International Business Machines Corporation

Bing Qing Sun

Xin Yang

Shuo Li

Xiaobo Wang

Ping Liang

Hang Xiao

Ze Yuan Hu

Aspects include a method that includes receiving a structured query language (SQL) database command at a processing device configured to manage a table space of a relational database, the database command including a merge statement. The method also includes identifying a group of target records from the database command, and associating each target record with one of a plurality of portions of the table space, and in response to determining that the group of target records is associated with more than one portion of the table space, sorting the target records into a plurality of sub-groups, each sub-group associated with a different portion of the table space. The method further includes generating a sub-task associated with each sub-group, the sub-task prescribing aspects of performing the merge operation using an associated sub-group respective sub-group, and performing all of the sub-tasks on the memory space in parallel.

Parallel execution of merge operations

A technique relates to determining when to skip a group by clause in a query. A computer checks that a condition is satisfied for a table. The condition is selected from the group consisting of having a unique index on one or more columns of the table or having a function on the one or more columns that makes rows in the GROUP BY clause unique. The group by clause is part of the query on the table. In response to the condition being satisfied, the group by clause associated with the one or more columns is skipped. In response to the condition not being satisfied, the group by clause associated with the one or more columns is executed.

Using a unique index to remove group by based on set analysis

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Beijing, China

Bing Qing Sun