Sizing datafiles

[lynn814]

I'm creating a database with block size of 16k and datafiles of 2GB each.
I read somewhere that when creating LMT with the 'uniform' allocation option, an additional 64k must be added to the datafile for block header & bitmap information.
In my case how much space should be reserved for the header info and how should the extents be sized?

[SANJAY_G]

Metalink says..

When creating tablespaces with a uniform extent size, it is important to understand that Oracle tries to reserve at least 64 Kbytes per datafile for the metadata blocks, which includes both file space header as well as bitmap header.

[OracleDoc]

Now here's a good question..
When would it be appropriate to use automatic allocation instead of uniform?

[slimdave]

Originally posted by OracleDoc
Now here's a good question..
When would it be appropriate to use automatic allocation instead of uniform?

When you don't know how big each segment is going to be, or when you're dealing with a small amount of data (say less than 2Gb) and it's not worth worrying about.

[slimdave]

Originally posted by lynn814
I'm creating a database with block size of 16k and datafiles of 2GB each.
I read somewhere that when creating LMT with the 'uniform' allocation option, an additional 64k must be added to the datafile for block header & bitmap information.
In my case how much space should be reserved for the header info and how should the extents be sized?

I don't think that this ios going to be a problem for you. People trip up over this when they have very large extent sizes (say > 1% of datafile size) and they find a small amount of unusable space at the end of the data file. for example, with a 64Mb uniform extent size, and a datafile size that is an integer multiple of 64Mb, you would have nearly 64Mb un available because it is 64kb too small to get a whole extent allocated.

Not so in your case ... because your extent size is equal-to-or-less-then 64kb, there will be no wasted space.

[lynn814]

Well the table requires the extent sizing to be 160MB. Won't that result in a lot of unused space?

[slimdave]

Make the datfile size an integer multiple of 160Mb, and add 64kb. How big is the complete table?

[abhaysk]

Originally posted by slimdave
Not so in your case ... because your extent size is equal-to-or-less-then 64kb, there will be no wasted space.

Dave :

I am not sure if I have missed any part of the original poster's post.. But i dont see him mentioning Extent Size .. but i see ur remark "because your extent size is equal-to-or-less-then 64kb"

[slimdave]

Originally posted by abhaysk
Dave :

I am not sure if I have missed any part of the original poster's post.. But i dont see him mentioning Extent Size .. but i see ur remark "because your extent size is equal-to-or-less-then 64kb"

Yes, my mistake ... it was one of those "been awake for 5 minutes" answers.

[lynn814]

The table will grow to 50 -60 GB