System and method for parallel computation of frequency histograms on joined tables
AssigneeInternational Business Machines Corporation
InventorsPeter Bendel, Oliver Draese, Vijayshankar Raman, Knut Stolze
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Abstract
According to one embodiment of the present invention, a method for the parallel computation of frequency histograms in joined tables is provided. The method includes reading data in a table row-by-row from a database system using a coordinator unit and distributing each read row to separate worker units. Each worker unit computes a partial frequency histogram for each column in the table in parallel. The partial histograms from the worker units are then merged and the coordinator unit sends the merged frequency histograms to the worker units.
Claims25
A method comprising:
- reading data in a table row-by-row from a database system using a coordinator unit;
- distributing each read row to separate worker units;
- computing a partial frequency histogram for each column in said table using each worker unit in parallel;
- merging partial histograms from said worker units;
- and
- sending said merged frequency histograms to said worker units using said coordinator unit.
A method comprising:
- reading data in a table row-by-row from a database system using a coordinator unit, said table being at a first join depth;
- distributing each read row to separate worker units;
- computing a partial frequency histogram for each column in said table using each worker in parallel;
- merging partial histograms from said worker units;
- sending said merged frequency histograms to said worker units using said coordinator unit;
- said coordinator unit reading rows from a table at a second join depth and distributing each said second join depth table to one of said worker units;
- and
- said worker units computing frequency histograms for each column in said second join depth table using said merged frequency histograms from said first join depth tables.
A database system comprising:
- a coordinator unit;
- a plurality of worker units;
- a set of tables at a first join depth, each table having columns and rows, wherein said coordinator unit reads data in said tables row-by-row and distributes each row to separate worker units;
- said worker units operating in parallel to compute a partial frequency histogram for each column in said table received from said coordinator unit;
- and
- said coordinator unit merging partial histograms form said worker units and sending said merged frequency histograms to said worker units.
A computer program product for computing frequency histograms, said computer program product comprising:
- a computer usable medium having computer usable program code embodied therewith, said computer usable program code comprising:
- computer usable program code configured to:
- read data in a table row-by-row from a database system using a coordinator unit;
- distribute each read row to separate worker units;
- compute a partial frequency histogram for each column in said table using each worker unit in parallel;
- merge partial histograms from said worker units;
- and
- send said merged frequency histograms to said worker units using said coordinator unit.
Dependencies are inferred from the claim text.