Re: foreign key locks

On 2012-11-14 13:27:26 -0300, Alvaro Herrera wrote:
> Alvaro Herrera wrote:
>
> > > * In heap_lock_tuple's XMAX_IS_MULTI case
> > >
> > > [snip]
> > >
> > > why is it membermode > mode and not membermode >= mode?
> >
> > Uh, that's a bug. Fixed. As noticed in the comment above that snippet,
> > there was a deadlock possible here. Maybe I should add a test to ensure
> > this doesn't happen.
>
> Done:
> https://github.com/alvherre/postgres/commit/df2847e38198e99f57e52490e1e9391ebb70d770
>
> (I don't think this is worth a v24 submission).

One more observation:
/*
* Get and lock the updated version of the row; if fail, return
NULL.
*/
- copyTuple = EvalPlanQualFetch(estate, relation, LockTupleExclusive,
+ copyTuple = EvalPlanQualFetch(estate, relation, LockTupleNoKeyExclusive,

That doesn't seem to be correct to me. Why is it ok to acquire a
potentially too low locklevel here?

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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