The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 13, 2013
Filed:
Jun. 30, 2009
Yu Xu, San Diego, CA (US);
Olli Pekka Kostamaa, Santa Monica, CA (US);
Xin Zhou, Monterey Park, CA (US);
Yu Xu, San Diego, CA (US);
Olli Pekka Kostamaa, Santa Monica, CA (US);
Xin Zhou, Monterey Park, CA (US);
Teradata US, Inc., Dayton, OH (US);
Abstract
A system, method, and computer-readable medium for dynamic detection and management of data skew in parallel join operations are provided. Rows allocated to processing modules involved in a join operation are redistributed among the processing modules by a hash redistribution of the join attributes. Receipt by a processing module of an excessive number of redistributed rows having a skewed value on the join attribute is detected by a processing module which notifies other processing modules of the skewed value. Processing modules then terminate redistribution of rows having a join attribute value matching the skewed value and either store such rows locally or duplicate the rows. The processing module that has received an excessive number of redistributed rows removes rows having a skewed value of the join attribute from a redistribution spool allocated thereto and duplicates the rows to each of the processing modules. The join operation is completed by performing a local join at each processing module and merging the results of the local join operations.