Re: finding if a foreign key is in use

On Tuesday 29 June 2004 07:19 pm, Phil Endecott wrote:
> Kenneth Gonsalves <lawgon(at)thenilgiris(dot)com> wrote:
> > in my app i have a table where the id serves as a foreign key for
> > one or more other tables. if i want to delete a row in the table,
> > i currently search the other tables where this table is referenced
> > to see if the row is in use - and then, if not in use, permit
> > deletion.

> > Now if i want the delete button in my app to be disabled whenever
> > a row that is in use is selected, searching the database every time
> > would dramatically slow down the app.
>
> Basically you do have to do this search. But it won't be too slow if you
> create an index on the foreign key.

pity. thought postgres would have some function like 'in_use' to tell when a
row that is used as a foreign key is in actual use and hence cannot be
deleted. surely, in a database of millions of records, it wouldnt have search
them all to find if the row is in use? in my case the id field serves as a
foreign key in several tables
--
regards
kg

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