/aggregate/unique

URL: https://<aws.fqdn>/<aws.cluster.name>/gpudb-0/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 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

NameTypeDescription
table_namestringName of an existing table or view on which the operation will be performed, in [schema_name.]table_name format, using standard name resolution rules.
column_namestringName of the column or an expression containing one or more column names on which the unique function would be applied.
offsetlongA 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.
limitlongA positive integer indicating the maximum number of results to be returned, or END_OF_SET (-9999) to indicate that the maximum number of results allowed by the server 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.
encodingstring

Specifies the encoding for returned records. The default value is binary.

Supported ValuesDescription
binaryIndicates that the returned records should be binary encoded.
jsonIndicates that the returned records should be json encoded.
optionsmap of string to strings

Optional parameters. The default value is an empty map ( {} ).

Supported Parameters (keys)Parameter Description
create_temp_table

If true, a unique temporary table name will be generated in the sys_temp schema and used in place of result_table. If result_table_persist is false (or unspecified), then this is always allowed even if the caller does not have permission to create tables. The generated name is returned in qualified_result_table_name. The default value is false. The supported values are:

  • true
  • false
collection_name[DEPRECATED--please specify the containing schema as part of result_table and use /create/schema to create the schema if non-existent] Name of a schema which is to contain the table specified in result_table. If the schema provided is non-existent, it will be automatically created.
expressionOptional 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_tableThe name of the table used to store the results, in [schema_name.]table_name format, using standard name resolution rules and meeting table naming criteria. If present, no results are returned in the response. 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
ttlSets the TTL of the table specified in result_table.
chunk_sizeIndicates the number of records per chunk to be used for the result table. Must be used in combination with the result_table option.
view_idID 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:

NameTypeDescription
statusString'OK' or 'ERROR'
messageStringEmpty if success or an error message
data_typeString'aggregate_unique_response' or 'none' in case of an error
dataStringEmpty string
data_strJSON or String

This embedded JSON represents the result of the /aggregate/unique endpoint:

NameTypeDescription
table_namestringThe same table name as was passed in the parameter list.
response_schema_strstringAvro schema of output parameter binary_encoded_response or output parameter json_encoded_response.
binary_encoded_responsebytesAvro binary encoded response.
json_encoded_responsestringAvro JSON encoded response.
has_more_recordsbooleanToo many records. Returned a partial set.
infomap of string to strings

Additional information. The default value is an empty map ( {} ).

Possible Parameters (keys)Parameter Description
qualified_result_table_nameThe fully qualified name of the table (i.e. including the schema) used to store the results.

Empty string in case of an error.