RE: foreign key introduces unnecessary locking ?

Try this for both FK tables:

create table tmp2(idx2 int4, col2 int4, constraint
tmpcon2 foreign key(col2) references tmp1(idx) INITIALLY DEFERRED);

This will defer constraint checks till transaction commit...
though constraint triggers should use SnapshotDirty instead of
SELECT FOR UPDATE anyway.

Did you consider this, Jan?

Vadim

> When two tables (table2 and table3) have foreign keys
> referring to a common table(table1), I am unable to
> have 2 concurrent transactions - one performing insert
> on table1 and the other on table2, when the records
> being inserted have the same foreign key.
>
> If I use JDBC, one of the transactions aborts.
> If I open 2 psql sessions and try the same, one just
> waits and does not show the prompt until the other
> transaction has been committed or aborted.
>
> For example,
> create table tmp1(idx int4, data int4);
> create table tmp2(idx2 int4, col2 int4, constraint
> tmpcon2 foreign key(col2) references tmp1(idx));
> create table tmp3(idx3 int4, col3 int4, constraint
> tmpcon3 foreign key(col3) references tmp1(idx));
> insert into tmp1 values(1, 1);
>
> Transaction 1 :
> begin work;
> insert into tmp2 values(2, 1);
>
> Transaction2 :
> begin work;
> insert into tmp3 values(3,1);
>
> Since such transactions are common for me, for the
> time-being I have dropped the foreign key constraint.
> Any ideas ?
>
> Rini
>
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