June 7, 2016 at 9:27 am
My table looks like this
email project_name
test@test.com lab1
test@test.com lab2
test@test.com lab3
test@test.com lab4
trial@test.com rm1
trial@test.com rm2
trial@test.com rm3
But want it to look like this
email project_name
test@test.com lab1, lab2, lab3, lab4
trial@test.com rm1,rm2,rm3,
My query looks like this, how can I make it faster? This query has been running for 6hrs already
select distinct email ,
STUFF((Select ','+project_name
from dbo.[UMG sent 2016] as T1
where T1.email=T2.email
FOR XML PATH('')),1,1,'') from dbo.[UMG sent 2016] as T2;
FYI- my table has 2.6m records
June 7, 2016 at 9:30 am
Please post a copy of the execution plan.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.
June 7, 2016 at 9:33 am
run sp_whoisactive to see how much work it has been doing, if blocking is happening, what it is waiting on (my guess is cxpacket or some form of IO), use the delay option to see work done in 60 seconds, get the plan, etc, etc.
sp_whoisactive can be found on sqlblog.com and there is a 30-day series about how to use it. It is self-documented and totally awesomesauce!
Best,
Kevin G. Boles
SQL Server Consultant
SQL MVP 2007-2012
TheSQLGuru on googles mail service
June 7, 2016 at 9:41 am
I would guess that blocking is happening somewhere in your db. Maybe there's an open transaction. Even with 2.6m rows, it shouldn't take hours to complete.
However, this should be faster as the concatenation happens once per group instead of once per row.
SELECT email,
STUFF((SELECT ','+project_name
FROM dbo.[UMG sent 2016] as T1
WHERE T1.email=T2.email
FOR XML PATH('')),1,1,'')
FROM dbo.[UMG sent 2016] as T2
GROUP BY email;
June 7, 2016 at 9:45 am
Not sure if this will be any better, but it is what I would have written.
with basedata as (
select distinct
from
dbo.[UMG sent 2016]
)
select
bd.email,
ca.Projects
from
basedata bd
cross apply (select STUFF((select ',' + project_name
from dbo.[UMG sent 2016] as T1
where T1.email = bd.email
for xml path(''),TYPE).value('.','varchar(max)'),1,1,''))ca(Projects);
Also, I would check your indexing on the table, especially if this query is run often.
June 7, 2016 at 8:49 pm
How long does it take to run this?
DECLARE @basedata table(
email NVARCHAR(200) COLLATE DATABASE_DEFAULT,
project_name VARCHAR(200) COLLATE DATABASE_DEFAULT
PRIMARY KEY (email, project_name)
)
INSERT INTO @basedata ( email, project_name )
SELECT email, project_name
FROM dbo.[UMG sent 2016]
WHERE email > '' AND project_name > ''
GROUP BY email, project_name
ORDER BY email, project_name
_____________
Code for TallyGenerator
June 7, 2016 at 10:28 pm
you can give the complete query and execution plan so we can provide bit more hand full information.
June 8, 2016 at 2:29 am
That took 46 seconds.
I tried select * from @basedata, but it didn't work. It says 'must declare the table variable @basedata'. I'm new to sql so apologies if this is a silly question
June 8, 2016 at 2:30 am
Thanks, that works abit faster but its still very slow. 16hrs and no where near done
June 8, 2016 at 3:26 am
IA123 (6/8/2016)
That took 46 seconds.I tried select * from @basedata, but it didn't work. It says 'must declare the table variable @basedata'. I'm new to sql so apologies if this is a silly question
Assuming you are referring to Sergiy's query, then that's roughly how long your query might be expected to take. Since your query is taking many times longer than this, then you should assume that the pseudocode you show in your first post isn't fully representative of your actual query. Now might be a good time to post it.
For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden
June 8, 2016 at 4:26 am
IA123 (6/8/2016)
That took 46 seconds.I tried select * from @basedata, but it didn't work. It says 'must declare the table variable @basedata'. I'm new to sql so apologies if this is a silly question
Table variables exist within a scope of the same batch.
Just like any other variable.
When execution is completed all variables, including table variables, are cleared.
Your solution is ready.
Just take your query, replace your table name with table variable and place it right after my query which took 46 seconds.
Declare @basedata ....
......
select email ,
STUFF((Select ','+project_name
from @basedata as T1
where T1.email=T2.email
FOR XML PATH('')),1,1,'') from @basedata as T2
GROUP BY email;
Then run it altogether.
Please note - I used GROUP BY instead of DISTINCT.
You should do it too.
_____________
Code for TallyGenerator
June 8, 2016 at 7:00 am
1) Did you do what I said about sp_whoisactive??
2) How much memory do you have on this sql server? IIRC XML can be a MASSIVE consumer of memory and if you don't have enough you will be spooling to disk (or you could just be waiting for a memory grant).
Best,
Kevin G. Boles
SQL Server Consultant
SQL MVP 2007-2012
TheSQLGuru on googles mail service
June 8, 2016 at 7:45 am
There's something going on with your server. Taking 16 hours to complete a single query is insane.
We're assuming this is a table, but if it's a view, that could be another problem. I just run the query on my laptop creating almost 8 million rows and the query completed in one minute.
We need your help to get more information on where the problem might be. Phil asked for the execution plan and Kevin asked you to run sp_whoisactive. Those are good starts to find the root cause of your problem.
June 8, 2016 at 9:43 am
error says table variable must declare can you share the full script will be easy to find where this missing to get the reference .
June 8, 2016 at 6:08 pm
Here was the first part:
Sergiy (6/7/2016)
How long does it take to run this?
DECLARE @basedata table(email NVARCHAR(200) COLLATE DATABASE_DEFAULT,
project_name VARCHAR(200) COLLATE DATABASE_DEFAULT
PRIMARY KEY (email, project_name)
)
INSERT INTO @basedata ( email, project_name )
SELECT email, project_name
FROM dbo.[UMG sent 2016]
WHERE email > '' AND project_name > ''
GROUP BY email, project_name
ORDER BY email, project_name
_____________
Code for TallyGenerator
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