Overview
Data Preview is a key step in the local upload to table process, between Upload File and Storage Settings. On this page, you can: Adjust the field name, field type, and sharding field to finalize the Schema for data storage.
View the first 50 rows of data samples to verify the parsing results.
Table Creation Methods
After parsing the file, you can choose how to create the table:
Method | Action | Scenario |
Create a new table. | Create a new table in the target catalog. | Initial Upload of Scattered Files |
Overwrite an existing table. | Select an existing table and overwrite its data. | Update data in an existing table. |
Storage Location
The target location settings for table creation include two configuration items:
For catalog and schema, you can select a table-type catalog. If no suitable catalog or schema is available, click Create Data Catalog or the plus icon (+) to create a schema.
Table name: If you choose to overwrite an existing table, select an existing table. If you choose to create a new table, enter a table name.
Field Operations
The field headers in the table preview support the following operations:
Operation | Entries | Description |
Alter Field Name. | Click the field name in the table header. | Field names cannot be empty or duplicate; the default value is the name inferred from parsing. |
Modify the field type. | Click the type icon next to the field name. | A type drop-down menu appears, from which you can select STRING / INT / BIGINT / FLOAT / DOUBLE / DECIMAL / BOOLEAN / DATE / TIMESTAMP. |
Set DECIMAL precision. | Select DECIMAL as the field type, hover over it to display the edit icon, and then click it. | Set precision (1–38) and scale (0–precision). For details, see File Parsing and Inference - DECIMAL Precision Settings. |
Select table creation fields. | Select field checkboxes. | Only selected fields are written to the target table, and other fields are not stored. Select at least one field (the last remaining field cannot be cleared). |
Data Preview Table
Feature | Description |
Preview Rows | Display up to 50 rows. |
Number of Data Rows/Columns | Number of rows and columns actually read from the file |
Data Preview Table | Display preview data based on the selected fields. |
Advanced Settings Entry
An Advanced Settings entry is provided above the preview table, allowing you to adjust parsing rules for the current file type. For details, see File Parsing and Inference. Note:
After you modify Advanced Settings, the system reparses the file and refreshes the preview data. If you have previously changed field names or field types manually, edit the fields only after the conversion rules become stable to avoid repeated modifications.
Go to the Next Step
After confirming that the preview data, field names, field types, and archived fields are correct, click Create Table to go to Storage Settings, where you can select the target Catalog/Schema and processing method. For details, see Local Upload to Table - Step 5: Storage Settings. References