Database management system, method and program for supporting the mutation of a composite object without read/write and write/write conflicts

A method for mutating, in response to a query language statement, a composite object in a database managed by a database management system, the method comprising:

• inserting a copy constructor in a parsed representation of the query language statement to create a copy of the composite object when the composite object is being mutated;
• using the copy by a mutator function in the query language statement;
• and
• using an original of the composite object for other functions in the query language statement.

A method of mutating, in response to a query language statement, a composite object in a database managed by a database management system, the method comprising:

• setting a mutation safe status for each parse tree node of the query language statement according to the following:
• a) for each leaf node corresponding to a composite object, setting the mutation safe status to indicate that the node is not safe;
• b) for each non-leaf node, deriving the mutation safe status from an incoming node and from the function itself;
• and
• inserting a copy constructor for a mutated composite object, if the mutation safe status is not safe, and setting the mutation safe status to true for a mutator node of the mutated composite object.

A method of processing a SET statement, the method comprising:

• grouping together update entries based upon a same target being updated;
• generating, by a compiler, a copy of a composite object which is the same target being updated;
• and
• using the generated copy as a common target for mutations caused by the update entries of a same group.

A method for processing a SET statement, the method comprising:

• generating, by a query compiler, a copy (a mutation target) of a common composite object being updated in the statement;
• transforming an update entry of the form
• C..f.sub.1. . . f.sub.n =expression
• into a mutation function call
• f.sub.n (f.sub.n-1 ( . . . (f.sub.1 (C)) . . . ), expression)
• where C is the mutation target generated by the compiler;
• and
• merging all of the mutation function calls for all related update entries together into a nested sequence function invocation, wherein a first argument of the function is returned as a result and a second argument of the function obtains an effect caused by a mutation, to create an accumulated effect for the mutations in the copy of the common composite object.

A method for processing a SET statement, the method comprising:

• generating, by a query compiler, a copy (a mutation target) of a common composite object being updated in the statement;
• grouping together update entries in a sequence of nested function invocations, a function invocation for each attribute being updated, wherein a first argument of the function is returned as a result and a second argument of the function obtains an effect caused by a mutation;
• and
• setting an indicator associated with a parse tree node of the mutation target to indicate that mutation is safe thereby avoiding a copy function being inserted and creating an accumulated effect for the mutations in the copy of the common composite object.

A system for handling a mutation of a composite object in a database managed by a database management system, the system comprising:

• means for inserting a copy constructor in a parsed representation of a query language statement to create a copy of the composite object when the composite object is being mutated;
• means for using the copy by a mutator function in the query language statement;
• and
• means for using an original of the composite object for other functions, if any, in the query language statement.

A system for handling a mutation of a composite object in a database managed by a database management system, the system comprising:

• a query parser having means for setting a mutation safe status for each parse tree node of the query language statement according to the following:
• a) for each leaf node corresponding to a composite object, setting the mutation safe status to indicate that the node is not safe;
• b) for each non-leaf node, deriving the mutation safe status from an incoming node and from the function itself;
• and
• means for inserting a copy constructor for a mutated composite object, if the mutation safe status is not safe, and means for resetting the mutation safe status to true for a mutator node of the mutated composite object.

A database management system having means for processing a SET statement, the system comprising:

• means for grouping together update entries based upon a same target being updated;
• a compiler for generating a copy of a composite object which is the same target being updated;
• and
• means for using the generated copy as a common target for mutations caused by the update entries of a same group;
• and
• means for setting a mutation safe indicator associated with the common target to true to avoid a copy function being inserted for subsequent mutations.

A program, having computer readable program code means on a computer usable medium, having means for handling a mutation of a composite object in a database, the program comprising:

• means for causing an insertion of a copy constructor in a parsed representation of a query language statement to create a copy of the composite object when the composite object is being mutated;
• means for causing a use of the copy by a mutator function in the query language statement;
• and
• means for causing a use of an original of the composite object for other functions in the query language statement.

A program, having computer readable program code means on a computer usable medium, having means for handling a mutation of a composite object in a database, the program comprising:

• means for causing a generation of a copy of the composite object before the composite object is to be mutated;
• means for causing a setting of a mutation safe status, during parsing, for each parse tree node of a query language statement wherein a determination as to where to insert the generated copy in a parsing of the query language statement is determined according to the mutation safe status;
• and
• means for causing a use of the copy by a mutator function in the query language statement.

A program, having computer readable program code means on a computer usable medium, having means for handling a mutation of a composite object in a database, the program comprising:

• means for causing a setting of a mutation safe status for each parse tree node of a query language statement according to the following:
• a) for each leaf node corresponding to a composite object, setting the mutation safe status to indicate that the node is not safe;
• b) for each non-leaf node, deriving the mutation safe status from an incoming node except that constructors and copy constructors are always safe;
• and
• means for causing an insertion of a copy constructor for a mutated composite object, if the mutation safe status is not safe, and causing a setting of the mutation safe status to true for a mutator node of the mutated composite object.

A program, having computer readable program code means on a computer usable medium, having means for processing a SET statement, the program comprising:

• means for causing a generation of a copy (a mutation target) of a common composite object being updated in the statement;
• means for transforming an update entry of the form
• C..f.sub.1. . . f.sub.n =expression
• into a mutation function call
• f.sub.n (f.sub.n-1 ( . . . (f.sub.1 (C)) . . . ), expression)
• where C is the mutation target generated by the compiler;
• and
• means for merging all of the mutation function calls for all related update entries together into a nested sequence function invocation, wherein a first argument of the function is returned as a result and a second argument of the function obtains an effect caused by a mutation, to create an accumulated effect for the mutations in the copy of the common composite object.

A program, having computer readable program code means on a computer usable medium, having means for processing a SET statement, the program comprising:

• means for causing a generation of a copy (a mutation target) of a common composite object being updated in the statement;
• means for causing a grouping together of update entries in a sequence of nested function invocations, a function invocation for each attribute being updated, wherein a first argument of the function is returned as a result and a second argument of the function obtains an effect caused by a mutation;
• and
• means for causing a setting of an indicator associated with a parse tree node of the mutation target to indicate that mutation is safe thereby avoiding a copy function being inserted and creating an accumulated effect for the mutations in the copy of the common composite object.