Learn how to preview single-table data and explore data through visual queries, SQL, and image-based similarity search in the DLF console.
Use cases
Data Preview works well when you need to:
Get a quick look at the content and distribution of a table.
Spot-check whether data meets expectations with sampled previews.
View actual field values to verify the table schema.
Run simple single-table queries without leaving the console.
Data Discovery is a better fit when you need to:
Filter and preview data through a visual interface.
Run cross-table queries and aggregate analysis with custom SQL.
Export result sets.
Image search works well when you need to:
Validate multimodal retrieval results and test vector recall quality.
Upload a reference image and retrieve similar images from pre-configured embedding columns, without building a separate vector search service.
Both features use Default Compute Resource and are best suited for quick exploration of small datasets. For large-scale analysis, use dedicated compute engines such as Realtime Compute for Apache Flink, EMR Serverless Spark, or EMR Serverless StarRocks.
Pricing
Data Preview and Data Discovery are currently in beta and free to use.
Prerequisites
You need SELECT permission on the target table. To grant permissions, see Manage data permissions.
Data preview
Log on to the DLF console.
In the left-side navigation pane, choose Catalogs. In the catalog tree, navigate to the target Catalog > Database > Table.
On the table details page, click the Data Preview tab.
Visual query
In the Output Fields section, select the columns to return. Select Select All (*) to include all fields, or pick specific fields to preview.
(Optional) In the Filter Conditions section, add WHERE conditions to filter the data. You can use common comparison operators and logical combinations. If no filter is set, all data is returned.
(Optional) In the Advanced Query section, configure advanced options:
Group By: Aggregate results by one or more fields.
Order By: Sort results by one or more fields.
Limit: Set a maximum number of rows to return.
Click Run to run the query. To start over, click Reset.
Queries on large tables may time out due to Default Compute Resource limits. Use Limit and filter conditions to narrow the result set.
Image search
For tables that contain multimodal data (such as image embedding columns), data preview supports an image search mode. Upload a reference image, and the system computes its vector and returns the Top N similar images — no separate vector search service required.
Open a multimodal table and go to the Data Preview tab. In the query configuration area, switch to Image search mode.
Upload a reference image and set the number of results (Top N) to return.
Select a Compute Resource and click Run. Results are ranked by vector similarity in descending order.
Data discovery
Log on to the DLF console.
In the left-side navigation pane, choose Data Discovery.
Choose an exploration mode:
Visual Exploration: Filter and preview data visually without writing SQL. The system generates SQL automatically based on your selections.
SQL Discovery: Write and run SQL queries directly. Includes syntax highlighting, validation, and result set export.
Image search: Upload a reference image to retrieve similar images from pre-configured embedding columns. The system computes the vector automatically and returns the Top N results. Useful for multimodal retrieval validation and vector recall testing.
You can switch between modes at any time from the top of the page.
Visual query
In the query configuration area, select a Catalog, Database, and Table.
In the Output Fields section, select the columns to return. Select Select All (*) to include all fields, or pick specific fields.
(Optional) In the Filter Conditions section, add WHERE conditions to filter the data.
(Optional) In the Advanced Query section, configure advanced options:
Group By: Aggregate results by one or more fields.
Order By: Sort results by one or more fields.
Limit: Set a maximum number of rows to return.
Click Run to run the query. To start over, click Reset.
SQL query
In the Query List on the left, click + (New Query) to open a query editor tab.
Select the target catalog and database in the SQL editor.
Write a query. The editor provides syntax highlighting and validation.
Example:
SELECT col1, col2, COUNT(*) AS cnt FROM my_table WHERE dt = '2024-01-01' GROUP BY col1, col2 ORDER BY cnt DESC LIMIT 100;Click Run to view results.
(Optional) Review past queries in the Query List and export result sets as needed.
Image search
In the query configuration area, select a Catalog, Database, and Table.
In the Image vector section, select the multimodal field (image field) to use for image search. A prompt appears when the table supports image-based retrieval on the selected field.
In the Query image section, upload a query image and set the number of results to return.
Select a Compute Resource and click Run to run the query. To start over, click Reset.