Efficient collation element structure for handling large numbers of characters

• US 20020184251A1
• Filed: 05/31/2001
• Published: 12/05/2002
• Est. Priority Date: 05/31/2001
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Ho, Ching-Lan, Yang, Jianping
• Granted Patent: US 6,877,003 B2
• Time in Patent Office: Days
• US Class Current: 707/205
• CPC Class Codes: G06F 2207/025 String search, i.e. pattern matching, e.g. find identical word or best match in a string
• CPC Class Codes: G06F 7/02 Comparing digital values G06F7/06, G06F7/22, G06F7/38 take precedence
• CPC Class Codes: G06F 7/24 Sorting, i.e. extracting data from one or more carriers, rearranging the data in numerical or other ordered sequence, and rerecording the sorted data on the original carrier or on a different carrier or set of carriers sorting methods in generalG06F7/36 takes precedence
• CPC Class Codes: Y10S 707/99934 Query formulation, input preparation, or translation
• CPC Class Codes: Y10S 707/99937 Sorting

Abstract

One embodiment of the present invention provides a system for facilitating use of a collation element that supports a large number of characters. The system operates by receiving the collation element and reading a primary weight value from a primary weight field within the collation element. If the primary weight value falls within a reserved set of values, the system reads an additional portion of the primary weight value from both a secondary weight field and a tertiary weight field within the collation element. On the other hand, if the primary weight value is not within the reserved set of values, the system reads a secondary weight value from the secondary weight field, and also reads a tertiary weight value from the tertiary weight field.

Claims

1. A method for facilitating use of a collation element that supports a large number of characters, comprising:

receiving the collation element;

reading a primary weight value from a primary weight field within the collation element;

if the primary weight value falls within a reserved set of values, reading an additional portion of the primary weight value from a secondary weight field and a tertiary weight field within the collation element; and

if the primary weight value is not within the reserved set of values,

reading a secondary weight value from the secondary weight field within the collation element, and

reading a tertiary weight value from the tertiary weight field within the collation element.

2. The method of claim 1, wherein if the primary weight value falls within a reserved set of values, the method additionally comprises:

setting the secondary weight value to a secondary default value; and

setting the tertiary weight value to a tertiary default value.

3. The method of claim 1, wherein the collation element adheres to a structure specified in Unicode Technical Report No. 10.

4. The method of claim 1,

wherein the primary weight value identifies a character;

wherein the secondary weight value can specify an accent on the character; and

wherein the tertiary weight value can specify case information for the character.

5. The method of claim 1, wherein the collation element is four bytes in size, of which the primary weight field is two bytes, the secondary weight field is one byte and the tertiary weight field is one byte, unless a value in the primary weight field belongs to the reserved set of values, in which case the primary weight field takes up all four bytes of the collation element.

6. The method of claim 5, wherein the reserved set of values for the primary weight value includes hexidecimal values 0xFFF0-0xFFFF.

7. The method of claim 1, wherein the collation element is taken from a collation weight table that is used to map characters to collation weights in order to establish an ordering between strings of characters.

8. The method of claim 7, further comprising constructing a sorting key for a string by:

reading each character in the string;

looking up a corresponding collation element for each character from the collation weight table; and

adding the corresponding collation element for each character to the sorting key.

9. The method of claim 8,

wherein the sorting key is associated with a record within a database;

and

wherein the sorting key is used to construct a linguistic index for the database.

10. A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for facilitating use of a collation element that supports a large number of characters, the method comprising:

receiving the collation element;

reading a primary weight value from a primary weight field within the collation element;

if the primary weight value falls within a reserved set of values, reading an additional portion of the primary weight value from a secondary weight field and a tertiary weight field within the collation element; and

if the primary weight value is not within the reserved set of values,

reading a secondary weight value from the secondary weight field within the collation element, and

reading a tertiary weight value from the tertiary weight field within the collation element.

11. The computer-readable storage medium of claim 10, wherein if the primary weight value falls within a reserved set of values, the method additionally comprises:

setting the secondary weight value to a secondary default value; and

setting the tertiary weight value to a tertiary default value.

12. The computer-readable storage medium of claim 10, wherein the collation element adheres to a structure specified in Unicode Technical Report No. 10.

13. The computer-readable storage medium of claim 10,

wherein the primary weight value identifies a character;

wherein the secondary weight value can specify an accent on the character; and

wherein the tertiary weight value can specify case information for the character.

14. The computer-readable storage medium of claim 10, wherein the collation element is four bytes in size, of which the primary weight field is two bytes, the secondary weight field is one byte and the tertiary weight field is one byte, unless a value in the primary weight field belongs to the reserved set of values, in which case the primary weight field takes up all four bytes of the collation element.

15. The computer-readable storage medium of claim 14, wherein the reserved set of values for the primary weight value includes hexidecimal values 0xFFF0-0xFFFF.

16. The computer-readable storage medium of claim 10, wherein the collation element is taken from a collation weight table that is used to map characters to collation weights in order to establish an ordering between strings of characters.

17. The computer-readable storage medium of claim 16, wherein the method further comprises constructing a sorting key for a string by:

reading each character in the string;

looking up a corresponding collation element for each character from the collation weight table; and

adding the corresponding collation element for each character to the sorting key.

18. The computer-readable storage medium of claim 17,

wherein the sorting key is associated with a record within a database;

and

wherein the sorting key is used to construct a linguistic index for the database.

20. The apparatus of claim 19, wherein if the primary weight value falls within the reserved set of values, the assignment mechanism is configured to:

set the secondary weight value to a secondary default value; and

to

set the tertiary weight value to a tertiary default value.

21. The apparatus of claim 19, wherein the collation element adheres to a structure specified in Unicode Technical Report No. 10.

22. The apparatus of claim 19,

wherein the primary weight value identifies a character;

wherein the secondary weight value can specify an accent on the character; and

wherein the tertiary weight value can specify case information for the character.

23. The apparatus of claim 19, wherein the collation element is four bytes in size, of which the primary weight field is two bytes, the secondary weight field is one byte and the tertiary weight field is one byte, unless a value in the primary weight field belongs to the reserved set of values, in which case the primary weight field takes up all four bytes of the collation element.

24. The apparatus of claim 23, wherein the reserved set of values for the primary weight value includes hexidecimal values 0xFFF0-0xFFFF.

25. The apparatus of claim 19, wherein the collation element is taken from a collation weight table that is used to map characters to collation weights in order to establish an ordering between strings of characters.

26. The apparatus of claim 25, further comprising a key construction mechanism for constructing a sorting key for a string, wherein the key construction mechanism is configured to:

read each character in the string;

lookup a corresponding collation element for each character from the collation weight table; and

to

add the corresponding collation element for each character to the sorting key.

27. The apparatus of claim 26,

wherein the sorting key is associated with a record within a database;

and

wherein the sorting key is used to construct a linguistic index for the database.

19. An apparatus that facilitates use of a collation element that supports a large number of characters, comprising:

an assignment mechanism that is configured to read a primary weight value from a primary weight field within the collation element;

wherein if the primary weight value falls within a reserved set of values, the assignment mechanism is configured to read an additional portion of the primary weight value from a secondary weight field and a tertiary weight field within the collation element; and

wherein if the primary weight value is not within the reserved set of values, the assignment mechanism is configured to,

read a secondary weight value from the secondary weight field within the collation element, and to

read a tertiary weight value from the tertiary weight field within the collation element.