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A method to optimize nullable checks in translated SQL query at compilation time

IP.com Disclosure Number: IPCOM000246129D
Publication Date: 2016-May-11
Document File: 1 page(s) / 31K

Publishing Venue

The IP.com Prior Art Database

Abstract

This disclosure desribes a method to eliminate null checks in a generated code for a given query at a code generation phase without adding additonal phases.

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A method to optimize nullable checks in translated SQL query at compilation time

A program is disclosed that a code generation eliminates null checks in a generated code for a given query. This elimination does not require additional phases. This disclosure requires only a code generation phase.

This disclosure keeps and updates information on whether a column for a query may have a null value or not. This disclosure can avoid to generate null check code if it can be ensured that a value in a column is always non-null or a result by a computation using a column is always non-null. Under an assumption that a node of a tree for the query corresponds to a value in a column or a result of an operation

with columns, this disclosure can avoid to generate code for a null check that corresponds to the value or the result if it is ensured as non-null during a code generation of the tree on a traverse from leafs to a root of the tree. Thus, this disclosure does not introduce additional phases for this elimination.

For example, this disclosure can ensure the result or value of the node has non-null value as the following cases:
(1): a divide/modulo operation with a dividend is non-null and divisor is not zero
(2): an operation whose input operands with non-null results

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