Partitioning by year on a datetime2 column in a fact table can be a useful technique for managing large data sets, improving query performance, and reducing maintenance costs. Here are the steps to set up partitioning by year:

1. Define a partition function: A partition function defines the ranges or boundaries for partitioning the data. In this case, you would define a partition function that partitions the data by year. For example, the following code creates a partition function that partitions the data by year:

CREATE PARTITION FUNCTION pfFactTableByYear (datetime2(0))
    AS RANGE RIGHT FOR VALUES
    ('2010-01-01T00:00:00', '2011-01-01T00:00:00', '2012-01-01T00:00:00', '2013-01-01T00:00:00', '2014-01-01T00:00:00', '2015-01-01T00:00:00', '2016-01-01T00:00:00', '2017-01-01T00:00:00', '2018-01-01T00:00:00', '2019-01-01T00:00:00', '2020-01-01T00:00:00')

1. Define a partition scheme: A partition scheme maps the partition function to a set of filegroups. In this case, you would define a partition scheme that maps the partition function to a set of filegroups. For example, the following code creates a partition scheme that maps the partition function to a set of filegroups:

CREATE PARTITION SCHEME psFactTableByYear
    AS PARTITION pfFactTableByYear
    TO (fg2010, fg2011, fg2012, fg2013, fg2014, fg2015, fg2016, fg2017, fg2018, fg2019, fg2020)

1. Create the fact table with partitioning: You would create the fact table with the partition scheme defined in step 2. For example, the following code creates a fact table with partitioning by year:

CREATE TABLE FactTable
    (
        Id INT IDENTITY(1,1),
        DateColumn datetime2(0) NOT NULL,
        ValueColumn decimal(18,2) NOT NULL,
        CONSTRAINT PK_FactTable PRIMARY KEY (Id, DateColumn)
    )
    ON psFactTableByYear(DateColumn)

This creates a fact table with a primary key that includes the partitioning column (DateColumn), and maps the partition scheme to the fact table's data filegroups.

1. Load data into the fact table: Once the fact table is created, you can load data into it using standard INSERT statements.
2. Perform maintenance tasks: As time goes on, new partitions will need to be created to accommodate new data. You can automate this process using partition switching or by running a maintenance script that creates new partitions on a regular basis. You may also want to periodically archive or remove old data to keep the data set manageable.

Note that partitioning by year is just one option for partitioning a fact table, and the partition function and scheme would need to be adjusted accordingly for other partitioning strategies, such as partitioning by month, quarter, or some other time period.