Re: Tables with heavy activity

Sur Thu, 27 Jun 2002 21:06:47 GMT, Daniel Morgan <dmorgan_at_exesolutions.com> a écrit:
> Carlos Alberto wrote:
>
> > Hi,
> >
> > I have 2 very small tables with heavy activity during all the day.
> > Both of them have consistently a lot of INSERT´s and DELETE´s on them.
> > I was wondering
> > about PCTFREE, PCTUSED parameters. I think PCTFREE could be very low,
> > and
> > PCTUSED could be about 50/60, in order to avoid the continuous move of
> > blocks
> > on the free list. I was also wondering about put this tables in
> > memory, is it worth?. What do you think about that?
> >
> > Thanks in advanced,
> > Carlos
>
> If what is happening is only inserts and deletes use 100% of the block:
> Who cares? The only reason to leave room free in a block is for updates.
>
> Daniel Morgan

Another reason to let free space in the blocks would be to avoid hot blocks in the buffer cache :

if your table is small, and accessed in order to insert/update/delete very often, you will get a lot of "buffer busy waits", so you can set a higher pcfree in order to store less rows in each block, therefore reducing the hot spot (then add a few more db_block_lru_latches do spread the load, and the trick is done).

Christian GILBERT
SNPI DTO/SGBD Oracle
01 55 88 41 21 Received on Fri Jun 28 2002 - 07:43:48 CDT