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Asset contents or previews

Last updated: Mar 28, 2025
Asset contents or previews

In projects and other workspaces, you can see a preview of data assets that contain relational data.

Requirements and restrictions

You can view the contents or asset previews under the following conditions and restrictions.

Workspaces

You can view the preview or asset contents in these workspaces:

  • Projects

Required permissions

You can see the asset contents or preview with any collaborator role in the workspace.

Restrictions for data assets

Additional requirements apply to connected data assets and data assets from files. See Requirements for data assets.

Previews are not available for data assets that were added as managed assets by using the Data and AI Common Core API.

Limitations

  • In catalogs or projects, you might not see previews or profiles of connected data assets that are associated with connections that require personal connections. You must enter your personal credentials to start the preview or profiling of the connection asset.
  • In a catalog, you might not see previews of JSON, text, or image files that were published from a project.
  • In a catalog, the previews of JSON and text files that are accessed through a connection might not be formatted correctly.
  • In a catalog, you can't preview data assets that contain array columns.
  • In a project, you can't view the previews of image files that are accessed through a connection.

Asset types with previews

The following types of assets have previews:

  • Data assets from files
  • Connected data assets
  • Models
  • Notebooks

Previews of data assets

The previews of data assets show a view of the data.

You can see when the data in the preview was last fetched and refresh the preview data by clicking the refresh icon.

Requirements for data assets

The additional requirements for viewing previews of data assets depend on whether the data is accessed through a connection or from a file.

  • Connected data assets
    You can see previews of data assets that are accessed through a connection if all these conditions are true:

    • You have access to the data asset and its associated connection. See Requirements and restrictions.
    • The data asset contains structured data. Structured data resides in fixed fields within a record or file, for example, relational database data or spreadsheets.
    • You have credentials for the connection:
      • For connections with shared credentials, the username in the connection details has access to the object at the data source.
      • For connections with personal credentials, you must enter your personal credentials when you see a key icon the key symbol for private connections. This is a one-time step that permanently unlocks the connection for you. See Adding connections to projects.

  • Data assets from files
    You can see previews of data assets from files if the following conditions are true:

    • You have access to the data asset. See Requirements and restrictions.

    • The file is stored in IBM Cloud Object Storage. For preview of text or image files from an IBM Cloud Object Storage connection to work, the connection credentials must include an access key and a secret key. If you’re using an existing Cloud Object Storage connection that doesn’t have these keys, edit the connection asset and add them. See IBM Cloud Object Storage connection.

    • The file type is supported. See File extensions and mime types of previewed files.

    • The content has UTF-8 encoding.

Preview information for data assets

For structured data, the preview displays a limited number of rows and columns:

  • The number of rows in the preview is limited to 1,000.
  • The amount of data is limited to 800 KB. The more columns the data asset has, the fewer rows that appear in the preview.

Previews show different information for different types of data assets and files.

  • Structured data
    For structured data, the preview shows column names, a subset of columns and rows of data. The supported formats for structured data include relational data, CSV, TSV, Avro, Microsoft Excel documents, and partitioned Parquet data (for IBM Cloud Object Storage and S3 connections). Microsoft Excel documents show the first sheet.

    Assets from file based connections like Apache Kafka and Apache Cassandra are not supported.

  • Unstructured data
    Unstructured data files must be stored in IBM Cloud Object Storage to have previews.

    For these unstructured data files, the preview shows the whole document: Text, JSON, HTML, PDF, and images. HTML files are supported in text format. Images stored in IBM Cloud Object Storage support JPG, JPEG, PNG, GIF, BMP, and BMP1.

    For connected folder assets, the preview shows the files and subfolders, which you can also preview.

File extensions and mime types of previewed files

These types of files that contain structured data have previews:

Table 1. Structured data files with previews
Extension Mime type
AVRO
CSV text/csv
CSV1 application/csv
PARQ
TSV
XLSX application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
XLS application/vnd.ms-excel
XLSM application/vnd.ms-excel.sheet.macroEnabled.12

These types of image files have previews:
Table 2. Image files with previews
Extension Mime type
BMP image/bmp
GIF image/gif
JPG image/jpeg
JPEG image/jpeg
PNG image/png

These types of document files have previews:
Table 3. Document files with previews
Extension Mime type
HTML text/html
PDF application/pdf
TXT text/plain

Learn more

Parent topic: Asset types and properties