Sap Se

Andreas Amler

Till Merker

Paul Willems

Jonathan Dees

Nico Bohnsack

Oliver Horn

Manuel Mayr

Joerg Fellmann

A method for executing a query may include generating a partition value identifier for a partitioned table. The partitioned table may include a main fragment including a main dictionary storing a first value and a main value identifier corresponding to the first value and a delta fragment including a delta dictionary storing a second value and a delta value identifier corresponding to the second value. The partition value identifier may be set based at least in part on the first value and the second value. The generated partition value identifier and a corresponding one of the main value identifier and the delta value identified may be maintained as part of a mapping. A query to group data stored in the partitioned table may be received. The query may be executed by at least using the mapping.

Partition-local partition value identifier grouping

A method for performing a multi-fragment index scan operation included in a query pipeline of a query accessing a database table may include performing an index scan on a first chunk of a first fragment of the database table and a second chunk of a second fragment of the database table. A first output of the index scan on the first chunk of the first fragment of the database table and a second output of the index scan on the second chunk of the second fragment of the database table may be merged to generate a partial result set for ingestion by a next operation in the query pipeline. The multi-fragment index scan operation may continue with index scans on subsequent chunks of the first fragment and second fragment of the database table. Related systems and computer program products are also provided.

Multi-fragment index scan

Arrangements for a reading scheme for column-oriented databases are provided. A virtual column may be generated by applying a structured query language operation on distinct values in a column of data in a table. Based on applying the structured query language operation, the virtual column may be populated with corresponding precalculated values. The virtual column may be compressed with dictionary-based compression. The compressing may include generating a column of value identifiers, each of the value identifiers representing a distinct value in the column of data. A database query against the compressed virtual column may be received. A result of the database query may be returned by retrieving one or more of the precalculated values from the compressed virtual column.

Calculated dictionary column readers

In an example embodiment, a specialized execution process for a Disk Group-By operator with at least one distinct or ordered aggregation is provided. This specialized execution process involves writing all linked lists to disk (optionally this is performed only if the memory budget is coming close to being surpassed). Initially, a separate disk partition can be created per group, but once a partition becomes too large a new partition for the group is created. A partition is considered too large if it would not be able to be loaded into memory without surpassing the memory budget. As a result, every group can have a list of one or more disk partitions attached to it. The data belonging to each group is sorted using a sorted merge from disk.

Disk group-by with sorted merge

Methods and systems for object-based text searching using group score expressions are provided. A method may include receiving a query including a request to search specified columns of a table for a set of search terms, and a group score filter for use in filtering the table based at least on a group score associated with a plurality of groups of rows of the table, determining the group score for each of a plurality of groups of rows of the table, filtering the table based at least on the group score filter included in the query and the group score determined for each of the plurality of groups of rows of the table, and providing at least one group of rows of the plurality of groups of rows that includes at least the portion of the set of search terms.

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Heidelberg, Germany

Andreas Amler