Patent · US Active

Elimination of common subexpressions in complex database queries

US10901990B1 · kind B1 · utility

12Cited by

6References

20Claims

0Family size

Assignee

Tableau Software, Inc. · US

Inventors

Adrian Vogelsgesang · Munich, DE
Jan Finis · Munich, DE
Manuel Then · Munich, DE

Key dates

Filing date	Jan 31, 2018
Grant date	Jan 26, 2021
Priority date	—
Expiry date	Sep 2, 2039

Classification

Technology area (CPC G)Physics
CPC primaryG06F16/24542
WIPO fieldComputer technology
WIPO sectorElectrical engineering

Abstract

A database engine receives a human-readable database query that includes a plurality of conditional expressions. The database engine parses the database query to build an operator tree that includes a subtree corresponding to each of the conditional expressions. The database engine identifies a subexpression that appears in two or more of the conditional expressions. The subexpression is executed conditionally. The database engine hoists the subexpression outside of the conditional expression so that it is executed unconditionally. The database engine modifies the operator tree to specify computation of a value for the subexpression a first time and to reuse the computed value when the subexpression is subsequently encountered. The database engine executes the modified operator tree to form a result set corresponding to the database query, thereby evaluating the subexpression only a single time for each row of input data and returns the result set.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.