OLAP Servers are just databases which store summary information as
information "cubes" (although "layers" might be a better description since
the data can be multi-dimensional). OLAP servers typically run scripts at
certain times of the day which summarise the companies main operational
databases and store the answers to potential queries (like what is the total
dollar value of sales today ? or what are the sales revenues for each store,
or each product line, or each product line by store, or...you get the
picture).
For example, a retailer like The Warehouse might use an OLAP server to store
the answers to thousands of queries so that any manager can get instant
answers to their questions without having to wait for a mega-powered
database server to process a complex SQL query. With all the answers at your
fingertips, you could also cross-correlate data much easier (using some kind
of decision-cube or cross-tab display), and slice and dice it to your hearts
content.
It also allows you to run queries on historical data that would otherwise
cause your database administrator to have a heart attack. Imagine trying to
run a query on all sales made at The Warehouse for the last five years. The
number of individual transactions would run into the billions. You'd have
time to take your annual vacation while waiting for the result. However, an
OLAP cube already has all the possible answers held in daily, monthly, or
annual groups so the maximum process required for a query spanning five
years would be five annual summary records, or 62 monthly summary records,
or about 1826 daily records (assuming a leap-day or two in there somewhere)
; surely no great load for any database server.
SQL Server is by no means the only option, although is is certainly the
cheapest (the MS Plato OLAP server was free last time I heard), and if you
really "need" this technology you might as well bite the bullet and plan a
migration. Other companies like Cognos sell OLAP servers and a quick search
on the net should give you some options, although I'd expect them to be
kinda expensive.Still, if you have a large amount of data which is already
being summarised for reporting purposes then you could reap serious benefits
from this technology.
Cheers,
Simon.
> Hi all,
>
> Just wondering if anyone can give me any feedback on OLAP services...
>
> We run Interbase here as our main SQL Server DB... just wondering
> what OLAP
> exactly is (seems to be part of or require MS SQL Server), and
> what are the
> alternatives.
>
> Regards
>
> Colin Fraser
>
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