International Business Machines Corporation

Entit Software LLC

James L Finnerty

Venkannababu Tammisetti

Paul-John A To

Venkatesh S Gopal

Stephen Gregory Walkauskas

Jaimin M Dave

A method for managing database nodes includes determining that a data segment is on a failed node. The data segment is referenced by an operation of a query plan. The method includes selecting a victim node based on a segmentation ring, a buddy node for the data segment, a plurality of remaining operational nodes, and a predetermined selection parameter. The method includes generating a query plan such that the victim node performs double duty for operations accessing the data segment from a buddy projection on the victim node, and operations accessing a data segment for a primary projection of the victim node.

Managing database nodes

Provided are techniques for estimating most frequent values. A sample of values made up of rows is received from each of multiple nodes. The sample of values from each of the multiple nodes are aggregated to generate a sample table storing the rows. A descending list of most frequent values and associated frequencies is obtained using the sample table. Most frequent values are pruned from the descending list whose associated frequencies are below a minimum absolute frequency. The remaining most frequent values are extrapolated to reflect a data set.

Estimating most frequent values for a data set

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Concord, MA, United States of America

James L Finnerty