Oracle’s OLTP Table Compression uses a unique compression algorithm specifically designed to work with OLTP applications. The algorithm works by eliminating duplicate values within a database block, even across multiple columns. Compressed blocks contain a structure called a symbol table that maintains compression metadata. When a block is compressed, duplicate values are eliminated by first adding a single copy of the duplicate value to the symbol table. Each duplicate value is then replaced by a short reference to the appropriate entry in the symbol table. Through this design, compressed data is self-contained within the database block as the metadata used to translate compressed data into its original state is stored in the block. Oracle’s approach offers performance benefits by not introducing additional I/O when accessing compressed data.