When I opened up SSAS I noticed partitions are only defined by Facts
only. What's up with that? How do I set a time-based partition?

Partitioning in AS is for cubes (fact tables). An important attribute for
the partition (particularly in AS2K -- not so much in AS2K5) is the data
slice that is represents. For example, you might have weekly partitions of
your sales fact cube so one partition might have a data slice set for June 1
2004; another June 8 2004; another June 15 2004; etc.
--
Dave Wickert [MSFT]
dwickert (AT) online (DOT) microsoft.com
Program Manager
BI Systems Team
SQL BI Product Unit (Analysis Services)
--
This posting is provided "AS IS" with no warranties, and confers no rights.


<ricocali (AT) hotmail (DOT) com> wrote

Dave,

I know all about partitions from 2000. I'm just blowned away that SSAS
2005 doesn't give you an option to do a time base partition or any
dimension for that matter and there isn't a fricken documentation in
the planet to explain why this is so.

Rico

I am still confused as to what you mean by a "doesn't give you an option to
do a time base partition or any dimension for that matter". If you can
explain, possibly I can translate into what we can do.
--
Dave Wickert [MSFT]
dwickert (AT) online (DOT) microsoft.com
Program Manager
BI Systems Team
SQL BI Product Unit (Analysis Services)
--
This posting is provided "AS IS" with no warranties, and confers no rights.


<ricocali (AT) hotmail (DOT) com> wrote

In AS2K you can create partitions that consist of FY01, FY02, FY03 off
the Time-Dimension. In AS2005 it only allows you to partition off
Facts only.

??? I am sorry but I still don't understand.
must be looking in the wrong place. Partition is basically the same as with
AS2K -- in fact it is slightly easier since you no longer need to set the
data slice.
--
Dave Wickert [MSFT]
dwickert (AT) online (DOT) microsoft.com
Program Manager
BI Systems Team
SQL BI Product Unit (Analysis Services)
--
This posting is provided "AS IS" with no warranties, and confers no rights.


<ricocali (AT) hotmail (DOT) com> wrote

Go to BIDS and double-click any cube on the right hand-side. You will
then see the cube folder you just selected with subfolders. Click the
"Partition" subfolder. If you noticed only has "Fact" slices for your
partion. The dimensions are not part of it.

That is right (I guess in a way).

First, some new terms. AS2K5 has a new object called a "measure group" maps
to a fact table (it has a grain that you specify in the dimension usage
tab). In AS2K days, this is what a cube looked like. And then you joined
physical cubes together into virtual cubes (if needed). In AS2K, cubes are
now more holding places for objects than physical entities. The new physical
entity is the measure group.

Within measure groups are partitions. Each partition contains a portion of
the total fact table. Thus you might have a 2002 partition, 2003 partition,
2004 partition. If you look at the properties of a partition you will see
that it contains a property called a "slice".

What you may be seeing and commenting on is that, by default this is blank.
And thus it looks like dimension members are not being setup for the
partition. In AS2K you had to manually set up the data slice for all
partitions. However, this isn't the case anymore. This is because AS2K5 now
automatically detects what dimension members exist in a partition when the
partition is processed. Thus the system automatically figures out that the
2002 partition only has 2002 data in it (the query binding may say something
like SELECT * FROM <fact table> WHERE Year - 2002 or the table binding may
have a relational table which only contains 2002 data -- or it may load from
a view which is only 2002 data).

However, if you wish to, you can add the data slice. This does two things:
first if you are using MOLAP, the system double checks to ensure that only
data matching that data slice will be loaded into the partition. It
generates an error if it reads data that doesn't match it. The second place
where you will want to specify the data slice is when you are using ROLAP or
proactive caching with a ROLAP phase in it. Since ROLAP doesn't actually
move the underly fact data when it is processed, the system cannot
automatically detect that only 2002 data is in that partition. And thus you
must specify the slice to tell the AS runtime optimizer that a particular
data slice is being used (so it can limit how many partitions are processed
by a query).

Is that clearer? I think at the heart of it partitions are extremely similar
between AS2K and AS2K5 --- although they have different objects that they
are part of (i.e. measure groups in AS2K5; and cubes in AS2K).
--
Dave Wickert [MSFT]
dwickert (AT) online (DOT) microsoft.com
Program Manager
BI Systems Team
SQL BI Product Unit (Analysis Services)
--
This posting is provided "AS IS" with no warranties, and confers no rights.


<ricocali (AT) hotmail (DOT) com> wrote