I have a data dump then I wanna import it to another DB (Oracle 10g). The destination DB has already tables (no data) and some foreign key constraints. I will import the data by tables in order to avoid constraint errors. If does anyone know any easier ways, please teach me ?. (Oracle's import tool does not have functions to recognize relations between tables automatically, does it ?)
You can disable all foreign keys first:
begin
for cnst in (SELECT constraint_name, table_name FROM user_constraints WHERE constraint_type ='R') loop
execute immediate 'alter table '|| cnst.table_name||' disable constraint ' || cnst.constraint_name ;
end loop;
end;
After loading your data do the same to enable them back (just change the alter table command to enable instead of disable
But this is risky, because if the data won't meet your contraints - you'll have a problem ...
Assuming that you have a schema-level export, the source schema had those same foreign key constraints, and all the foreign key constraints are between tables in the same schema, the import utility should automatically take care of the foreign key constraints. You shouldn't need to do anything for that (though, of course, you'll have to ignore errors when you do the import because it will try to create the tables and get an error that they already exist).
Related
When we use import foreign schema in oracle_fdw, there is no option for IF NOT EXISTS.
Due to which if we re-execute the import foreign schema command to import the newly added tables/view we get the error that relation already exists.
As we are not aware of the table/view which were not added in the previous execution it becomes difficult to specify them in LIMIT/EXCEPT clause
Is there any work around available to achieve the IF NOT EXISTS functionality
There is no direct way to do that, but you can first find the foreign tables that already exist in the target schema and list them in the EXCEPT clause of IMPORT FOREIGN SCHEMA.
To find all foreign tables in a schema:
SELECT relname
FROM pg_class
WHERE relkind = 'f'
AND relnamespace = 'schemaname'::regnamespace;
Then
IMPORT FOREIGN SCHEMA "XYZ"
EXCEPT (/* list from above */)
FROM SERVER oraserver
INTO schemaname;
I was looking for the STDIN option, to use FOREIGN TABLE in similar way as COPY... And discovery a "bug" in the Guide: there are no documentation about options at official sql-create-foreign-table Guide. No link, nothing:
OPTIONS ( option 'value' [, ...] )
Options to be associated with the new foreign table or one of its columns. ...
So, to lack of information transformed this question in two:
It is possible to use STDIN with FOREIGN TABLE?
Where the "OPTIONS" documentation?
edit to add example
CREATE FOREIGN TABLE t1 (
aa text,
bb bigint
) SERVER files OPTIONS (
filename '/tmp/bigBigdata.csv',
format 'csv',
header 'true'
;
Is a classic ugly PostgreSQL limitation on use filesystem, so I need a terminal solution ... Imagine on shell something with pipes, as
psql -c "ALTER FOREIGN TABLE t1 ... STDIN; CREATE TABLE t2 AS SELECT trim(aa) as aa, bb+1 as bb FROM t WHERE bb>999" < /thePath/bigBigdata.csv
Is a kind of "no direct copy, only filtering a stream of data", and creating a final table t2 from this filtered stream.
I think you are confused about foreign tables, I'll try to explain.
The data of a foreign table do not reside in PostgreSQL, but in an external data source (a file, a different database, etc.).
The foreign table is just a way to access these data from PostgreSQL as if they were a PostgreSQL table.
You can COPY to a foreign table FROM STDIN if the foreign data wrapper supports it, but that has nothing to with CREATE FOREIGN TABLE. CREATE FOREIGN TABLE defines how PostgreSQL should locate the external data and what the format of the data is.
There is no documentation of the options in CREATE FOREIGN TABLE because they depend on the foreign data wrapper you are using.
Look at the documentation of the foreign data wrapper.
Your example makes clear that what you need is not a foreign table, but a temporary table into which you can COPY the raw data which you later want to modify. You cannot use file_fdw for data that resides on the client machine.
Inspired by creating a temporary table from a query using sqlalchemy orm I had similar requirement but only needs PrimaryKey Constraint and want to add ForeinKeyConstraint based on new temp tables created.
I have added only foreign constraint by checking if the constraint is of type PrimaryKeyConstraint then add in constraints
constraints = [c.copy() for c in table.constraints if isinstance(c,PrimaryKeyConstraint)]
This is fine but I want to create a foreign key constraint on two newly created tables.
I have tried
constraints.append(ForeignKeyConstraint(['id'],['schema2.temp_table1.id']))
and as suggested added back to the table
temp_table = Table(name, metadata, *(cols + constraints), schema=schema)
But it is taking a long time to create and insert the data. Any suggestions would be helpful.
I searched for this problem. But my postgres user has enough grant and I do not think I have misspelling error. However I am newbie.
I have this error message:
21:38:03 set search_path='public'
21:38:03 ALTER TABLE public.tbl_user DROP CONSTRAINT "fk-user-access-user-id"
21:38:03 ERROR: constraint "fk-user-access-user-id" of relation "tbl_user" does not exist
I use the PhpStorm. I just open the database view, expanded the tbl_user table, right click and select "drop". And I got this error in the console.
So the above SQL command generated by the PhpStorm.
Then I tried with these commands manually on Ubuntu:
ALTER TABLE tbl_user DROP CONSTRAINT "fk-user-access-user-id"
ALTER TABLE "tbl_user" DROP CONSTRAINT "fk-user-access-user-id"
But I get the same error.
In the PhpStorm I see this definition:
"fk-user-access-user-id" FOREIGN KEY (access_id) REFERENCES tbl_access (id)
The tbl_access table exists with the primary id key.
I do not understand this error message, because the "fk-user-access-user-id" foreign key is at the tbl_user and so for me the 'relation "tbl_user" does not exist' strange. I do not understand.
I tried to find similar problem on StackOverflow, but I gave up after 20x question reading.
By the way, the postgres code was generated by the Yii framework.
$this->addColumn('{{%user}}', 'access_id', $this->integer()->notNull()->defaultValue(1)->after('status'));
$this->addForeignKey('fk-user-access-user-id', '{{%user}}', 'access_id', '{{%access}}', 'id');
first row mean add access_id column to the user table.
second row: create foreign key with 'fk-user...' name on tbl_user table's access_id column references to tbl_access table's id column.
So I used this PHP code to generate this SQL commands. I prefer this way because for me the migration files are very useful.
Most likely the definition and actual implementation in your underlying DB has changed from what the app has recorded. Depending on what the history is, either a change in the app for that foreign key relationship was not migrated to persist the change at the database level, or someone has executed some operation directly at the DB level to remove the relationship. You will need to sync up the app layer to the DB at this point I would think.
I tried to change all foreign keys in PostgreSQL at once to cascade on delete:
UPDATE pg_catalog.pg_constraint
SET confupdtype='c', confdeltype='c', confmatchtype='u'
WHERE connamespace=2200;
There are no errors, and when I inspect the tables with pgadmin, it looks right, but when I try to delete a referenced table-line it comes to a constraint error. Just the SQL statement works:
ALTER TABLE tblname
DROP CONSTRAINT IF EXISTS fk3e2e4a8ff123848a;
ALTER TABLE tblname
ADD CONSTRAINT fk3e2e4a8ff123848a FOREIGN KEY (field)
REFERENCES othertable (id) MATCH SIMPLE
ON UPDATE CASCADE ON DELETE CASCADE;
Any idea why changing pg_catalog.pg_constraint is not working? even restarting the service after didn't help.
Really you shouldn't be updating pg_* tables.
Use a command like
ALTER TABLE YOURTABLE DISABLE TRIGGER;
Check this link out.
http://archives.postgresql.org/pgsql-general/2011-10/msg00802.php