Methods for prefix indexing

• US 8,364,684 B2
• Filed: 10/27/2010
• Issued: 01/29/2013
• Est. Priority Date: 10/27/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Koebler, Eric R., Hrnkvist, John M.
• Primary Examiner(s): Mofiz, Apu
• Assistant Examiner(s): NGUYEN, THU N
• Application Number:
  US12/913,509
• Publication Number:
  US 20120109967A1
• Time in Patent Office: 825 Days
• Field of Search: None
• US Class Current: 707/741
• CPC Class Codes: G06F 16/316 Indexing structures
• CPC Class Codes: G06F 16/901 Indexing; Data structures therefor; Storage structures for retrieval from the web G06F16/951

Abstract

According to one aspect of the invention, in response to one or more terms to be indexed, each of the terms is indexed in a regular index. In addition, for each of the terms having multiple characters, at least one prefix portion of the term is indexed in a prefix index, where the regular index is used for regular searches and the prefix index is used for prefix searches without having to combine a plurality of postings lists of the regular index at the point in time.

Claims

1. A computer-implemented method for indexing one or more terms, comprising:

in response to one or more terms to be indexed, indexing each of the one or more terms in a regular index, the regular index having a plurality of postings lists and each postings list corresponding to a string containing one of the one or more terms; and

for each of the one or more terms having a plurality of characters, indexing at least one prefix portion of each term in a prefix index that is separated from the regular index, wherein the regular index is used for regular searches, and wherein the prefix index is used for prefix searches without having to combine the plurality of postings lists of the regular index at the point in time;

receiving a search query having a search term for searching files that contain the search term from a client;

determining whether a search to be performed is a regular search or a prefix search;

if the search is a regular search, searching in the regular index to identify a plurality of postings lists, each containing the search term, and

returning to the client, a list of item identifiers from the plurality of postings lists obtained from the regular index; and

if the search is a prefix search, searching in the prefix index to identify a single postings list that exactly matches the search term, and

returning to the client, a list of item identifiers from the single postings list;

wherein the regular index and the prefix index are stored in the same file, and wherein each prefix entry of the prefix index is tagged with a marker indicating that the corresponding prefix entry is part of prefix index.

2. The method of claim 1, wherein the prefix portion of a term comprises a leading character and at least one adjacent character of the term.

3. The method of claim 1, wherein each of the terms in the regular index and the prefix index is associated with a postings list having one or more items identifiers identifying one or more files that contain the associated term.

4. The method of claim 1, wherein the one or more terms to be indexed are extracted from at least one of a content data file and metadata of a-the content data file.

5. The method of claim 1, further comprising:

wherein the regular index and the prefix index are inverted indexes.

6. The method of claim 1, wherein the search term for the prefix search is captured and received as a user is typing in a search field.

7. A non-transitory computer-readable storage medium having instructions stored therein, which when executed by a computer, cause the computer to perform a method for indexing, one or more terms, the method comprising:

in response to one or more terms to be indexed, indexing each of the one or more terms in a regular index, the regular index having a plurality of postings lists and each postings list corresponding to a string containing one of the one or more terms;

for each of the one or more terms having a plurality of characters, indexing at least one prefix portion of each term in a prefix index that is separated from the regular index, wherein the regular index is used for regular searches, and wherein the prefix index is used for prefix searches without having to combine a plurality of postings lists of the regular index at the point in time;

receiving a search query having a search term for searching files that contain the search term from a client;

determining whether a search to be performed is a regular search or a prefix search;

if the search is a regular search,

searching in the regular index to identify a plurality of postings lists, each containing the search term, and

returning to the client, a list of item identifiers from the plurality of postings lists obtained from the regular index; and

if the search is a prefix search,

searching in the prefix index to identify a single postings list that exactly matches the search term, and

returning to the client, a list of item identifiers from the single postings list;

wherein the regular index and the prefix index are stored in the same file, and wherein each prefix entry of the prefix index is tagged with a marker indicating that the corresponding prefix entry is part of prefix index.

8. The non-transitory computer-readable storage medium of claim 7, wherein the prefix portion of a term comprises a leading character and at least one adjacent character of the term.

9. The non-transitory computer-readable storage medium of claim 7, wherein each of the terms in the regular index and the prefix index is associated with a postings list having one or more item identifiers identifying one or more files that contain the associated term.

10. The non-transitory computer-readable storage medium of claim 7, wherein the one or more terms to be indexed are extracted from at least one of a content data file and metadata of a-the content data file.

11. The non-transitory computer-readable storage medium of claim 7, wherein the regular index and the prefix index are inverted indexes.

12. The non-transitory computer-readable storage medium of claim 7, wherein the search term for the prefix search is captured and received as a user is typing in a search field.

13. a data processing system comprising:

a processor; and

a memory coupled to the processor for storing instructions, which when executed by the processor, cause the processor to perform a method, the method including in response to one or more terms to be indexed, indexing each of the one or more terms in a regular index, the regular index having a plurality of postings lists and each postings list corresponding to a string containing one of the one or more terms,

for each of the one or more terms having a plurality of characters, indexing at least one prefix portion of each term in a prefix index that is separated from the regular index, wherein the regular index is used for regular searches, and wherein the prefix index is used for prefix searches without having to combine the plurality of postings lists of the regular index at the point in time,

receiving a search query having a search term for searching files that contain the search term from a client,

determining whether a search to be performed is a regular search or a prefix search,

if the search is a regular search,

searching in the regular index to identify a plurality of postings lists, each containing the search term, and

returning to the client, a list of item identifiers from the plurality of postings lists obtained from the regular index, and

if the search is a prefix search,

searching in the prefix index to identify a single postings list that exactly matches the search term, and

returning to the client, a list of item identifiers from the single postings list;

wherein the regular index and the prefix index are stored in the same file, and wherein each prefix entry of the prefix index is tagged with a marker indicating that the corresponding prefix entry is part of prefix index.

14. The system of claim 13, wherein the prefix portion of a term comprises a leading character and at least one adjacent character of the term.

15. The system of claim 13, wherein each of the terms in the regular index and the prefix index is associated with a postings list having one or more items identifiers identifying one or more files that contain the associated term.

16. The system of claim 13, wherein the one or more terms to be indexed are extracted from at least one of a content data file and metadata of the content data file.

17. The system of claim 13, wherein the regular index and the prefix index are inverted indexed.