Re: Checkpoint duration

timur.go..._at_gmail.com wrote:
> Checkpoint process updates the file headers of the data files and
> flushes the dirty buffers in cache to data files.
>
> i) Is there any propotional relation between "number of datafiles" and
> time spent to perform a checkpoint ?

Often the time spent updating the file header is minor compared to other checkpoint activity. Logically yes there is a relationship.

The actual times taken will vary considerably depending on your io configurations and whether you support async io etc.

> ii) Is the majority of the time spent to checkpoint caused by "header
> update"(LGWR) or "flushing dirty buffers"(DBWR) ?

In general it depends on the system and varies widely. What do you mean by header update and LGWR?

Log writer also goes first. If there are many dirty buffers in your buffer caches then the time taken to do this flushing will probably dwarf the amount of time required to update the file headers. Received on Sun Nov 26 2006 - 18:28:05 CST