Updating xml column sql server
, groups and stores data for each column and then joins all the columns to complete the whole index.
For example, consider a fact table F1 with dimension key columns dk1 and dk2. Instead of calculating M over column dk1 every time that a query referring to M(dk1) is run, a summary table F2(dk1, M) can be created and used so the result can be pre-computed and the query can execute faster.
For some types of queries, the SQL Server query processor can take advantage of the columnstore layout to significantly improve query execution times.
The explosive growth of data warehousing, decision support and BI applications has generated an urgency to read and process very large data sets quickly and accurately into useful information and knowledge.
Columnstore indexes also enable queries to compute the results quickly so that pre-computation is not required.
Typical data warehousing workloads involve summarizing large amounts of data.
The techniques typically used in data warehousing and decision support systems to improve performance are pre-computed summary tables, indexed views, OLAP cubes, and so on.