Re: Restore referencial integrity

On Mon, Aug 30, 2010 at 5:30 AM, Carlos Henrique Reimer
<carlos.reimer@opendb.com.br> wrote:
> Hi,
>
> We had by mistake dropped the referencial integrety between two huge tables
> and now I'm facing the following messages when trying to recreate the
> foreign key again:
>
> alter table posicoes_controles add
>   CONSTRAINT protocolo FOREIGN KEY (protocolo)
>       REFERENCES posicoes (protocolo) MATCH SIMPLE
>       ON UPDATE NO ACTION ON DELETE CASCADE;
>
> ERROR:  insert or update on table "posicoes_controles" violates foreign key
> constraint "protocolo"
> DETAIL:  Key (protocolo)=(338525035) is not present in table "posicoes".
> ********** Erro **********
> ERROR: insert or update on table "posicoes_controles" violates foreign key
> constraint "protocolo"
> SQL state: 23503
> Detalhe: Key (protocolo)=(338525035) is not present in table "posicoes".
> As the error message tells, the table "posicoes_controles" has values in
> column "protocolo" that are not present in column "protocolo" of table
> "posicoes". This happened because some programs removed rows from table
> "posicoes" while the referencial integrity was dropped.
>
> Now I need to remove all rows from table "posicoes_controles" that has not
> corresponding row in table "posicoes".
>
> As these are huge tables, almost 100GB each, and the server
> hardware restricted (4GB RAM) I would like a suggestion of which command
> or commands should be used from the performance perspective.
>
> Column "protocolo" is "posicoes" table primary key but is not in any index
> colum of table "posicoes_controles".
>
> Thank you very much for any help!
> --
> Reimer
> 47-3347-1724 47-9183-0547 msn: carlos.reimer@opendb.com.br
>
>

Hi,

I guess you could consider the following strategy: Halt the server or
lock the table or something so no program is allowed to delete any
rows on the affected tables. Run a PL/SQL script that will remove rows
from "posicoes_controles" whose foreign key is not present in table
"posics." Then re-issue the foreign key constraint. Then unlock the
table or whatever it is you have to do get programs to be able to use
the tables again.

I hope this helps somewhat.
--
George H
george.dma@gmail.com