Maximum size of index key

we all knew Maximum size of an index key is limited to 900 bytes..But with SQlServer 2016,this limit has been removed..

Below is a sample demo of the same

---Run below query on SQLServer 2012

create table dbo.test(
id int,
col1 varchar(1700)
)

create index nci_test on dbo.test
(col1)
include(id)

now try to run below queries and you will be greeted with error on second query

insert into dbo.test
values (1,'a')

insert into dbo.test
values (1,replicate('a',1000))

below is the error message

Msg 1946, Level 16, State 3, Line 1 Operation failed. The index entry of length 1000 bytes for the index ‘nci_test’ exceeds the maximum length of 900 bytes

Now try modfying above table DDL little bit like below

---run the query on SQL2016

create table dbo.test(
id int,
col1 varchar(1705)
)

create index nci_test on dbo.test
(col1)
include(id)

Below is the warning ,you will get

Warning! The maximum key length for a nonclustered index is 1700 bytes. The index ‘nci_test’ has maximum length of 1705 bytes. For some combination of large values, the insert/update operation will fail.

You can download the demo scripts used here