Mechanism to efficiently index structured data that provides hierarchical access in a relational database system

• US 20030033285A1
• Filed: 09/27/2002
• Published: 02/13/2003
• Est. Priority Date: 02/18/1999
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Sedlar, Eric, Murthy, Ravi, Agarwal, Nipun, Jalali, Neema
• Granted Patent: US 7,366,708 B2
• Time in Patent Office: Days
• US Class Current: 707/1
• CPC Class Codes: G06F 16/284 Relational databases
• CPC Class Codes: Y10S 707/954 Relational
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99939 Privileged access

Abstract

Described is a hierarchical index that captures the hierarchical relationship of a hierarchy emulated by a relational database system. The hierarchical index is implemented, using a database table which contains rows that serve as entries of the hierarchical index. Another table has rows that are associated with nodes in the hierarchy. Each entry in the hierarchal index maps to a row that corresponds to a node in the hierarchy. A node in the hierarchy may be a parent node with one or more child nodes. In this case, the corresponding entry in the hierarchical index contains identifiers which identify other entries in the index, where the other entries correspond to rows associated with child nodes of the parent node.

Claims

1. A computer-readable medium having an index, wherein:

said index indexes a table that includes one or more fields;

said index is arranged and ordered based on key values associated with at least one of said one or more fields; and

said index contains a plurality of index entries, wherein each entry of said index entries;

maps to at least one corresponding row in said table, and

contains first access control data, this is not reflected in said key values, that defines user access privileges to access said at least one corresponding row.

2. The computer-readable medium of claim 1, wherein:

said table contains rows that are associated with nodes in a hierarchy;

second access control data defines user access privileges for accessing the rows; and

said first access control data reflects said user access privileges defined by said second access control data.

3. The computer-readable medium of claim 1, wherein:

said plurality of index entries are associated with nodes in a hierarchy; and

wherein said first access control data indicates that one or more users have user access privileges for traversing one or more nodes of said nodes.

4. A method used for resolving a path name that has a sequence of path elements, comprising the steps of:

accessing a first entry in an index that corresponds to a particular path element from said sequence of path elements; and

determining, based on access control data in the first entry, whether a user may access a first item associated with the particular path element in a particular way.

5. The method of claim 4, wherein:

at least one path element follows said particular path element in said sequence; and

the steps further include attempting to access an entry in said index that corresponds to said at least one path element only if said user may access said first item in said particular way.

6. The method of claim 4, wherein said first item is a row in a table that contains rows the correspond to nodes in a hierarchy.

7. The method of claim 4, wherein:

items correspond to nodes in a hierarchy and said first item corresponds to a particular node in the hierarchy; and

wherein the step of determining whether a user may access a first item includes determining whether the user is permitted to access any descendant node of the particular node.

8. A method of accessing information managed by a database server, comprising the steps of:

receiving at a database server a statement that conforms to a database language supported by the database server, wherein said statement specifies operations that involve a table;

wherein said table contains rows that are associated with a hierarchy described by a hierarchical index;

wherein said statement does not reference said hierarchical index; and

using said hierarchical index to execute said statement.

9. The method of claim 8, wherein:

said database statement specifies a DROP operation for said table; and

the step of using said hierarchical index includes performing said DROP operation on said hierarchical index.

10. The method of claim 8, wherein:

said database statement specifies a TRUNCATE operation for said table; and

the step of using said hierarchical index includes performing said TRUNCATE operation on said hierarchical index.

11. The method of claim 9, wherein the steps further include generating an execution plan to execute said statement, said execution plan including an operator defining an operation that uses said hierarchical index.

12. A computer-readable medium carrying one or more sequences of instructions used for resolving a path name that has a sequence of path elements, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

accessing a first entry in an index that corresponds to a particular path element from said sequence of path elements; and

determining, based on access control data in the first entry, whether a user may access a first item associated with the particular path element in a particular way.

13. The computer-readable medium of claim 12, wherein:

at least one path element follows said particular path element in said sequence; and

the steps further include attempting to access an entry in said index that corresponds to said at least one path element only if said user may access said first item in said particular way.

14. The computer-readable medium of claim 12, wherein said first item is a row in a table that contains rows the correspond to nodes in a hierarchy.

15. The computer-readable medium of claim 12, wherein:

items correspond to nodes in a hierarchy and said first item corresponds to a particular node in the hierarchy; and

wherein the step of determining whether a user may access a first item includes determining whether the user is permitted to access any descendant node of the particular node.

16. A computer-readable medium carrying one or more sequences of instructions used for accessing information managed by a database server, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

receiving at a database server a statement that conforms to a database language supported by the database server, wherein said statement specifies operations that involve a table;

wherein said table contains rows that are associated with a hierarchy described by a hierarchical index;

wherein said statement does not reference said hierarchical index; and

using said hierarchical index to execute said statement.

17. The computer-readable medium of claim 16, wherein:

said database statement specifies a DROP operation for said table; and

the step of using said hierarchical index includes performing said DROP operation on said hierarchical index.

18. The computer-readable medium of claim 16, wherein:

said database statement specifies a TRUNCATE operation for said table; and

the step of using said hierarchical index includes performing said TRUNCATE operation on said hierarchical index.

19. The computer-readable medium of claim 17, wherein the steps further include generating an execution plan to execute said statement, said execution plan including an operator defining an operation that uses said hierarchical index.