Deleteing large bulks of data

Brief background:

We are using SQL Server 2000, and one of the tables stores user
sessions details (each time our users logs into our system we insert a
new record in the session table, and each time user logs out from our
system we insert another record in the same table).
SESSION_ID is the primary key and it is clustered index.
The system produces 5 million session records/day.

The problem:

Each day we transfer the session data (delta only) to other machine and
we want to delete bulk of ~5 million sessions. This should happend
without any interfering of our customers activity ( in the same time,
we should not block the table - new sessions should be created).

What is the best way to perform such task ?generally truncate table xxx ...will be MUCH faster than delete. Be
aware of some of the logging issues associated with truncate table
before you do this. Search your BOL for "truncate table".

MJKulangara
http://sqladventures.blogspot.com|||Truncating table will delete the entire table, and this is not what we
want. We are looing for a method to delete specific sessions (by
specifying the exact sessions ID's).|||rosherman@.hotmail.com (rosherman@.hotmail.com) writes:
> We are using SQL Server 2000, and one of the tables stores user
> sessions details (each time our users logs into our system we insert a
> new record in the session table, and each time user logs out from our
> system we insert another record in the same table).
> SESSION_ID is the primary key and it is clustered index.
> The system produces 5 million session records/day.
> The problem:
> Each day we transfer the session data (delta only) to other machine and
> we want to delete bulk of ~5 million sessions. This should happend
> without any interfering of our customers activity ( in the same time,
> we should not block the table - new sessions should be created).
> What is the best way to perform such task ?

If I understand this correctly, you want to delete the main bulk of the
five million rows, but keep some of them.

I would consider doing something like:

1) Rename the table.
2) Create a new table with the same schema.
3) Insert the rows you want to keep from the old table to the new table.
4) Drop the old table.

You would need to put 1) and 2) into a transaction. During this
transactions logins would be blocked, but it would be a matter of
centiseconds.

If you can find a method to define a clean cut a head, then you could
consider partitioned views. That is, you would have a set of table
that are united in a view, and a CHECK constraint defining which
intervals that go into which table. Insertions would be into the view.
You would transfer one table a time, and then truncate and finally
redefine it to fit another slot in the future.

--
Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/pr...oads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodin...ions/books.mspx|||Thanks. We'll try this method.

Delete matched query

I'm working with a legacy application that stores its data in a SQL Server 2
K
database. I want to write a delete query to delete items from table A, wher
e
there is no match in table B, where the match is based on matches of the two
PK fields.
I tried the following, but got an error: Incorrect syntax near the keyword
'LEFT'
DELETE FROM A
LEFT JOIN B
ON A.ExerciseID = B.ExerciseID
AND A.UserID = B.UserID
WHERE B.UserID IS NULL
Any help would be greatly appreciated.
DaleHow about this?
DELETE A
FROM A
INNER JOIN B
ON A.ExerciseID = B.ExerciseID
AND A.UserID = B.UserID
WHERE B.UserID IS NULL|||Try
DELETE A
From A LEFT JOIN B
ON A.ExerciseID = B.ExerciseID
AND A.UserID = B.UserID
WHERE B.UserID IS NULL
But beware, when you use this syntax, if you uswe Table Aliases, i.e., if
the Tables are actually name dTableA and TableB, then the First line has t
ouse the Alias, not the actual Table Name,. i.e.,
DELETE A
From TableA A Left Join TableB B
ON A.ExerciseID = B.ExerciseID
AND A.UserID = B.UserID
WHERE B.UserID IS NULL
A Much clearer way to code this is to use SQL that mirrors exactly what you
want
Delete TableA
Where Not Exists
(Select * From TableB
Where PK = TableA.PK)
"Dale Fye" wrote:

> I'm working with a legacy application that stores its data in a SQL Server
2K
> database. I want to write a delete query to delete items from table A, wh
ere
> there is no match in table B, where the match is based on matches of the t
wo
> PK fields.
> I tried the following, but got an error: Incorrect syntax near the keyword
> 'LEFT'
> DELETE FROM A
> LEFT JOIN B
> ON A.ExerciseID = B.ExerciseID
> AND A.UserID = B.UserID
> WHERE B.UserID IS NULL
> Any help would be greatly appreciated.
> Dale|||I meant
Delete TableA
Where Not Exists
(Select * From TableB
Where ExerciseID = TableA.ExerciseID
And UserID = TableA.UserID)
"CBretana" wrote:
> Try
> DELETE A
> From A LEFT JOIN B
> ON A.ExerciseID = B.ExerciseID
> AND A.UserID = B.UserID
> WHERE B.UserID IS NULL
> But beware, when you use this syntax, if you uswe Table Aliases, i.e., if
> the Tables are actually name dTableA and TableB, then the First line has t
> ouse the Alias, not the actual Table Name,. i.e.,
> DELETE A
> From TableA A Left Join TableB B
> ON A.ExerciseID = B.ExerciseID
> AND A.UserID = B.UserID
> WHERE B.UserID IS NULL
> A Much clearer way to code this is to use SQL that mirrors exactly what yo
u
> want
> Delete TableA
> Where Not Exists
> (Select * From TableB
> Where PK = TableA.PK)
> "Dale Fye" wrote:
>|||Try this
Delete From A
Where Not Exists(
Select * From B Where B.Col1=A.Col1 And B.Col2=A.Col2
)
Dmitriy
"Dale Fye" <dale.fye@.nospam.com> wrote in message
news:B16B3312-7EDD-4D85-A2D0-7806F2064BEE@.microsoft.com...
> I'm working with a legacy application that stores its data in a SQL Server
2K
> database. I want to write a delete query to delete items from table A,
where
> there is no match in table B, where the match is based on matches of the
two
> PK fields.
> I tried the following, but got an error: Incorrect syntax near the keyword
> 'LEFT'
> DELETE FROM A
> LEFT JOIN B
> ON A.ExerciseID = B.ExerciseID
> AND A.UserID = B.UserID
> WHERE B.UserID IS NULL
> Any help would be greatly appreciated.
> Dale|||Dale Fye wrote:
> I'm working with a legacy application that stores its data in a SQL Server
2K
> database. I want to write a delete query to delete items from table A, wh
ere
> there is no match in table B, where the match is based on matches of the t
wo
> PK fields.
> I tried the following, but got an error: Incorrect syntax near the keyword
> 'LEFT'
> DELETE FROM A
> LEFT JOIN B
> ON A.ExerciseID = B.ExerciseID
> AND A.UserID = B.UserID
> WHERE B.UserID IS NULL
--BEGIN PGP SIGNED MESSAGE--
Hash: SHA1
Try this:
DELETE FROM A
WHERE NOT EXISTS (SELECT * FROM B
WHERE B.ExerciseID = A.ExerciseID
AND B.UserID = A.UserID)
MGFoster:::mgf00 <at> earthlink <decimal-point> net
Oakland, CA (USA)
--BEGIN PGP SIGNATURE--
Version: PGP for Personal Privacy 5.0
Charset: noconv
iQA/ AwUBQjX6lIechKqOuFEgEQIHQQCfe67DnoBuMAKw
lKtCX8+H7Wd9ANAAmwS2
sbyoMnwLgSk2DmyMUtxtgESf
=hYSb
--END PGP SIGNATURE--|||Thanks to all who responded. I've been working in Access so long, I forgot
about Exists and Not Exists.
"CBretana" wrote:
> Try
> DELETE A
> From A LEFT JOIN B
> ON A.ExerciseID = B.ExerciseID
> AND A.UserID = B.UserID
> WHERE B.UserID IS NULL
> But beware, when you use this syntax, if you uswe Table Aliases, i.e., if
> the Tables are actually name dTableA and TableB, then the First line has t
> ouse the Alias, not the actual Table Name,. i.e.,
> DELETE A
> From TableA A Left Join TableB B
> ON A.ExerciseID = B.ExerciseID
> AND A.UserID = B.UserID
> WHERE B.UserID IS NULL
> A Much clearer way to code this is to use SQL that mirrors exactly what yo
u
> want
> Delete TableA
> Where Not Exists
> (Select * From TableB
> Where PK = TableA.PK)
> "Dale Fye" wrote:
>