Catalog - Preview Table

Service:

Data Lake Analytics

API Version:

2016-11-01

Retrieves a preview set of rows in given table.

GET https://{accountName}.{adlaCatalogDnsSuffix}/catalog/usql/databases/{databaseName}/schemas/{schemaName}/tables/{tableName}/previewrows?api-version=2016-11-01

With optional parameters:

GET https://{accountName}.{adlaCatalogDnsSuffix}/catalog/usql/databases/{databaseName}/schemas/{schemaName}/tables/{tableName}/previewrows?maxRows={maxRows}&maxColumns={maxColumns}&api-version=2016-11-01

URI Parameters

Name	In	Required	Type	Description
accountName	path	True	string	The Azure Data Lake Analytics account upon which to execute catalog operations.
adlaCatalogDnsSuffix	path	True	string	Gets the DNS suffix used as the base for all Azure Data Lake Analytics Catalog service requests.
databaseName	path	True	string	The name of the database containing the table.
schemaName	path	True	string	The name of the schema containing the table.
tableName	path	True	string	The name of the table.
api-version	query	True	string	Client Api Version.
maxColumns	query		integer (int64)	The maximum number of columns to be retrieved.
maxRows	query		integer (int64)	The maximum number of preview rows to be retrieved. Rows returned may be less than or equal to this number depending on row sizes and number of rows in the table.

Responses

Name	Type	Description
200 OK	USqlTablePreview	Successfully retrieved preview rows for the specified table.

Examples

Retrieves a preview set of rows in given table

Sample request

HTTP

GET https://contosoadla.azuredatalakeanalytics.net/catalog/usql/databases/master/schemas/dbo/tables/test_table_name/previewrows?api-version=2016-11-01

Sample response

Status code:

200

{
  "totalRowCount": 1,
  "totalColumnCount": 2,
  "rows": [
    [
      "value_a",
      "value_b"
    ]
  ],
  "truncated": false,
  "schema": [
    {
      "name": "test_column_name",
      "type": "test_data_type"
    }
  ]
}

Definitions

Name	Description
USqlTableColumn	A Data Lake Analytics catalog U-SQL table column item.
USqlTablePreview	A Data Lake Analytics catalog table or partition preview rows item.

USqlTableColumn

Object

A Data Lake Analytics catalog U-SQL table column item.

Name	Type	Description
name	string	the name of the column in the table.
type	string	the object type of the specified column (such as System.String).

USqlTablePreview

Object

A Data Lake Analytics catalog table or partition preview rows item.

Name	Type	Description
rows	string[]	the rows of the table or partition preview, where each row is an array of string representations the row's values. Note: Byte arrays will appear as base-64 encoded values, SqlMap and SqlArray objects will appear as escaped JSON objects, and DateTime objects will appear as ISO formatted UTC date-times.
schema	USqlTableColumn[]	the schema of the table or partition.
totalColumnCount	integer (int64)	the total number of columns in the table or partition.
totalRowCount	integer (int64)	the total number of rows in the table or partition.
truncated	boolean	true if the amount of data in the response is less than expected due to the preview operation's size limitations. This can occur if the requested rows or row counts are too large.