关键词: 嵌套模式, 列存, 分组策略, TPCH, 数据库

Abstract: A hybrid column-row strategy is advanced to speed up the queries on both tree-structured and cascading relational datasets. Existing row and column-based storages are analyzed to motivate the schema-driven design of the hybrid storage. By integrating a special data type in the state-of-art nested schemas, a column-row hybrid scheme is presented to reduce the assembly cost in general column-based storages, while common queries can also be executed on the grouping columns instead of processing on the separate columns or rows. Based on the open-source platform Trevni/Avro, it realizes the scheme and highlights the benefits of the optimized union-based physical design for nested schemas and adapts to NULL values in general cases when hierarchical entities need to be flattened. The experiments are conducted on one billion TPCH records, with three flat tables hierarchically organized for three modified scan-intensive queries. The efficiency of all the involved queries on the proposed schema outperforms the competitors by at least 7X in a general-purpose cluster.

Key words: nested schema, column storage, grouping strategy, TPCH, DBMS