Kategori: SQL Server

Clustered Columnstore Indexes – Enforcing Uniqueness and Creating Nonclustered Indexes We have seen that once a table has been physically implemented as a clustered columnstore index, further indexes are not supported. We shall now take a look at how to circumvent this limitation, albeit at the cost, perhaps substantial, of additional hard drive space. While […]

Is it Better or Worse? What is Cardinality Estimation A fancy-sounding phrase, ”cardinality estimation” basically means ”guessing how many”. The ability of the query optimizer to select a superior query plan from among many possibilities requires the estimation of how many rows will be extracted from the participating tables and how these rows will be […]

SQL Server Columnstore Indexes Columnstore indexes were introduced into SQL Server in 2012, but in a sense the columnstore index is older than that, since the fundamental structure was first used for the tabular storage model of Power Pivot (and then used in the Analysis Services tabular model). In SQL Server 2012, however, columnstore indexes were […]

James X. from Learning Tree’s Course 535 Developing High Performance SQL Server Databases asked a question (during coffee break) that wasn’t related to performance, but was important nonetheless. ”Is it true that someone can circumvent a lot of SQL Server’s security by simply restoring a database backup to a different machine where he or she […]

In the previous installment, we looked at the numerous options for declaring a cursor. All that remains is the easy part: fetching data from a cursor. To do this, we shall have to declare variables for each of the columns of the cursor. For purposes of clarity and ease of understanding, I see no reason […]