Merging of sorted lists using array pair

Patent metadata

Field	Value
Publication number	US-9418089-B2
Application number	US-201313892799-A
Country	US
Kind code	B2
Filing date	May 13, 2013
Priority date	May 13, 2013
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

The formulation of a merged sorted list from multiple input sorted lists in multiple phases using an array pair. Initially, the first array is contiguously populated with the input sorted lists. In the first phase, the first and second input sorted lists are merged into a first intermediary merged list within the second array. Each subsequent phase merges a prior intermediary merged list resulting from the prior phase and, a next input sorted list in the first array to generate a next intermediary merged list, or a merged sorted list if there or no further input in the first array. The intermediary merged lists alternate between the first array and the second array from one phase to the next phase.

First claim

What is claimed is:

1. A computer program product comprising one or more computer-readable storage media having thereon computer-executable instructions that are structured such that, when executed by one or more processors of the computing system, cause the computing system to perform a method comprising an act of merging a plurality of sorted lists to form a merged sorted list, the act merging the plurality of sorted lists comprising:
an act representing a first sorted list and a second sorted list contiguously in a first plurality of elements in a first array in memory
an act of establishing a first input cursor at the first element in the first sorted list in the first array;
an act of establishing a second input cursor at the first element in the second sorted list in the first array;
an act of formulating a second array in memory, the second array including at least a portion that includes a second plurality of elements equal in number to the first plurality of elements;
an act of sequentially assigning values to the elements of the second plurality of elements to thereby formulated a first merged sorted list of the first and second sorted lists,
the act of sequentially assigning comprising performing the following for each of the first element through a subsequent element in the secondary plurality of elements:
an act of comparing a value at an element pointed to by the first input cursor with a value at the element pointed to by the second input cursor;
if the value at the element pointed to by the first input cursor satisfies a sorting priority with respect to the value at the element pointed to by the second input cursor; an act of populating the corresponding element of the second plurality of elements with the value at the element pointed to by the first input cursor; and an act of moving the first input cursor to a next element in the first sorted list of the first plurality of elements if there are any further elements in the first sorted list, and if there are not any further elements in the first sorted list, the corresponding element of the second plurality of elements is the subsequent element of the second plurality of elements, and thus the method further includes an act of further populating a remainder of the second plurality of elements with any remaining unprocessed elements of the second sorted list from an element pointed to by the second input cursor; and
if the value at the element pointed to by the first input cursor does not satisfy a sorting priority with respect to the value at the element pointed to by the second input cursor; an act of populating the corresponding element of the second plurality of elements with the value at the element pointed to by the second input cursor; and an act of moving the second input cursor to a next element in the second sorted list of the first plurality of elements if there are any further elements in the second sorted list, and if there are not any further elements in the second sorted list, the corresponding element of the second plurality of elements is the subsequent element of the second plurality of elements, and thus the method further includes an act of further populating a remainder of the second plurality of elements with any remaining unprocessed elements of the first sorted list from an element pointed to by the first input cursor.

2. The computer program product in accordance with claim 1 , wherein the first array includes a third sorted list arranged contiguously with the first plurality of elements in the first array to form a first superset plurality of elements in the first array, the method further comprising an act of merging the first merged sorted list with the third sorted list comprising:
an act of establishing the first input cursor at the first element in the first merged sorted list in the second plurality of elements in the second array;
an act of establishing a second input cursor at the first element in the third sorted list in the first array;
an act of sequentially assigning values to the elements of the first superset plurality of elements in the first array to thereby formulate a second merged sorted list of the first, second and third sorted lists,
the act of sequentially assigning values to the elements of the first superset plurality of elements comprising performing the following for each of the first element through a subsequent element in the first superset plurality of elements:
an act of comparing a value at an element pointed to by the first input cursor with a value at the element pointed to by the second input cursor;
if the value at the element pointed to by the first input cursor satisfies the sorting priority with respect to the value at the element pointed to by the second input cursor; an act of populating the corresponding element of the first superset plurality of elements with the value at the element pointed to by the first input cursor; and an act of moving the first input cursor to a next element in the first merged sorted list of the first plurality of elements if there are any further elements in the first merged sorted list, and if there are not any further elements in the first merged sorted list, the corresponding element of the first superset plurality of elements is the subsequent element of the first superset plurality of elements, and thus the method further includes an act of further populating a remainder of the first superset plurality of elements with any remaining unprocessed elements of the third sorted list from an element pointed to by the second input cursor; and
if the value at the element pointed to by the first input cursor does not satisfy the sorting priority with respect to the value at the element pointed to by the second input cursor; an act of populating the corresponding element of the first superset plurality of elements with the value at the element pointed to by the second input cursor; and an act of moving the second input cursor to a next element in the third sorted list of the first array if there are any further elements in the third sorted list, and if there are not any further elements in the third sorted list, the corresponding element of the first superset plurality of elements is the subsequent element of the first superset plurality of elements, and thus the method further includes an act of further populating a remainder of the first superset plurality of elements with any remaining unprocessed elements of the first merged sorted list from an element pointed to by the first input cursor.

3. The computer program product in accordance with claim 1 , wherein the plurality of sorted lists is a first plurality of sorted lists, and the merged sorted list is a first merged sorted list, the method further comprising:
an act of persisting in sort order those higher prioritized values of the merged sorted list that have a more prioritized sort priority;
an act of removing the persisted values from the first plurality of sorted lists;
an act of accessing at least one additional element;
an act of formulating a second plurality of sorted lists using a combination of the at least one additional element and any remaining sorted lists of the first plurality of the sorted lists that remain after the act of removing; and
an act of formulating a second merged sorted list using the second plurality of sorted lists.

4. The computer program product in accordance with claim 1 , wherein the act of merging the plurality of sorted lists to form the merged sorted list is performed in response to an act of detecting a notification that additional sorted lists in a stream of sorted lists that are beyond the plurality of sorted lists only include values that have lower prioritized sort priority than any of the values in the plurality of sorted lists.

5. The computer program p

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Goldstein Jonathan David
• Chandramouli Badrish

Classifications

• G06F2207/224

  External sorting · CPC title

• G06F16/245

  Query processing · CPC title

• G06F16/2237 Primary

  Vectors, bitmaps or matrices · CPC title

• G06F16/22

  Indexing; Data structures therefor; Storage structures · CPC title

• G06F16/217

  Database tuning (G06F16/2282 takes precedence; database performance monitoring G06F11/3409) · CPC title