Amber wrote:
Serge Rielau
That's very kind of you. How about instances? Can two instances on
the same physical machine hold individual partitions of a partitioned
database? And if InstanceA holds one partition of a partitioned
database DatabaseA, can it hold another non-partitioned database
DatabaseB, or another partition of another partitioned database
DatabaseC?
There's a great picture of the relationships between instance,database,
etc. in the docs, but i couldn't find it quickly, so:
Here's the structure:
1 Instance has 1..999 partitions.
Each partition may exist on a separate physical machine; however,
you can have multiple partitions on a single machine.
A non-partitioned instance is (effectively) an instance with
only 1 partition.
A database is defined within an instance, and is spread across
*all* of the partitions that make up the instance. Yes, all.
Each instance may have multiple databases.
Inside a database, you have database partition groups (aka
nodegroups), which define logical groups of database partitions.
Tablespaces are defined in a database partition group. Since a
database partition group does not need to include all partitions,
a tablespace can therefore be defined on a subset of the partitions.
Tables are defined in a tablespace.
And there are some client connection considerations. If InstanceA
on physical machine ServerA holds partition1 of partitioned database
DatabaseP, InstanceB on physical machine ServerB holds partition2 of
DatabaseP, InstanceC on physical machine ServerC holds partition3 of
DatabaseP ... , then if I only catalog DatabaseP at InstanceA on a
client workstation, can I get any content of the entire database. And
whether catalog any individual instance I can get the same result?
Your terminology is wrong, but I get what you're asking:
Yes, you can connect to any partition participating in an instance in a
database and access ALL data. From a user perspective, a database spead
over 999 partitions doesn't look any different from a database using
only 1 partition.
Good luck,
Ian