PROCESSING LEFT JOIN OPERATIONS VIA A DATABASE SYSTEM BASED ON FORWARDING INPUT

PROCESSING LEFT JOIN OPERATIONS VIA A DATABASE SYSTEM BASED ON FORWARDING INPUT

A database system is operable to determine a query for execution. The database system can execute a left join operation for the query based on receiving a plurality of left input rows, and forwarding all of the plurality of left input rows are forwarded. It is determined whether any right input rows...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser: Bove, Samuel Peter, Saha, Susmita, Arnold, Jason, Schieferstein, Sarah Kate, Saupe, Ellis Mihalko, Guthmann, Max, Dhuse, Greg R
Format: Patent
Sprache:eng
Schlagworte:
CALCULATING
COMPUTING
COUNTING
ELECTRIC DIGITAL DATA PROCESSING
PHYSICS
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Beschreibung
Zusammenfassung:A database system is operable to determine a query for execution. The database system can execute a left join operation for the query based on receiving a plurality of left input rows, and forwarding all of the plurality of left input rows are forwarded. It is determined whether any right input rows match with each given left input row based on a hash map. When one right input row is identified as matching with the given left input row, a value of right input row is copied and emitted in conjunction with the given left input row. When no right input rows are identified as matching with the given left input row, a null value is emitted in conjunction with the given left input row.