What happens on a database buffer cache?

The Oracle database buffer cache is also referred to as buffer cache. The buffer cache stores copies of data blocks in memory (the SGA). These copies are stored in what is called buffers by Oracle. When a dirty buffer is not used anymore, it is written to disk by the Database Writer background process.

What is the database buffer cache?

In SQL Server, the buffer cache is the memory that allows you to query frequently accessed data quickly. When data is written to or read from a SQL Server database, the buffer manager copies it into the buffer cache (aka the buffer pool).

What is PGA and SGA?

The SGA is a group of shared memory structures, known as SGA components, that contain data and control information for one Oracle Database instance. A PGA is a nonshared memory region that contains data and control information exclusively for use by an Oracle process.

What is read into the database buffer cache from data files?

Execute PL/SQL code. Read data blocks from data files into the database buffer cache (the DBWn background process has the task of writing modified blocks back to disk) Return results in such a way that the application can process the information.

What kind of data does Database Buffer Cache hold?

The database buffer cache holds copies of data blocks read from the data files. The term data block is used to describe a block containing table data, index data, clustered data, and so on. Basically, it is a block that contains

What does the Database Buffer Cache in redo log mean?

LGWR subsequently writes entries from the redo log buffer to the online redo log. The database buffer cache holds copies of data blocks read from the data files. The term data block is used to describe a block containing table data, index data, clustered data, and so on. Basically, it is a block that contains data.

When do you need a block in the buffer cache?

A block in the buffer cache can be in one of three states: Ideally, free blocks are available whenever you need them. However, that probably isn’t the case unless your database is so small that the whole thing can fit in memory. The LRU algorithm works a little differently in the buffer cache than it does in the shared pool.

Where are the dirty buffers in the database?

The database buffer cache is organized in two lists: the write list and the least-recently-used (LRU) list. The write list holds dirty buffers, which contain data that has been modified but has not yet been written to disk. The LRU list holds free buffers, pinned buffers, and dirty buffers that have not yet been moved to the write list.