The Shared Pool environment contains both fixed and variable structures. The Fixed structures remain relatively the same size, whereas the variable structures grow and shrink based on user and program requirements.
Used To Store
Most Recently Executed SQL Statements
Most Recently used Data definitions
It Consists of two Key performance - related memory structures
Library Cache & Data Dictionary Cache
Shared Pool is sized by SHARED_POOL_SIZE
It is area in memory that is used by a Single Oracle User Process.
Data segment are the physical areas within a database block in which the data associated with tables and clusters are stored.
Due to insufficient Shared SQL pool size.
Monitor the ratio of the reloads takes place while executing SQL statements. If the ratio is greater than 1 then increase the SHARED_POOL_SIZE.
LOGICAL & PHYSICAL ARCHITECTURE OF DATABASE.
Database buffers are cache in the SGA used to hold the data blocks that are read from the data segments in the database such as tables, indexes and clusters DB_BLOCK_BUFFERS parameter in INIT.ORA decides the size.