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When tables and indexes become large, managing them can turn out to be a real challenge. While smaller tables are often quick and efficient to query and maintain, the story changes with massive amounts of data. So, how do you deal with large tables and indexes? Welcome to SQL Server Partitioning – a powerful feature that can make your life much easier when handling large corridors of data.
What is SQL Server Partitioning?
SQL Server Partitioning is a feature that allows you to distribute portions of large tables among different filegroups in a database. This division is based on a specified column so that different rows are stored in different places, termed as partitions. Each partition may be stored in a different location on a hard disk or even on separate disks for performance optimization.
SQL Partitioning Syntax
Here’s an example of how to partition a table based on the date column:
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CREATE PARTITION FUNCTION PartitionFunc(DATETIME) AS RANGE LEFT FOR VALUES ('2019-01-01', '2020-01-01', '2021-01-01'); CREATE PARTITION SCHEME PartitionScheme AS PARTITION PartitionFunc TO ([PRIMARY], [PRIMARY], [PRIMARY], [PRIMARY]); |
In the above code, we’ve defined a new partition function named ‘PartitionFunc’ and specified that it applies to ‘DATETIME’ data type. The keyword RANGE LEFT indicates that the boundary values belong to their left partition. The ‘FOR VALUES’ keyword is used to specify the boundary points that create the partitions. In this case, we’ve created four partitions – for data prior to 2019, data for the year 2019, data for the year 2020, and data for 2021 and beyond.
The next step is to create a partition scheme that maps the partitions to filegroups. In this scenario, we’ve used the PRIMARY filegroup for all partitions.
Applying the Partition Scheme:
Partition schemes can be defined during the creation of tables or indexes, or later applied to existing ones. Here’s how you can create a table that uses a partition scheme:
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CREATE TABLE MyTable ( MyDate DATETIME, MyText VARCHAR(MAX) ) ON PartitionScheme (MyDate); |
The above code creates a new table named ‘MyTable’. The table is stored on the partition scheme based on the ‘MyDate’ column values.
Please note that it’s essential to carefully plan and implement partitioning, and it’s consequently vital to thoroughly understand your data before you commence partitioning. Always consider the best practices and assess the potential impact on your SQL Server environment.
Conclusion
SQL Server Partitioning offers an efficient manner to manage large tables and indexes, significantly improving the performance and management of databases with extensive amounts of data. With the correct implementation, it can vastly optimize your SQL server’s efficiency.