【正文】
when: ? There are many dirty buffers ? There are few free buffers ? Timeout occurs ? Checkpoint occurs SGA Redo log buffer Data buffer cache Shared pool Database Redo log files Control files Data files DBW0 E26 Copyright 169。 Oracle Corporation, 2023. All rights reserved. SMON: System Monitor ? Automatically recovers the instance: – Rolls forward changes in the redo logs – Opens the database for user access – Rolls back unmitted transactions ? Coalesces free space ? Deallocates temporary segments E27 Copyright 169。 Oracle Corporation, 2023. All rights reserved. PMON: Process Monitor Cleans up after failed processes by: ? Rolling back the transaction ? Releasing locks ? Releasing other resources E28 Copyright 169。 Oracle Corporation, 2023. All rights reserved. Summary In this appendix, you should have learned how to: ? Identify database files: data files, control files, online redo logs ? Describe SGA memory structures: DB buffer cache, shared SQL pool, and redo log buffer ? Explain primary background processes: DBW0, LGWR, CKPT, PMON, SMON, and ARC0 ? List SQL processing steps: parse, execute, fetch E30 Copyright 169。 Oracle Corporation, 2023. All rights reserved. Hidden Slide E31 Copyright 169。 Oracle Corporation, 2023. All rights reserved. 演講完畢,謝謝觀看!