Re: xml_is_document and selective pg_re_throw

> No, I don't see any particular risk there. The places that might throw
> ERRCODE_INVALID_XML_DOCUMENT are sufficiently few (as in, exactly one,
> in this usage) that we can have reasonable confidence we know what the
> system state is when we catch that error.
>
>
Hmmm, I was writing some code in which I happened to hold a LWLock when
this function was called. The first catch/rethrow cleaned up the
InterruptHoldoffCount value. A subsequent release of that LWLock tripped up
the (Assert(InterruptHoldoffCount > 0);) inside RESUME_INTERRUPTS().

I know holding an lwlock like this might not be a good idea, but this
behavior just got me thinking about other probable issues.

Regards,
Nikhils

> > A better way would have been to modify xml_parse to take an additional
> > boolean argument "to_rethrow" and not to rethrow if that is false?
>
> We could do that, but it would greatly complicate xml_parse IMO, since
> it still needs its own PG_TRY block to handle other error cases, and
> only one of those error cases ought to optionally return failure instead
> of re-throwing.
>
> regards, tom lane
>