My table's primary key is an identity column.
When I delete a row, I first copy it to another table and afterwards delete it
from the original table.
When I want to restore the row, I use the SET IDENTITY_INSERT statement, in
order to avoid getting a new value for the identity column.
The only problem is when there are two clients trying to restore rows at the
same time - which causes an error, since the SET IDENTITY_INERT ON statement
can only be issued on one table at a time.
What can I do to fix this problem?Amir Shitrit wrote:
> My table's primary key is an identity column.
> When I delete a row, I first copy it to another table and afterwards
> delete it from the original table.
> When I want to restore the row, I use the SET IDENTITY_INSERT
> statement, in order to avoid getting a new value for the identity
> column.
> The only problem is when there are two clients trying to restore rows
> at the same time - which causes an error, since the SET
> IDENTITY_INERT ON statement can only be issued on one table at a time.
> What can I do to fix this problem?
SET IDENTITY_INSERT can be used by multiple sessions, even on the same
table, without a problem. Are you possibly running a web application
that is using pooled connections and both clients are getting the same
connection? If you're sure each client is using a different connection,
then there should be no problem.
If you are using the same connection, you may want to spawn temporary,
new connections when a restore operation occurs and close them once the
restore is complete.
David Gugick
Imceda Software
www.imceda.com|||Get rid of the IDENTITY Column and come up with a better way of assigning
keys to your rows.
"Amir Shitrit" <AmirShitrit@.discussions.microsoft.com> wrote in message
news:C400EE3C-E209-45F6-809F-CBB33DBC5FAE@.microsoft.com...
> My table's primary key is an identity column.
> When I delete a row, I first copy it to another table and afterwards
> delete it
> from the original table.
> When I want to restore the row, I use the SET IDENTITY_INSERT statement,
> in
> order to avoid getting a new value for the identity column.
> The only problem is when there are two clients trying to restore rows at
> the
> same time - which causes an error, since the SET IDENTITY_INERT ON
> statement
> can only be issued on one table at a time.
> What can I do to fix this problem?|||> When I delete a row, I first copy it to another table and afterwards
> delete it
> from the original table.
> When I want to restore the row, I use the SET IDENTITY_INSERT statement,
> in
> order to avoid getting a new value for the identity column.
This makes no sense to me. Why not just assign a new IDENTITY value, since
you apparently don't have dependent rows referencing the data in the
original table?
IDENTITY should be used only as an artificial key - if you care about what
the value is then don't use IDENTITY.
--
David Portas
SQL Server MVP
--|||"David Portas" wrote:
> > When I delete a row, I first copy it to another table and afterwards
> > delete it
> > from the original table.
> > When I want to restore the row, I use the SET IDENTITY_INSERT statement,
> > in
> > order to avoid getting a new value for the identity column.
> This makes no sense to me. Why not just assign a new IDENTITY value, since
> you apparently don't have dependent rows referencing the data in the
> original table?
> IDENTITY should be used only as an artificial key - if you care about what
> the value is then don't use IDENTITY.
> --
> David Portas
> SQL Server MVP
> --
Well, I do have related records, thus I can't insert the row with a new
IDENTITY if I want to keep the relations.
It goes like this: I have a table full of Customers rows and another table
with CustomersReports rows (which is a child table of the Customers table).
When I delete a customer, I don't really delete it, but rather move it to an
archive table along with it's related CustomersReports child rows.
In another scenario, I might want to restore the Customer row to it's
original table, and restore it's related CustomersReports rows as well.
If I will restore the customer by assigning it a new ID, I will be compelled
to modify the foreign key in the child table as well.
I prefer to avoid it if possible.|||Add a CHAR(1) column called "Archive" and set it to 'Y' or 'N'. Adjust your
queries to include only Archive = 'Y'. The way you're doing it now, you're
leaving a lot of orphaned rows in related tables. From what you've
explained you don't even have Foreign Key constraints set up on these
tables, and won't be able to apply them at any point because of the manner
in which you've set this up.
"Amir Shitrit" <AmirShitrit@.discussions.microsoft.com> wrote in message
news:8578B5F3-08BF-4AB1-A950-8F5BE57AD138@.microsoft.com...
>
> "David Portas" wrote:
>> > When I delete a row, I first copy it to another table and afterwards
>> > delete it
>> > from the original table.
>> > When I want to restore the row, I use the SET IDENTITY_INSERT
>> > statement,
>> > in
>> > order to avoid getting a new value for the identity column.
>> This makes no sense to me. Why not just assign a new IDENTITY value,
>> since
>> you apparently don't have dependent rows referencing the data in the
> > original table?
>> IDENTITY should be used only as an artificial key - if you care about
>> what
>> the value is then don't use IDENTITY.
>> --
>> David Portas
>> SQL Server MVP
>> --
> Well, I do have related records, thus I can't insert the row with a new
> IDENTITY if I want to keep the relations.
> It goes like this: I have a table full of Customers rows and another table
> with CustomersReports rows (which is a child table of the Customers
> table).
> When I delete a customer, I don't really delete it, but rather move it to
> an
> archive table along with it's related CustomersReports child rows.
> In another scenario, I might want to restore the Customer row to it's
> original table, and restore it's related CustomersReports rows as well.
> If I will restore the customer by assigning it a new ID, I will be
> compelled
> to modify the foreign key in the child table as well.
> I prefer to avoid it if possible.|||"Michael C#" wrote:
> Add a CHAR(1) column called "Archive" and set it to 'Y' or 'N'. Adjust your
> queries to include only Archive = 'Y'. The way you're doing it now, you're
> leaving a lot of orphaned rows in related tables. From what you've
> explained you don't even have Foreign Key constraints set up on these
> tables, and won't be able to apply them at any point because of the manner
> in which you've set this up.
> "Amir Shitrit" <AmirShitrit@.discussions.microsoft.com> wrote in message
> news:8578B5F3-08BF-4AB1-A950-8F5BE57AD138@.microsoft.com...
> >
> >
> > "David Portas" wrote:
> >
> >> > When I delete a row, I first copy it to another table and afterwards
> >> > delete it
> >> > from the original table.
> >> > When I want to restore the row, I use the SET IDENTITY_INSERT
> >> > statement,
> >> > in
> >> > order to avoid getting a new value for the identity column.
> >>
> >> This makes no sense to me. Why not just assign a new IDENTITY value,
> >> since
> >> you apparently don't have dependent rows referencing the data in the
> > > original table?
> >>
> >> IDENTITY should be used only as an artificial key - if you care about
> >> what
> >> the value is then don't use IDENTITY.
> >>
> >> --
> >> David Portas
> >> SQL Server MVP
> >> --
> >
> > Well, I do have related records, thus I can't insert the row with a new
> > IDENTITY if I want to keep the relations.
> > It goes like this: I have a table full of Customers rows and another table
> > with CustomersReports rows (which is a child table of the Customers
> > table).
> > When I delete a customer, I don't really delete it, but rather move it to
> > an
> > archive table along with it's related CustomersReports child rows.
> > In another scenario, I might want to restore the Customer row to it's
> > original table, and restore it's related CustomersReports rows as well.
> > If I will restore the customer by assigning it a new ID, I will be
> > compelled
> > to modify the foreign key in the child table as well.
> > I prefer to avoid it if possible.
>
Hi.
I actually do have foreign key constrains, and when I'm moving a row to the
archive, I move all of it's related child rows as well (as I explaind before).
Besides, Adding a column to the original table costs alot more than moving
rows to the archive - both in memory resources and performence.
Managing the table this way is also eazyer.
Thanks anyway.|||"Amir Shitrit" <AmirShitrit@.discussions.microsoft.com> wrote in message
news:2EC17FAD-43E6-41E8-9F6B-F5CACF4912FC@.microsoft.com...
> Hi.
> I actually do have foreign key constrains, and when I'm moving a row to
> the
> archive, I move all of it's related child rows as well (as I explaind
> before).
> Besides, Adding a column to the original table costs alot more than moving
> rows to the archive - both in memory resources and performence.
> Managing the table this way is also eazyer.
> Thanks anyway.
I missed your second post that explains how you're also keeping duplicates
of all your other tables as well to hold copies of your records.
I'm interested in learning more about how adding a CHAR(1) column to a
single table is much less efficient than maintaining and administering a
complete duplicate schema and writing additional code to move rows from one
schema to the other each time you want to eliminate them from your reports.
I'm a little surprised you find it "easier" to implement code that does
this:
INSERT INTO copy_of_schema_table1
SELECT * FROM real_schema_table1
WHERE MainID = 100
INSERT INTO copy_of_schema_table2
SELECT * FROM real_schema_table2
WHERE MainID = 100
--repeat for each table...
DELETE FROM real_schema_table2
WHERE MainID = 100
DELETE FROM real_schema_table1
WHERE MainID = 100
--repeat for each table...
All this to archive One set of related rows. Ahhh, probably better wrap all
of these INSERTs and DELETEs into a single transaction, so you don't end up
with out-of-sync schemas. Oh yeah, can't forget the IDENTITY_INSERT
statements. And it's a 'simple' matter of doing the reverse to "un-archive"
it. Yet something like this is 'inefficient'?
UPDATE schema_table1
SET Archive = 'Y'
WHERE MainID = 100
To "archive" a record, and
UPDATE schema_table1
SET Archive = 'N'
WHERE MainID = 100
To "un-archive" it.
Wow. As they say, to each his own, and whatever you find most clever.|||> Well, I do have related records, thus I can't insert the row with a new
> IDENTITY if I want to keep the relations.
In fact it should be easy to do this. See the example below. However, I
entirely agree with Michael. It's unnecessary and inefficient to move data
around in this way. Copying data from one table to another is a lot more
expensive than adding a one-byte column by any measure that I can think of.
CREATE TABLE Customers (cust_id INTEGER IDENTITY PRIMARY KEY, cust_name
VARCHAR(50) NOT NULL UNIQUE /* Note the alternate key */ )
CREATE TABLE CustomerReports (..., cust_id INTEGER REFERENCES Customrers
(cust_id), ...)
INSERT INTO Customers (cust_name, ...)
SELECT cust_name,
FROM CustomersArchive
WHERE ...
INSERT INTO CustomerReports (cust_id, ... /* other columns */)
SELECT C.cust_id, R. ... /* other columns */
FROM CustomerReportsArchive AS R
JOIN CustomersArchive AS A
ON R.cust_id = A.cust_id
JOIN Customers AS C
ON A.cust_name = C.cust_name
--
David Portas
SQL Server MVP
--|||On Sun, 08 May 2005 11:25:15 -0700, Amir Shitrit wrote:
> Hi.
> I actually do have foreign key constrains, and when I'm moving a row to the
> archive, I move all of it's related child rows as well (as I explaind before).
> Besides, Adding a column to the original table costs alot more than moving
> rows to the archive - both in memory resources and performence.
> Managing the table this way is also eazyer.
> Thanks anyway.
Although I fully agree with Michael and David - this is just a bad idea,
as far as I can see, you could do it using application locks. Like this:
CREATE PROCEDURE NeverRunsInParallel
AS
DECLARE @.result int
EXEC @.result = sp_getapplock @.Resource = 'myLock', @.LockMode = 'Exclusive'
IF @.result => 0
BEGIN
-- Do your thing, secure in the fact that
-- no other connection will do it at the same
-- time.
END
EXEC sp_releaseapplock @.Resource = 'myLock1'
<<
HTH,
Andrés Taylor
