Oracle Architecture Part 4

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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 Writer

  • writes info to the current group of redo logs

Smon

System monitor

  • very important process
  • performs instance recovery
  • cleans up after sorts

 

Pmon

Process monitor

  • Monitors Processes
  • detects – deadlock detected for example

 

Ckpt

Checkpoint process

one big reason for checkpoints is that commonly accessed
data may never get written out to disk. A checkpoint forces
this to get written.

Oracle Instance

– is the SGA and background processes

 

Oracle database and the Oracle instance combined is called the Oracle Server.

You can have multiple instances associated with the same database, this is called RAC.

Dedicated server process connects through the PGA.

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