db block get is a buffer retrieval mode.
It's also know as current mode get.
In this mode, the block is retrieved in the buffer cache.
The block is then known as a CURRENT block.
You will see these most frequently during modification statement, which must update only the latest copy of the block.
For example, if an uncommitted transaction has updated two rows in a block, then a current mode get retrieves the block with these uncommitted rows.
In a statistics form, the statistic “db_block_gets” gives the Number of times a CURRENT block was requested
- Oracle® Database Reference 11g Release 2 (11.2) - Statistics Description VSESSTAT and VSYSSTAT