Sequence vs identity

Question

SQL Server 2012 introduced Sequence as a new feature, same as in Oracle and Postgres. Where sequences are preferred over identities? And why do we need sequence

Answer 1

Although sequences provide more flexibility than identity columns, I didn't find they had any performance benefits.

I found performance using identity was consistently 3x faster than using sequence for batch inserts.

I inserted approx 1.5M rows and performance was:

• 14 seconds for identity
• 45 seconds for sequence

I inserted the rows into a table which used sequence object via a table default:

NEXT VALUE for for

and also tried specifying sequence value in select statement:

SELECT NEXT VALUE for ,  from 
Both were the same factor slower than the identity method. I used the default cache option for the sequence.
The article referenced in Arion's first link shows performance for row-by-row insert and difference between identity and sequence was 16.6 seconds to 14.3 seconds for 10,000 inserts.
The Caching option has a big impact on performance, but identity is faster for higher volumes (+1M rows)
See this link for an indepth analysis as per utly4life's comment.

                                                        

              
                
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