xVelocity

xVelocity xVelocity

Columnstore Rowstore

Data grouped & stored one column at a time Data grouped and stored by row

Only the columns needed for a given query must be

readRead entire row then filter result

Natively compressed Manually compressed

Columnar data streamed in batches Native I/O stream

No key columns Key columns (limit of 16)

Supports partitioning Supports partitioning

Batch-mode optimization Bitmap indexes, bitmap filters

http://msdn.microsoft.com/en-US/library/gg492088(v=sql.120).aspx

Pros Cons

On average, 5-100(!) times query performance versus

rowstore for large table queries

Limit of ONE columnstore index on a table (cannot

combine clustered and non-clustered CI)

Efficient storage and retrieval - On average, 7-12 times

compression versus rowstore

Clustered indexes do not support declarative referential

integrity (i.e. key columns and references)

Simplicity – easy to create, easy to manageNonclustered indexes do not support updates of any

kind (must drop & recreate OR use partition switching)

Optimized for VLDB/DSS/EDW/ODSDoes not support all data types, replication, change

tracking, filestream, CDC, page/row compression

DEMO

SQL Server 2014 Columnstore Indexes Reference:

http://msdn.microsoft.com/en-us/library/gg492088(v=sql.120).aspx

CREATE COLUMNSTORE INDEX (T-SQL Reference):

http://msdn.microsoft.com/en-us/library/gg492153(v=sql.120).aspx

What’s new in SQL Server 2014

http://msdn.microsoft.com/library/bb500435(v=sql.120).aspx

Columnstore Index FAQ:

http://social.technet.microsoft.com/wiki/contents/articles/3540.sql-

server-columnstore-index-faq.aspx