Does MS SQL server support table partitioning by List? - sql-server

Question

I am pretty new to table partitioning technique supported by MS SQL server. I have a huge table that has more than 40 millions of records and want to apply table partitioning to this table. Most of the examples I find about the partition function is to define the partition function as Range LEFT|RIGHT for Values(......), but what I need exactly is to something like following example I found from Oracle web page:
CREATE TABLE q1_sales_by_region
(...,
...,
...,
state varchar2(2))
PARTITION BY LIST (state)
(PARTITION q1_northwest VALUES ('OR', 'WA'),
PARTITION q1_southwest VALUES ('AZ', 'UT', 'NM'),
PARTITION q1_northeast VALUES ('NY', 'VM', 'NJ'),
PARTITION q1_southeast VALUES ('FL', 'GA'),
PARTITION q1_northcentral VALUES ('SD', 'WI'),
PARTITION q1_southcentral VALUES ('OK', 'TX'));
);
The example shows that we can specify a PARTITION BY LIST clause in the CREATE TABLE statement, and the PARTITION clauses specify lists of discrete values that qualify rows to be included in the partition.
My question is does MS SQL server support table partitioning by List as well?

Answer 1

It does not. SQL Server's partitioned tables only support range partitioning.
In this circumstance, you may wish instead to consider using a Partitioned View.
There are a number of restrictions (scroll down slightly from the link anchor) that apply to partitioned views but the key here is that the partitioning is based on CHECK constraints within the underlying tables and one form the CHECK can take is <col> IN (value_list).
However, setting up partitioned views is considerably more "manual" than creating a partitioned table - each table that holds some of the view data has to be individually and explicitly created.

Answer 2

You can achieve this by using ausillary computed persisted column.
Here you can find a complete example:
LIST Partitioning in SQL Server
The idea is to create a computed column based on your list like this:
alter table q1_sales_by_region add calc_field (case when q1_northwest in ('OR', 'WA') then 1...end) PERSISTED
And then partition on this calc_field using standard range partition function

Answer 3

What are you trying to accomplish with partitioning? 40M rows was huge 20 years ago but commonplace nowadays. Index and query tuning is especially important for performance of large tables, although partitioning can improve performance of large scans when the partitioning column is not the leftmost clustered index key column and partitions can be eliminated during query processing.
For improved manageability and control over physical placement on different filegroups, you can use range partitioning with a filegroup per region. For example:
CREATE TABLE q1_sales_by_region
(
--
state char(2)
);
CREATE PARTITION FUNCTION PF_State(char(2)) AS RANGE RIGHT FOR VALUES(
'AZ'
, 'FL'
, 'GA'
, 'NJ'
, 'NM'
, 'NY'
, 'OK'
, 'OR'
, 'SD'
, 'TX'
, 'UT'
, 'VM'
, 'WA'
, 'WI'
);
CREATE PARTITION SCHEME PS_State AS PARTITION PF_State TO(
[PRIMARY] --unused
, q1_southwest --'AZ'
, q1_southeast --'FL'
, q1_southeast --'GA'
, q1_northeast --'NJ'
, q1_southwest --'NM'
, q1_northeast --'NY'
, q1_southcentral --'OK'
, q1_northwest --'OR'
, q1_northcentral --'SD'
, q1_southcentral --'TX'
, q1_southwest --'UT'
, q1_northeast --'VM'
, q1_northwest --'WA'
, q1_northcentral --'WI'
);
You can also add a check constraint if you don't already have a related table to enforce only valid state values:
ALTER TABLE q1_sales_by_region
ADD CONSTRAINT ck_q1_sales_by_region_state
CHECK (state IN('OR', 'WA', 'AZ', 'UT', 'NM','NY', 'VM', 'NJ','FL', 'GA','SD', 'WI','OK', 'TX'));