If you are having trouble getting your head around the basics of Oracles Architecture, this video does a good job of simplifying things and making it easy to remember by breaking it down and describing it via everyday examples. You can skip to around 2:30 for the real start of the video. Notes; Datafiles – …
It is possible to use operating system commands such as rm on linux to delete RMAN backup files and generally recover from it, however you are far better using built in RMAN commands to do this. $ rman target / NOCATALOG First, check that all backup files are still available. This will show whether files …
Great webinar on Oracle 12c plugable databases. Skip to 8 minutes for the start of the actual presentation.
[embedplusvideo height=”356″ width=”584″ standard=”http://www.youtube.com/v/L_2TfSHotsY?fs=1″ vars=”ytid=L_2TfSHotsY&width=584&height=356&start=&stop=&rs=w&hd=0&autoplay=0&react=1&chapters=¬es=” id=”ep6822″ /] Watch the rest of this series: Part 1 Part 2 Part 4 Notes: Initilisation params for the Buffer cache: db_cache_size db_block_size It is very helpfull if the buffer block size is a multiple of your operating system block size. The Buffer cache is controled with a Least Recently Used …
[embedplusvideo height=”328″ width=”584″ standard=”http://www.youtube.com/v/nNGLyWIPPTQ?fs=1″ vars=”ytid=nNGLyWIPPTQ&width=584&height=328&start=&stop=&rs=w&hd=0&autoplay=0&react=1&chapters=¬es=” id=”ep8443″ /] Watch the earlier parts first: Part 1 Part 2 Part 3 Notes: Oracle Processes Dbwr Database Writer Writes from the SGA to the data files Does deffered writes like a hotel room clerk kicks blocks out to disk when new data needs free blocks Lgwr Log …
[embedplusvideo height=”328″ width=”584″ standard=”http://www.youtube.com/v/wmc9uxNW99E?fs=1″ vars=”ytid=wmc9uxNW99E&width=584&height=328&start=&stop=&rs=w&hd=0&autoplay=0&react=1&chapters=¬es=” id=”ep5503″ /] Check out part 1 first. Notes: Online Redo Logs Contains Redo and Undo info DML Inserts/Deletes DDL – Create alter drop Commits Need at least 2 files/groups Should be multiplexed each on different devices and controlers When each file fils, next one is started and old one is archived (if …
[embedplusvideo height=”328″ width=”584″ standard=”http://www.youtube.com/v/addFo5FMzkg?fs=1″ vars=”ytid=addFo5FMzkg&width=584&height=328&start=&stop=&rs=w&hd=0&autoplay=0&react=1&chapters=¬es=” id=”ep3446″ /] There are 3 essential elements of any database system Datafiles – storage Memory – in oracle its the SGA Processes – To operate on the data files and memory Storage Datafiles Contains data Tables Indexes Undo segments (used to be rollback segments) Temporary files Oracle is easy as DIRT …
When data is changed in the oracle database, the information needed to undo the changes is recorded so that the change can be undone (Rolled back). The record is basically just the original information. Information is recorded in rollback segments and the undo tablespaces. This information is also used to provide read consistency which allows long running transactions …
When a redo log file fills up it switches to the next file. This is called a log switch. The log switch always causes a checkpoint to occur. This flushes all dirty buffers from the log cache. (writes modified data to disk) If archiving is on, the old log file id archived. The new log …
One of the most important ideas in Oracle is that your data is safe. It is protected from corruption and also from system crashes. One of the most important ways that it does this is through the Redo logs. A Redo log record is written to describe the changes every time some data is changed …