公开(公告)号：US10572475B2

公开(公告)日：2020-02-25

申请号：US15713365

申请日：2017-09-22

Applicant: Oracle International Corporation

Inventor： Huagang Li ,  Angela Amor ,  Sankar Subramanian ,  Chun-Chieh Lin ,  Vinita Subramanian

IPC: G06F7/00 ,  G06F17/30 ,  G06F16/2453 ,  G06F16/23 ,  G06F16/2455

Abstract: Techniques are described for leveraging column dictionaries of tables for join, group-by and expression evaluation operations. In an embodiment, a table is stored in one or more data units, each data unit's metadata containing dictionaries for stored columns. Rather than storing unencoded column values, the data units may store columns as column vectors of dictionary-encoded values, in an embodiment. When performing a join operation, a matching of values may be performed on the build-side table using the unencoded, unencoded, values stored in the join-key dictionary(s) of the probe-side table, thus, significantly reducing the number of searching and matching operations. In an embodiment, a group-by operation may be executed by performing partial aggregations based on unique group-by key values as stored in the one or more group-by key dictionaries. For an expression evaluation, only a single evaluation may be performed for each unique combination of expression-key values in a data unit by leveraging the one or more expression-key dictionaries.