| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Usenet -> c.d.o.server -> Re: I am confused re PCTFREE and PCTUSED...
NNOOR escribió:
> I am a little confused. Say that PCTFREE is 20 (default) and
> PCUSED is 40 (default). Does that mean, that any given time
> (assuming updates do not occur at a very high rate, and if
> they do, they do not change the data size significantly), the
> maximum space used in a block is only 40%?---20% is left free
> for updates, and data base will stop inserting rows into the
> block when it reaches 40% used. Am I drawing correct conclusions
> from the statement quoted above?
No. PCTFREE is used to set the percentage that will be kept free in order to allow both updates and block headers groweths. This means that inserts in that block will be allowed till the (100 - PCTFREE)% is reached. Once reached this percentage no more insertions in the block will be allowed untill the PCTUSED is reached, this is, the occupied space falls below pctused. Before this value is reached, the free space allocated in the block can only be used for updating the containing rows in that block. =
So, you can insert, update and delete rows until the data are the (100-pctfree)% of the block. Then, you'll only be able to update and delete rows. When, due to these operations, your data space falls below the pctused, you'll be able to insert rows again.
Hope this help and you understand my horrible English. -- =
Julio Negueruela
DBA Servicio Informático
Universidad de La Rioja - Spain Telf: 941-299179 Fax: 941- 299180
 |
 |