Olap isn't a function of SQL OLAP it is another method of organizing, and aggregating your data to be optomized for reporting queries. OLAP Organizes your data in a hierarchal(sp) Manner of Dimension and Level For example:
a Typical TIme Dimension may have the following structure
TIME
YEAR
QTR
MONTH
DATE
Which would appear in like the following
ALL TIME
2000
Q1-2000
Jan-00
Jan-1 2000
Jan-2 2000
Feb-00
Mar-00
Q2-2000
2001
Dimensions are keyed to Fact Tables in a Star (Flat) or Snowflake(normalized) schema. The Dimension structure allows leaf level values to be aggregated up through the dimension which allows quick reporting at all levels of the dimension.
OLAP is pretty much the opposite of OLTP. Within the OLAP technology arena there are Various types of OLAP formats MOLAP, ROLAP, and HOLAP.
- MOLAP: Multidimensional OLAP. MOLAP format is more
efficient. MOLAP Cubes are stored in a manner that is
disconnected from the relational Data Warehouse.
- ROLAP: Relational OLAP. Does not maintain it's
structure and values seperate from a relational DB
the aggrgate values are actually stored within tables
in a relational DB
- HOLAP: Hybrid OLAP is a combination of MOLAP and ROLAP
Allowing Recent data to be stored in MOLAP format and
historical Data in ROLAP form
Analysis Services is the Microsoft OLAP product it is provided on the SQL Server Install set, but is a seperate Application. Analysis Services can exist without MS SQL and can retrieve it's data from any relational database that has an OLE DB driver.
Has much more information on what OLAP is.
HTH
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