Support For User Defined Functions In A Data Stream Management System

• US 20090106190A1
• Filed: 10/18/2007
• Published: 04/23/2009
• Est. Priority Date: 10/18/2007
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Jain, Namit, Srinivasan, Anand, Mishra, Shailendra Kumar
• Granted Patent: US 8,073,826 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 8/20 Software design

Abstract

A data stream management system (DSMS) is designed to support a new user-defined function, by creating and using at least two structures as follows. A first structure (“metadata entry”) is created in response to a command for creation of the new function, and maps a single instance of a class to the function'"'"'s name. A second structure is created with creation of an operator on receipt of each new continuous query that uses the new function. The second structure (“operator specific data structure”) contains a path to the newly-created instance, which path is obtained by looking up the first structure. Additional second structures are created on receipt of additional continuous queries which use the new function, but all second structures contain the same path. All continuous queries use the same instance. Repeated use of a single instance to compile and execute multiple queries eliminates repeated instantiation of the same function.

Claims

1. A method implemented in a computer of processing a plurality of streams of data, the method comprising:

processing the plurality of streams, to execute thereon a plurality of continuous queries based on a global plan;

during said processing, receiving a command to create a function and identification of a set of instructions to be executed to perform said function;

during said processing, creating in a memory of said computer, an instance of said set of instructions and a first structure comprising a reference to said instance;

during said processing, receiving a new continuous query to be executed using said function;

during said processing, based on said first structure, creating in said memory an operator to invoke the instance, the operator comprising a second structure, the second structure comprising a first field to hold said reference to said instance, and at least one additional field corresponding to at least one argument of said function;

during said processing, modifying the global plan by adding thereto said operator, thereby to obtain a modified plan;

altering said processing, to cause execution of the new continuous query in addition to said plurality of continuous queries, based on the modified plan, thereby to perform said function; and

outputting from said computer, a stream generated based at least partially on processing of said data by executing the new continuous query.

2. The method of claim 1 further comprising:

receiving with said command, identification of a names and a type of said at least one argument.

3. The method of claim 2 wherein:

said identification comprises a name of a class containing said function, and a name of a package containing said class;

the command comprises a name clause containing said identification;

the set of instructions is identified by a predetermined label within said package; and

said function is deterministic.

4. The method of claim 1 wherein:

said first structure further comprises a name of said function;

said first structure further comprises a data type of said argument of said function.

5. The method of claim 1 further comprising:

checking if a data type of said argument received in said new continuous query, matches said a corresponding data type of said argument received in said command.

6. The method of claim 1 wherein:

said function is identified in said new continuous query, in a WHEREIN clause and/or SELECT list.

7. The method of claim 1 wherein:

said second structure further comprises a count of the arguments of said function;

said second structure further comprises a data type of a result to be returned by said function.

8. The method of claim 1 wherein:

said instance of said function is repeatedly invoked, on receipt of each tuple of said data, without re-creating said instance;

said instance of said function is also repeatedly invoked, for each additional query, without re-creating said instance.

9. The method of claim 1 wherein:

said second structure further comprises a second field, and the method further comprises copying into said second field a result returned by said function.

10. A data stream management system that processes streams of data using a plurality of continuous queries, the data stream management system comprising:

a store encoded with a plurality of tuples representing a relation, each tuple being time stamped;

a memory encoded with a query plan currently being used in execution of the continuous queries;

means, coupled to said store, for modifying the global plan in said memory in response receipt of a new continuous query that defines a new function defined by a user, if the global plan comprises an instance of the new function, by using a second operator to invoke the instance of the new function to implement the new continuous query; and

means, coupled to said means for modifying and to said store, for executing an instruction in the second operator, to perform the new function.