/aggregate/unique

URL: http://GPUDB_IP_ADDRESS:GPUDB_PORT/aggregate/unique

Returns all the unique values from a particular column (specified by input parameter column_name) of a particular table or view (specified by input parameter table_name). If input parameter column_name is a numeric column the values will be in output parameter binary_encoded_response. Otherwise if input parameter column_name is a string column the values will be in output parameter json_encoded_response. The results can be paged via the input parameter offset and input parameter limit parameters.

Columns marked as store-only are unable to be used with this function.

To get the first 10 unique values sorted in descending order input parameter options would be:

{"limit":"10","sort_order":"descending"}.

The response is returned as a dynamic schema. For details see: dynamic schemas documentation.

If a result_table name is specified in the input parameter options, the results are stored in a new table with that name--no results are returned in the response. Both the table name and resulting column name must adhere to standard naming conventions; any column expression will need to be aliased. If the source table's shard key is used as the input parameter column_name, the result table will be sharded, in all other cases it will be replicated. Sorting will properly function only if the result table is replicated or if there is only one processing node and should not be relied upon in other cases. Not available if the value of input parameter column_name is an unrestricted-length string.

Input Parameter Description

Name	Type	Description
table_name	string	Name of an existing table or view on which the operation will be performed.
column_name	string	Name of the column or an expression containing one or more column names on which the unique function would be applied.
offset	long	A positive integer indicating the number of initial results to skip (this can be useful for paging through the results). The default value is 0.The minimum allowed value is 0. The maximum allowed value is MAX_INT.
limit	long	A positive integer indicating the maximum number of results to be returned. Or END_OF_SET (-9999) to indicate that the max number of results should be returned. The number of records returned will never exceed the server's own limit, defined by the max_get_records_size parameter in the server configuration. Use output parameter has_more_records to see if more records exist in the result to be fetched, and input parameter offset & input parameter limit to request subsequent pages of results. The default value is -9999.
encoding	string	Specifies the encoding for returned records. The default value is binary. Supported Values Description binary Indicates that the returned records should be binary encoded. json Indicates that the returned records should be json encoded.
options	map of string to strings	Optional parameters. The default value is an empty map ( {} ). Supported Parameters (keys) Parameter Description collection_name Name of a collection which is to contain the table specified in result_table. If the collection provided is non-existent, the collection will be automatically created. If empty, then the table will be a top-level table. expression Optional filter expression to apply to the table. sort_order String indicating how the returned values should be sorted. The default value is ascending. The supported values are: ascending descending result_table The name of the table used to store the results. If present, no results are returned in the response. Has the same naming restrictions as tables. Not available if input parameter column_name is an unrestricted-length string. result_table_persist If true, then the result table specified in result_table will be persisted and will not expire unless a ttl is specified. If false, then the result table will be an in-memory table and will expire unless a ttl is specified otherwise. The default value is false. The supported values are: true false result_table_force_replicated Force the result table to be replicated (ignores any sharding). Must be used in combination with the result_table option. The default value is false. The supported values are: true false result_table_generate_pk If true then set a primary key for the result table. Must be used in combination with the result_table option. The default value is false. The supported values are: true false ttl Sets the TTL of the table specified in result_table. chunk_size Indicates the number of records per chunk to be used for the result table. Must be used in combination with the result_table option. view_id ID of view of which the result table will be a member. The default value is ''.

Output Parameter Description

The GPUdb server embeds the endpoint response inside a standard response structure which contains status information and the actual response to the query. Here is a description of the various fields of the wrapper:

Name	Type	Description
status	String	'OK' or 'ERROR'
message	String	Empty if success or an error message
data_type	String	'aggregate_unique_request' or 'none' in case of an error
data	String	Empty string
data_str	JSON or String	This embedded JSON represents the result of the /aggregate/unique endpoint: Name Type Description table_name string The same table name as was passed in the parameter list. response_schema_str string Avro schema of output parameter binary_encoded_response or output parameter json_encoded_response. binary_encoded_response bytes Avro binary encoded response. json_encoded_response string Avro JSON encoded response. has_more_records boolean Too many records. Returned a partial set. info map of string to strings Additional information. Empty string in case of an error.