Datalake - Query Language

Now that we are able to visualize, structure, and order Data from the Datalake, the next step would be to retrieve it in an efficient way.

1. Search Bar

To do so, the best tool is the Search Bar and its associated Query Language.

👍

This Search Bar is accessible in each image overview of the Picsellia platform.

2. Query Language

The Query Language is used in the Search Bar to filter among Data from the Datalake.

It allows users to access all Data properties and sub-properties to search on them to find Data satisfying the query.

A. Objects & Metadata available for searching

As for now, we are dealing with the search bar available in the Datalake, you will be able to search on all the objects and Metadata associated with Picsellia Data:

Please note that in this list some fields are other Picsellia objects that are linked to Picsellia Data. It means that from the Datalake Search Bar, you can go deeper into the Picsellia Object Schema to filter on Data that are linked to another Picsellia Object.

For instance, we can retrieve all the Data from the Datalake that are part of a specific DatasetVersion with the following query:

datasets.version = "MyDatasetVersion"

To browse through the QueryLangage across the Picsellia Object Schema, it is highly recommended to use the auto-completion proposed by the Search Bar.

In the end, the last element you are filtering on must be a property of either Data or of an object linked to Data.

In the previous example, datasets is the object linked to Data, and version is the property of this object linked to Data. However filename is a property of Data so you can directly search for it:

filename = "FileNameOfMyData"

B. Comparison

Depending on the format of the object property you are filtering on, several comparison signs are proposed by the auto-completion engine:

• For string:

• For integers or floats:

C. Logical connector

In order to perform the most accurate filtering possible among your Datalake, you can create complex queries leveraging the and & or logical connectors.

At the end of the first query element after leaving one space, the auto-completion engine will propose you the logical connector to your query.

3. Data satisfying the query

After having written your query, you just need to press the Enter key to run the query. The Data from your Datalake satisfying the query will then be displayed.

📘

To delete a query from the Search Bar

you just need to click the cross icon to the right of the Search Bar.

It means that after having filtered through the Search Bar on your Datalake, the only Data displayed in your Datalake overview are the ones matching the query. The number of Data matching is displayed on top of the Datalake as shown below:

👍

What's next

Now that you can filter among the Datalake to retrieve the Data you're interested in, you can leverage the ordering and selecting features of Picsellia to manipulate your Data and create your Dataset.