Re: hash_search and out of memory

On Thu, Oct 18, 2012 at 8:35 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I wrote:
>> Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com> writes:
>>> If OOM happens during expand_table() in hash_search_with_hash_value()
>>> for RelationCacheInsert,
>
> the palloc-based allocator does throw
> errors. I think that when that was designed, we were thinking that
> palloc-based hash tables would be thrown away anyway after an error,
> but of course that's not true for long-lived tables such as the relcache
> hash table.
>
> I'm not terribly comfortable with trying to use a PG_TRY block to catch
> an OOM error - there are too many ways that could break, and this code
> path is by definition not very testable. I think moving up the
> expand_table action is probably the best bet. Will you submit a patch?

Here it is. I factored out the bucket finding code to re-calculate it
after expansion.

Thanks,
--
Hitoshi Harada