![]() In other words, the lowest bounding value will be included in each partition. A RIGHT range specifies that the boundary value belongs to the right side of the boundary value interval when interval values are sorted by the database engine in ascending order from left to right.In other words, the highest bounding value will be included within a partition. A LEFT range specifies that the boundary value belongs to the left side of the boundary value interval when interval values are sorted by the database engine in ascending order from left to right.For example, given a table that contains sales order data, you may want to partition the table into 12 (monthly) partitions based on a datetime column such as a sales date.Ī range type (either LEFT or RIGHT), specifies how the boundary values of the partition function will be put into the resulting partitions: ![]() The partition function defines the number of partitions and the partition boundaries that the table will have. ![]() Each value in the partitioning column is an input to the partitioning function, which returns a partition value. Partition functionĪ partition function is a database object that defines how the rows of a table or index are mapped to a set of partitions based on the values of a certain column, called a partitioning column. The following terms are applicable to table and index partitioning. To reduce lock contention by allowing lock escalation to the partition, set the LOCK_ESCALATION option of the ALTER TABLE statement to AUTO. This can reduce lock contention on the table. You can improve performance by enabling lock escalation at the partition level instead of a whole table. See Queries below for further information. For example, the query optimizer can process equi-join queries between two or more partitioned tables faster when the partitioning columns are the same as the columns on which the tables are joined. You may improve query performance, based on the types of queries you frequently run. You may also switch individual partitions out of one table and into an archive table. For example, you can choose to compress data in one or more partitions, rebuild one or more partitions of an index, or truncate data in a single partition. The operations are more efficient because they target only these data subsets, instead of the whole table. ![]() You can perform maintenance or data retention operations on one or more partitions more quickly. For example, an operation such as loading data from an OLTP to an OLAP system takes only seconds, instead of the minutes and hours the operation takes when the data is not partitioned. You can transfer or access subsets of data quickly and efficiently, while maintaining the integrity of a data collection. Partitioning large tables or indexes can have the following manageability and performance benefits. In versions earlier than SQL Server 2012 (11.x), the number of partitions was limited to 1,000 by default. The database engine supports up to 15,000 partitions by default. Learn more in Partitioning tables in dedicated SQL pool. Table partitioning is also available in dedicated SQL pools in Azure Synapse Analytics, with some syntax differences. Partitioned tables and indexes are available in all service tiers of Azure SQL Database and Azure SQL Managed Instance. For a list of features supported by the editions of SQL Server, see Editions and supported features of SQL Server 2016. Prior to SQL Server 2016 (13.x) SP1, partitioned tables and indexes were not available in every edition of SQL Server. The table or index is treated as a single logical entity when queries or updates are performed on the data. All partitions of a single index or table must reside in the same database. The data is partitioned horizontally, so that groups of rows are mapped into individual partitions. When multiple files exist in a filegroup, data is spread across files using the proportional fill algorithm. The data of partitioned tables and indexes is divided into units that may be spread across more than one filegroup in a database or stored in a single filegroup. SQL Server, Azure SQL Database, and Azure SQL Managed Instance support table and index partitioning. Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance
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