What is the relations between extent and datafile ?

[Striker99]

All,

Could anyone please tell me what is the relations between a extent and a datafile ? What are the implications of extent size on datafile ?

Thanks,
striker99

 

[jee]

An extent is a contiguous area of a data file. When a data file is first created, it has one extent of the size you specified for the original file size. If the data file has to expand, another extent is created, which is probably not contiguous with the original file. Having multiple extents in a data file can negatively impact performance. The extent size is the amount of space on the disk that will be allocated when a new extent is created - so each time your datafile extends its size will increase by the extent size.

 

[OraCool]

Hi Striker99

A 'datafile' is an O/S file you add to a tablespace.
An 'extent' is the size of each chunk (initial/next) you allocate in your create table command. The first extent is defined by the 'initial' parameter in the create table command, the second extent added to the table is defined by the 'next' parameter, thereafter Oracle allocates last-extent-added*pctincrease for every other extent added to the table.

Need more info?
Regards

 

[Striker99]

Thanks guys,

Could you tell me how do i make decision on what should be by initial/next parameters. Say if my file size is 2G's ?

Thanks in advance,
striker99