Fig. 3: Loading blocks into the database buffer cache. © Marek Adar
Fig. 3: Loading blocks into the database buffer cache. © Marek Adar
The database buffer cache stores blocks of data in the database. The smallest unit of the Oracle database that can be read or written is the Oracle database block. Table rows, for example, are stored in the database blocks. If a SQL query is used to search for a record in a table, the table block in which this row is located is loaded into the database buffer cache, but only the row being searched for is displayed.
By loading the entire block, all afghanistan telegram screening data records that are in this block are loaded as well. If the same or another user needs data that is also in this block, the block does not need to be reloaded from the disk system, which increases access speed. By optimally configuring the size of the database buffer cache, all important database transaction data can be kept in the main memory.
So that Oracle can recognize which blocks are needed more than others, the presence of the blocks in the database buffer cache is managed by an LRU (Least Recently Used) algorithm. This means that the blocks that are accessed frequently are kept in main memory longer than those that are only loaded once and are no longer needed. This LRU algorithm then removes blocks that are no longer needed from the database buffer cache to make room for new ones.