Load the files into a temp table and go from there...
COPY ... FROM file;
UPDATE existing_table SET ... WHERE ...;
INSERT INTO existing_table SELECT * FROM temp_table WHERE NOT EXISTS(
SELECT * FROM existing_table WHERE ...)
On Wed, Mar 22, 2006 at 10:32:10AM -0500, ashah wrote:
> I have a database with foreign keys enabled on the schema. I receive different
> files, some of them are huge. And I need to load these files in the database
> every night. There are several scenerios that I want to design an optimal
> solution for -
>
> 1. One of the file has around 80K records and I have to delete everything from
> the table and load this file. The provider never provides a "delta file" so I
> dont have a way to identify which records are already present and which are
> new. If I dont delete everything and insert fresh, I have to make around 80K
> selects to decide if the records exist or not. Now there are lot of tables
> that have foreign keys linked with this table so unless I disable the foreign
> keys, I cannot really delete anything from this table. What would be a good
> practise here?
>
> 2. Another file that I receive has around 150K records that I need to load in
> the database. Now one of the fields is logically a "foreign key" to another
> table, and it is linked to the parent table via a database generated unique
> ID instead of the actual value. But the file comes with the actual value. So
> once again, I have to either drop the foreign key, or make 150K selects to
> determine the serial ID so that the foreign key is satisfied. What would be a
> good strategy in this scenerio ?
>
> Please pardon my inexperience with database !
>
> Thanks,
> Amit
>
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Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
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