OceanBase Database stores data in macroblocks. Each table can contain multiple macroblocks, and each macroblock occupies 2 MB of space. A macroblock contains one or more microblocks, and each microblock stores one or more rows.
Table organization
Each table in OceanBase Database has a storage key. Storage keys of a table without a primary key are the partitioning key and an automatically generated invisible auto-increment column. The storage key of a table with a primary key is the user-specified primary key. OceanBase Database uses the clustered index table model to organize tables. Data is stored in tables based on the order of their storage keys. Data rows are inserted into tables based on the order of their storage keys.
The same column order applies to all rows in a table. OceanBase Database stores data in a table in the column order that is generated when the table is initially created. New columns are added to the table as the last data columns.
Row storage
Rows are stored in microblocks. In most cases, all columns of a row are stored together. If a table contains large object (LOB) columns, the size of these columns may exceed that of a macroblock. In this case, the extra data spills over to other macroblocks.
Columnar storage
Columnar storage is a database storage method that stores data based on columns. In columnar mode, the data of each column is stored as an independent SSTable, and all columns' SSTables are combined into a virtual SSTable, serving as users' columnar baseline data. This method can effectively improve query performance and reduce storage space consumption.
ROWID
OceanBase Database stores only clustered index tables. A ROWID actually contains the storage key column of a table.
Null value storage
OceanBase Database stores null values and uses one byte as a marker to indicate whether the value in a column is null.