Unified OLTP/OLAP format across memory tiers

One or more non-transitory storage media storing instructions which, when executed by one or more computing devices, cause:

• generating a compression unit that comprises a plurality of data blocks, wherein the compression unit stores tabular data from a database table in a columnar format;
• wherein the plurality of data blocks includes (1) a primary header block that represents a first set of rows of the tabular data and (2) a secondary header block that represents a second set of rows, of the tabular data, that is different than the first set of rows, wherein the secondary header block and any other second header blocks in the plurality of data blocks allow for an arbitrary number of rows to be represented by the compression unit;
• storing the compression unit in persistent storage.