SORT(recordset,value [, JOINED( joinedset )][, SKEW( limit [,target] )] [, THRESHOLD( size )][, LOCAL] [,FEW] [, STABLE [ ( algorithm )] | UNSTABLE [ ( algorithm )] ] [, UNORDERED | ORDERED( bool ) ] [, PARALLEL [ ( numthreads ) ] ] [, ALGORITHM( name ) ] )
| recordset | The set of records to process. This may be the name of a dataset or a record set derived from some filter condition, or any expression that results in a derived record set. |
| value | A comma-delimited list of expressions or key fields in the recordset on which to sort, with the leftmost being the most significant sort criteria. A leading minus sign (-) indicates a descending-order sort on that element. You may have multiple value parameters to indicate sorts within sorts. You may use the keyword RECORD (or WHOLE RECORD) to indicate an ascending sort on all fields, and/or you may use the keyword EXCEPT to list non-sort fields in the recordset. |
| JOINED | Optional. Indicates this sort will use the same radix-points as already used by the joinedset so that matching records between the recordset and joinedset end up on the same supercomputer nodes. Used to optimize supercomputer joins where the joinedset is very large and the recordset is small. |
| joinedset | A set of records that has been previously sorted by the same value parameters as the recordset. |
| SKEW | Optional. Indicates that you know the data is not spread evenly across nodes (is skewed) and you choose to override the default by specifying your own limit value to allow the job to continue despite the skewing. |
| limit | A value between zero (0) and one (1.0 = 100%) indicating the maximum percentage of skew to allow before the job fails (the default is 0.1 = 10%). |
| target | Optional. A value between zero (0) and one (1.0 = 100%) indicating the desired maximum percentage of skew to allow (the default is 0.1 = 10%). |
| THRESHOLD | Optional. Indicates the minimum size for a single part of the recordset before the SKEW limit is enforced. |
| size | An integer value indicating the minimum number of bytes for a single part. |
| LOCAL | Optional. Specifies the operation is performed on each node independently, without requiring interaction with all other nodes to acquire data; the operation maintains the distribution of any previous DISTRIBUTE. An error occurs if the recordset has been GROUPed. |
| FEW | Optional. Specifies that few records will be sorted. This prevents spilling the SORT to disk if another resource-intensive activity is executing concurrently. |
| STABLE | Optional. Specifies a stable sort--duplicates output in the same order they were in the input. This is the default if neither STABLE nor UNSTABLE sorting is specified. Ignored if not supported by the target platform. |
| algorithm | Optional. A string constant that specifies the sorting algorithm to use (see the list of valid values below). If omitted, the default algorithm depends on which platform is targeted by the query. |
| UNSTABLE | Optional. Specifies an unstable sort--duplicates may output in any order. Ignored if not supported by the target platform. |
| UNORDERED | Optional. Specifies the output record order is not significant. |
| ORDERED | Specifies the significance of the output record order. |
| bool | When False, specifies the output record order is not significant. When True, specifies the default output record order. |
| PARALLEL | Optional. Try to evaluate this activity in parallel. |
| numthreads | Optional. Try to evaluate this activity using numthreads threads. |
| ALGORITHM | Optional. Override the algorithm used for this activity. |
| name | The algorithm to use for this activity. Must be from the list of supported algorithms for the SORT function's STABLE and UNSTABLE options. |
| Return: | SORT returns a set of records. |
The SORT function orders the recordset according to the values specified, and (if LOCAL Is not specified) partitions the result such that all records with the same values are on the same node. SORT is usually used to produce the record sets operated on by the DEDUP, GROUP, and ROLLUP functions, so that those functions may operate optimally. Sorting final output is, of course, another common use.
There are three sort algorithms available: quicksort, insertionsort, and heapsort. They are not all available on all platforms. Specifying an invalid algorithm for the targeted platform will generate a warning and the default algorithm for that platform will be implemented.