Database Buffer Cache

Database Buffer cache is one of the most important components of System Global Area (SGA). Database Buffer Cache is the place where data blocks are copied from datafiles to perform SQL operations. Buffer Cache is shared memory structure and it is concurrently accessed by all server processes.

Working of Database buffer Cache

Buffer Cache is organized into two lists

Write List

Write list contains dirty buffers. These are the data blocks which contain modified data and needed to be written to datafiles.

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SQL Processing

When query is submitted to oracle server, various processing steps are performed to execute query. Following main steps are involved in this process.

1- Query Parsing

2- Optimizer determines most efficient way to execute query and generates an execution plan.

3- Finally SQL engine executes query.

In 1st step, SQL server checks syntax of query and outputs error if found.

After parsing of query, optimizer generates execution plan. Execution plan produced by optimizer depends on two main possible goals Continue reading “SQL Processing”

Oracle Database Architecture | Oracle Instance

Oracle Database Architecture consists of following three main structures

1- Storage Structure

2- Memory Structure

3- Process Structure

Two of these constitute in primary storage and one in secondary storage.

When a database is created, database files are installed on secondary storage. These files include Control files, Data files, online redo log files, parameter file and password file. All these files formulate “Storage Structure”. Continue reading “Oracle Database Architecture | Oracle Instance”

Oracle Database

Oracle Corporation is one of the leading IT companies at the moment. Oracle Corporation offers multiple software solution for almost all business areas. List of Products owned by oracle provide us a glint.
List of oracle products
This website will focus on Oracle Database. Oracle RDBMS is undoubtedly the most popular and widely used database. Oracle Database 10g and Oracle Database 11g are the hottest versions at the moment. will make an effort to cover following core and basic topics

  • Database Architecture
  • Backup and Recovery ( OS level and RMAN)
  • Performance and tunning
  • Flash back Features
  • Auditing & Scheduling
  • External tables and SQL Loader

Tasks will be performed using Oracle EM as well as CLI .