Oracle SQL Plus The Definitive Guide- P38:Every day, computer professionals the world over wake up, travel to the office, sit down in front of a computer, and begin another day working with that database called Oracle. Programmers write queries and stored procedures. Database administrators monitor performance, make database changes, and perform other maintenance tasks. Operations people may need to back up or recover a database. | previous page page_337 next page Page 337 that weren t committed. The end result is the same as if you had done a SHUTDOWN IMMEDIATE. Looking at Your Database The SHOW command may be used to review information regarding the current state of your database. Use SHOW SGA to see the information about the size of your System Global Area or SGA. With SHOW PARAMETER you can look at the current settings for the database initialization parameters. SHOW LOGSOURCE and SHOW AUTORECOVERY give you information about archive logging and recovery. Remember that the SHOW command options described in this chapter are new with release of SQL Plus which was shipped with Oracle8i. In previous versions of Oracle these SHOW commands were implemented only in Server Manager. Looking at the SGA The SHOW SGA command may be used to display information regarding the size of the System Global Area. The SGA is shared by all Oracle processes and contains the database buffer cache the redo log buffer shared SQL statements and a number of other items. Here is an example of SHOW SGA being used SQL SHOW SGA Total System Global Area Fixed Size Variable Size Database Buffers Redo Buffers 5508612 bytes 45584 bytes 4529140 bytes 409600 bytes 524288 bytes The values returned by SHOW SGA are as follows Total System Global Area The total maximum size of the SGA. Fixed Size This is the minimum size of the SGA and is the size used when the SGA is first allocated. Variable Size This is the amount by which the SGA may expand. previous page page_337 next page previous page page_338 next page Page 338 Database Buffers The number of bytes allocated for buffering of data blocks from the data files. Oracle tries to keep the most recently used data in memory in case it is needed again. Redo Buffers The number of bytes allocated for buffering of redo log data. The log writer LGWR process reads these buffers and writes the information they contain to the redo log files. For more information about the SGA the .
