Query execution on compressed in-memory data

A method of query execution on compressed in-memory data, comprising:

• receiving, at a processor of an instance of a distributed in-memory database, a query for data from a table stored in the distributed in-memory database as compressed table data;
• obtaining results data responsive to the query from the table by:
• subsequent to receiving the query, allocating memory for decompressing the compressed table data;
• obtaining uncompressed table data by decompressing the compressed table data into the allocated memory based on a database schema of the distributed in-memory database by decompressing the compressed table data in response to a determination that the database schema indicates that the compressed table data corresponds to a fact table, wherein, obtaining the uncompressed table data includes decompressing at least a subset of the compressed table data into a first temporary buffer of the allocated memory;
• and
• obtaining the results data from the uncompressed table data, wherein obtaining the results data includes accessing the first temporary buffer;
• and
• in response to obtaining the results data, deallocating the allocated memory;
• and
• outputting the results data for presentation to a user.

An apparatus for compressing table data for query execution on compressed in-memory data, comprising:

• a processor of an instance of a distributed in-memory database configured to:
• receive, at the instance, a table, wherein the table comprises a plurality of columns and a set of rows;
• determine a table type of the table according to a database schema of the distributed in-memory database;
• responsive to the table type determined to be a fact table, compress the table to generate compressed table data, wherein the processor is configured to compress the table by:
• dividing the sets of rows into proper subsets of rows;
• determining a data type for each column of the plurality of columns;
• and
• for each column of the plurality of columns, independently compressing rows of the proper subsets of rows sharing the column independently from compressing rows of the proper subsets of rows sharing remaining columns of the plurality of columns, a compression technique used for the compressing based on the data type of the column;
• and
• store the compressed table data as the compressed in-memory data.