Lob query performance via automatic inference of locator-less lob by value semantics

A computer program product embodied on a non-transitory computer readable medium, the computer readable medium having stored thereon a sequence of instructions which, when executed by a processor causes the processor to execute a method for identifying locator-less LOB by value semantics included in a statement directed to data stored as an inline LOB in a relational database, the method comprising:

• receiving a statement directed to a table stored in the relational database;
• parsing at least a portion of the statement into a query tree comprising a plurality of branches, a branch of the plurality of branches of the query tree corresponding to a clause of the statement;
• for one or more branches of the query tree, identifying a respective inline LOB column referenced by the statement;
• determining whether the inline LOB column is included in an expression having a value-based return type based at least in part on a set of semantics of the expression;
• generating an execution plan to execute the statement, the execution plan comprising an indication as to whether the inline LOB column is included in the expression having the value-based return type;
• and
• executing the statement based at least in part on the execution plan, wherein a LOB locator is not generated when the inline LOB column is included in the expression having the value-based return type and the LOB locator is generated when the inline LOB column is not included in the expression having the value-based return type.

A computer system to implement a method for identifying locator-less LOB by value semantics included in a statement directed to data stored as an inline LOB in a relational database, the system comprising:

• a processor;
• a memory for holding programmable code;
• and
• wherein the programmable code includes instructions for:
• receiving a statement directed to a table stored in the relational database;
• parsing at least a portion of the statement into a query tree comprising a plurality of branches, a branch of the plurality of branches of the query tree corresponding to a clause of the statement;
• for one or more branches of the query tree, identifying a respective inline LOB column referenced by the statement;
• determining whether the inline LOB column is included in an expression having a value-based return type based at least in part on a set of semantics of the expression;
• generating an execution plan to execute the statement, the execution plan comprising an indication as to whether the inline LOB column is included in the expression having the value-based return type;
• and
• executing the statement based at least in part on the execution plan, wherein a LOB locator is not generated when the inline LOB column is included in the expression having the value-based return type and the LOB locator is generated when the inline LOB column is not included in the expression having the value-based return type.