Why does the Order of index columns matter?
Indexes aren’t magic; their high-performance capabilities come from the fact that they store data in a predetermined order. If your query can utilize data stored in that order, great! However, if your query wants to filter down on color first, but your index is sorted on bird name, then you’ll be out of luck.
How are rows sorted in a PK index?
With a clustered primary key of (RowNumber, DataDate), the rows are logically sorted first by RowNumber and then by DataDate – so all rows where RowNumber = 1 are logically grouped together, then rows where RowNumber = 2 and so on.
How are the columns in a PK index loaded?
Each one has a RowNumber (bigint) and DataDate (date) column. Data is loaded using SQLBulkImport every night, and no “new” data is ever loaded – its a historical record (SQL Standard, not Enterprise, so no partitioning).
Which is the first key in the index?
When it comes to determining what column should be the first key in your index, you should choose whichever one will be most selective (which one will filter you down to the fewest subset of results) for your particular query.
Is there a nonclustered ColumnStore index in SQL Server?
Beginning with SQL Server 2016 (13.x), you can have a nonclustered columnstore index on a rowstore disk-based table or an in-memory OLTP table. This makes it possible to run the analytics in real-time on a transactional table.
Can a table be created as a ColumnStore index?
If you create a table as a columnstore index, you can easily convert the table back to a rowstore table by dropping the columnstore index. Here is a summary of the options and recommendations.
What are the advantages of clustered columnstore indexes?
1. Enforce primary key and foreign key constraints on a clustered columnstore index. 2. Speed up queries that search for specific values or small ranges of values. 3. Speed up updates and deletes of specific rows. 10x on average plus some additional storage for the NCIs.