywords?

It is absolutely possible to create formulas, nested queries, and complex joins, which can be used in search queries. New business KPIs and calculated metrics can also be created and used in Search and Vizpads.

Does Tellius support the loading of large data sets in bulk? If so, what are the relative speeds?

Yes. Tellius supports live connections and loading in bulk. The speed depends on the size of the data, resources for the instance, and underlying data source.

When using a SQL script for a live connection, how does it run, and what's the impact on performance? For instance, will a window function in the script execute with every front-end query?

In live connections, any SQL script, including a window function, will execute with each Search/Vizpad query run. To avoid this, consider creating a Materialized View on the source system and then load it to Tellius.

What SQL dialect is used for calculated columns within live connections?

The SQL dialect for calculated columns is compatible with both Spark and the source system from which the data is loaded.

What is the expected behavior when the FQE is toggled on for a live Business View (BV)?

Enabling FQE on a live BV is not applicable. If toggled on, the system will not ingest the data into FQE; live connection status will be maintained. Please avoid using the FQE toggle for live BVs.