I was querying against SQL Server to get all columns, that are referenced to other columns. By accident I saw, that the column "tenantId" (table "AbpUsers") is not referenced to AbpTenants.Id.
I asked some of my collegues, that are "used" to know aspnetboilerplate, just to clarify. Everyone was surprised, as I am.
Just for testing purposes I created a new database by "Update-database". Before running the application, I added the "missing" foreign-Key-reference manually. And? Nothing happened. Nothing bad happened. Everything works, as it did without the foreign-key-reference...
ALTER TABLE [dbo].[AbpUsers] WITH CHECK ADD CONSTRAINT [FK_AbpUsers_AbpTenants_TenantId] FOREIGN KEY([TenantId])
REFERENCES [dbo].[AbpTenants] ([Id])
GO
ALTER TABLE [dbo].[AbpUsers] CHECK CONSTRAINT [FK_AbpUsers_AbpTenants_TenantId]
GO
As expected my whole application works fine, even when the initial content builder is running.
Keys exist mainly to protect referential integrity of the database. If you have no Cascade Update or Cascade Delete options on, then maybe this key was removed to make deleting things easier for someone who did not know what they were doing.
Related
I'm beginer and I'm working on oracle 12c database so, In my database project I want to apply cascade on delete and on update simultaneously as i did in mysql but when i apply tha same technique in oracle it show me the error so how can i do that?
There is no ON UPDATE CASCADE on Oracle. While you can probably argue updating a table's primary key is valid in SQL, you probably should not, hence the decision of Oracle not to implement it.
More info here:
https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:5773459616034
EDIT: As discussed in comments below, think of that constraint as a way Oracle prevents people from doing something wrong (updating primary keys).
The correct way to handle the case of a primary key that might be updated is to create a separate field that will act as the surrogate primary key. The surrogate key, of course, is immutable.
The danger of using a natural key as primary key is discussed there.
I apologize if I repeat the question, but I did not find a similar one.
I have added a unique constraint on an already existent table. We use MariaDB.
I have used the annotation:
#Table(uniqueConstraints={#UniqueConstraint(name="autonomy_name_energyType", columnNames={"autonomy","name","energyType"})})
The unit tests pass, but in the DB I am still allowed to create duplicates.
Do I need an ALTER table too? By checking the table I can see there are no constraints added to it.
Thanks
As explained in these SO posts :
Unique constraint not created in JPA
#Column(unique=true) does not seem to work
An explicit alter table query is needed for ur constaints to take effect on the db level.
As an extra info, it would have worked if the table was being re-created via JPA. see :
Add a unique constraint over muliple reference columns
The diagram has over 40 tables, most of them have a primary key defined.
For some reason there is this one table, which has a primary key defined, but that's being ignored when I export the model to a DDL script.
This is the "offending" key (even though it's checked it is nowhere to be found on the generated DDL script):
Has anybody had the same problem? Any ideas on how to solve it?
[EDIT] This is where the key is defined:
And this is the DDL preview (yes, the primary key shows up there):
This is what happens if I try to generate the DDL for just that table (primary key still not generated):
I was finally able to identify and reproduce the problem.
It was a simple conflict of constraints.
Table MIEMBROS had a mandatory 1 to n relationship (foreign key) from another table on its primary key column and vice-versa (there was a foreign key on MIEMBROS against the other table's primary key).
This kind of relationship between two tables makes it impossible to add a record to any of them: The insert operation will return an error complaining about the foreign key restriction pointing the other table.
Anyway I realized that one of the relationships was 0 to n so I simply unchecked the "mandatory" checkbox on the foreign key definition and everything went fine.
So, in a nutshell: The Data Modeler "fails" silently if you are defining a mutual relationship (two foreign keys, one on each table against the other table) on non nullable unique columns, by not generating the primary key of one of the tables.
Such an odd behavior, if you ask me!
"This kind of relationship between two tables makes it impossible to add a record to any of them: The insert operation will return an error complaining about the foreign key restriction pointing the other table."
Actually, if you have deferred constraints, this is not impossible. The constraints can be enforced, for example, at commit time rather than immediately at insert time.
From the Data Modeler menu under File, I used Export -> DDL File. The keys appeared in the DDL, then when I went back to the diagram and did DDL Preview, it showed all the missing stuff.
I'm deleting this row from a table and it has a bunch of cascades on the FKs and eventually it gives me this error:
ERROR: insert or update on table "foo_route" violates foreign key constraint "foo_route_bar_fk"
SQL state: 23503
Detail: Key (bar_key)=(2176) is not present in table "bar".
foo_route_bar_fk is defined like this:
ALTER TABLE foo_route
ADD CONSTRAINT foo_route_bar_fk FOREIGN KEY (bar_key) REFERENCES bar (bar_key)
MATCH SIMPLE ON UPDATE NO ACTION ON DELETE CASCADE;
I'm getting this error by deleting a table unrelated to both of these. I think what's happening is a trigger or a cascade is causing this error, but it's difficult to find out why.
My question is, how do you debug issues like this in postgresql? What are the series of steps that caused this error? Postgresql only tells me the result of the last thing it did before it failed. If this were code the error would give an extremely helpful stack trace. Is there a way to see something like that in Postgresql?
Typically your postgresql log will include the statement which triggered the error. That should allow you to follow the chains of cascading events.
One thing I would suggest however is that you might want to draw out a map of fkeys and look at the mappings of ON events on foreign keys. If it were me I would start with a schema only dump or pg_autodoc output, and go from there. The obvious problem is that you have deletes cascading in cases where it can't so you need to take a look and rethink things here.
We use mini profiler in two ways:
On developer machines with the pop-up
In our staging/prod environments with SqlServerStorage storing to MS SQL
After a few weeks we find that writing to the profiling DB takes a long time (seconds), and is causing real issues on the site. Truncating all profiler tables resolves the issue.
Looking through the SqlServerStorage code, it appears the inserts also do a check to make sure a row with that id doesnt already exist. Is this to ensure DB agnostic code? This seems it would introduce a massive penalty as the number of rows increases.
How would I go about removing the performance penalty from the performance profiler? Is anyone else experiencing this slow down? Or is it something we are doing wrong?
Cheers for any help or advice.
Hmm, it looks like I made a huge mistake in how that MiniProfilers table was created when I forgot about primary key being clustered by default... and the clustered index is a GUID column, a very big no-no.
Because data is physically stored on disk in the same order as the clustered index (indeed, one could say the table is the clustered index), SQL Server has to keep every newly inserted row in that physical order. This becomes a nightmare to keep sorted when we're using essentially a random number.
The fix is to add an auto-increasing int and switch the primary key to that, just like all the other tables (why I overlooked this, I don't remember... we don't use this storage provider here on Stack Overflow or this issue would have been found long ago).
I'll update the table creation scripts and provide you with something to migrate your current table in a bit.
Edit
After looking at this again, the main MiniProfilers table could just be a heap, meaning no clustered index. All access to the rows is by that guid ID column, so no physical ordering would help.
If you don't want to recreate your MiniProfiler sql tables, you can use this script to make the primary key nonclustered:
-- first remove the clustered index from the primary key
declare #clusteredIndex varchar(50);
select #clusteredIndex = name
from sys.indexes
where type_desc = 'CLUSTERED'
and object_name(object_id) = 'MiniProfilers';
exec ('alter table MiniProfilers drop constraint ' + #clusteredIndex);
-- and then make it non-clustered
alter table MiniProfilers add constraint
PK_MiniProfilers primary key nonclustered (Id);
Another Edit
Alrighty, I've updated the creation scripts and added indexes for most querying - see the code here in GitHub.
I would highly recommended dropping all your existing tables and rerunning the updated script.