SQL Server Update very slow query

I ran the following query on a previous years data and it took 3 hours, this year it took 13 days. I don't know why this is though. Any help would be much appreciated.

I have just tested the queries in the old SQL server and it works in 3 hours. Therefore the problem must have something to do with the new SQL server I created. Do you have any ideas what the problem might be?

The query:

USE [ABCJan] CREATE INDEX Link_Oct ON ABCJan2014 (Link_ref) GO CREATE INDEX Day_Oct ON ABCJan2014 (date_1) GO UPDATE ABCJan2014 SET ABCJan2014.link_id = LT.link_id FROM ABCJan2014 MT INNER JOIN [Central].[dbo].[LookUp_ABC_20142015] LT ON MT.Link_ref = LT.Link_ref UPDATE ABCJan2014 SET SumAvJT = ABCJan2014.av_jt * ABCJan2014.n UPDATE ABCJan2014 SET ABCJan2014.DayType = LT2.DayType FROM ABCJan2014 MT INNER JOIN [Central].[dbo].[ABC_20142015_days] LT2 ON MT.date_1 = LT2.date1

With the following data structures:

ABCJan2014 (70 million rows - NO UNIQUE IDENTIFIER - Link_ref & date_1 together are unique)

Link_ID nvarchar (17) Link_ref int Date_1 smalldatetime N int Av_jt int SumAvJT decimal(38,14) DayType nvarchar (50)

LookUp_ABC_20142015

Link_ID nvarchar (17) PRIMARY KEY Link_ref int INDEXED Link_metres int

ABC_20142015_days

Date1 smalldatetime PRIMARY KEY & INDEXED DayType nvarchar(50) EXECUTION PLAN

It appears to be this part of the query that is taking such a long time.

Thanks again for any help, I'm pulling my hair out.

If you look at the execution plan the time is in the actual update

Look at the log file

Is the log file on a fast disk?

Is the log file on the same physical disk?

Is the log file required to grow?

Size the log file to like 1/2 the size of the data file

As far as indexes test and tune this

If the join columns are indexed not much to do here

select count(*) FROM ABCJan2014 MT INNER JOIN [Central].[dbo].[LookUp_ABC_20142015] LT ON MT.Link_ref = LT.Link_ref select count(*) FROM ABCJan2014 MT INNER JOIN [Central].[dbo].[ABC_20142015_days] LT2 ON MT.date_1 = LT2.date1

Start with a top (1000) to get update tuning working

For grins please give this a try

Please post this query plan

(do NOT add an index to ABCJan2014 link_id)

UPDATE top (1000) ABCJan2014 SET MT.link_id = LT.link_id FROM ABCJan2014 MT JOIN [Central].[dbo].[LookUp_ABC_20142015] LT ON MT.Link_ref = LT.Link_ref AND MT.link_id <> LT.link_id

If LookUp_ABC_20142015 is not active then add a nolock

JOIN [Central].[dbo].[LookUp_ABC_20142015] LT with (nolock)

nvarchar (17) for a PK to me is just strange

why n - do you really have some unicode?

why not just char(17) and let it allocate space?