Hewlett-Packard Development Company, L.p.

Entit Software LLC

Andrew Allison Lamb

Lakshmikant Shrinivas

Shilpa Lawande

Mitch Cherniack

Nga Tran

Charles Edward Bear

Hongmin Fan

Chuck Bear

Methods, systems and program products for query optimization using sideways information passing. In one implementation, a join clause in a query is identified that specifies an outer table of tuples to be joined with an inner table, the outer table having one or more attributes, and each of the attributes of the outer table having values stored in an attribute file that is distinct from attribute files in which the values of other attributes are stored. A plan for the query is created which, when executed, causes selection of a subset of tuples of the outer table to serve as input to the join clause in place of the outer table based on one or more predicates applied to the inner table.

Sideways information passing

According to an example, in a method for executing a user-defined function on a plurality of database tuples, the user-defined function and an analysis function may be obtained. In addition, the plurality of database tuples may be divided into parts by a processor, the processor may be caused to execute the analysis function on each of the parts, and the processor may be caused to execute the user-defined function on at least one of the parts for which the analysis function returned a true predicate.

Executing user-defined function on a plurality of database tuples

Computer programs encoded on a computer storage medium provide for a modular query optimizer. In one aspect, a computer program product includes selecting one or more projections from a set of projections for each table in a database query wherein each of the selected projections for the table has leads to an estimated lower execution cost for the query as compared to non-selected projections; generating join orders for the query based on data distribution of one or more of the selected projections among sites in a computer network wherein the join orders reflect different combinations of data distribution operations applied to the output of one or more of the query's joins; and selecting a join order from the join orders based on evaluation of the join orders using a cost model.

Modular query optimizer

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for modular query optimizer. In one aspect, a method includes selecting one or more projections from a set of projections for each table in a database query wherein each of the selected projections for the table has leads to an estimated lower execution cost for the query as compared to non-selected projections; generating join orders for the query based on data distribution of one or more of the selected projections among sites in a computer network wherein the join orders reflect different combinations of data distribution operations applied to the output of one or more of the query's joins; and selecting a join order from the join orders based on evaluation of the join orders using a cost model.

Methods, program products and systems for determining, for a database query that does not represent a snowflake schema, a graph comprising vertices each representing a table joined in the query, a directed edge between each pair of vertices of which a first vertex represents a first table and a second vertex represents a second table that is joined in the query with the first table, each of the edges representing one of an outer join and an inner join. Further determining, for the graph, a directed spanning tree that represents an ordering of joins in the query and includes all outer join edges in the graph.

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Andrew Allison Lamb