Re: Fragments ?

[Mikael Ronström]

Hi Florian,


Florian Ri�ner wrote:
> Hello,
>
> some questions about usage of fragmentation:
>
> 1. is it possible to configure where a fragment
> may is stored on disk?
> e.g. am I able to configure that fragment 1 is
> stored on localdisk sda1 and fragment 2 is stored
> on localdisk sdb1
>

In theory it is possible but only by some intricate file handling.

Data files of Table with Id = 4 and Fragment 0 are stored in
root_of_ndb_filesystem/D5/DBTUP/T4/F0
so if you can create those directories before creating the table
on the proper disk then the answer is yes.

So in practice answer is no.

Work is currently ongoing on creating partitions (fragments) when creating
tables and then there will be some syntax to assist in mapping the
fragments to TABLESPACES.

> 2. what happens if another storage-space is added
> to a node?
> e.g. sdc1 is added to a node; a new fragment 3 is
> configured to store on this disk
>

Fragments are created when table is created there is currently no method
for adding fragments to a table (this feature might appear in future versions)
TABLESPACE's will be possible to add new ones when this feature appears.

> 2a. what happens to this node? will the data
> become reorganized and spread over all 3
> fragments?
>

N/A

> 2b. what happens to cluster if fragmentation is
> configured different on different nodes?
> e.g. node 2 and node 3 are configured with
> fragment 1 and 2; node 1 is configured with
> frament 1,2 and 3
>

Fragmentation is currently automatic. In the ongoing work on
partition it will be possible to map partitions to node groups.

> is there any additional spec to "MySQL Cluster
> Administrator Guide" ?
> i'm looking for some information particularly
> concerning the fragmentation problem
>

Look in the on-line MySQL Reference Manual.
There is one chapter on MySQL Cluster there.
Not very much more on the fragmentation problem
however.

If you have specific questions and/or requirements it would be
interesting to hear them since I am designing partitioning
support right now.

>
> Sincerely Yours,
> F. Rißner
>
> P.S.: any experiences with an API-node on
> Windows-Server and DB-Nodes on linux-servers?

Should be ok as long as the endian is the same, thus if all machines are
x86's it should be ok. One has to think about file names though.

Rgrds Mikael