Re: Does a commit cause a checkpoint?

Peter wrote:

> Does a commit cause a checkpoint?
>
> A checkpoint causes the SCN to increment. A logswitch causes a
> checkpoint and threrefore a SCN incremental change.
> What I am confused about is whether a commit causes a checkpoint and
> therefoe a SCN increment.
>

From the "Oracle9i Database Administrator's Guide, Release 2 (9.2), Part Number A96521-01" at
http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96521/onlineredo.htm#ADMIN007 in Chapter 7, "Managing the Online Redo Log", in section titled "Online Redo Log Contents",

the second paragraph reads:

>>>>>>>

Redo records are buffered in a circular fashion in the redo log buffer of the SGA (see "How Oracle Writes to the Online Redo Log") and are written to one of the online redo log files by the Oracle background process Log Writer (LGWR). Whenever a transaction is committed, LGWR writes the transaction's redo records from the redo log buffer of the SGA to an online redo log file, and a system change number (SCN) is assigned to identify the redo records for each committed transaction. Only when all redo records associated with a given transaction are safely on disk in the online logs is the user process notified that the transaction has been committed.
<<<<<<<

Please note the sentance starting with "Whenever a transaction is committed,"

(I'm still wondering what is your documentation source - whatever it is seems to be leaving huge gaps in your understanding)

/Hans

>
> Thanks
Received on Wed Jun 18 2003 - 19:41:45 CDT