Re: bumping HASH_VERSION to 3

On Tue, Apr 11, 2017 at 11:53 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> On Fri, Mar 31, 2017 at 02:48:05PM -0400, Tom Lane wrote:
>> +1, as long as we're clear on what will happen when pg_upgrade'ing
>> an installation containing hash indexes. I think a minimum requirement is
>> that it succeed and be able to start up, and allow the user to manually
>> REINDEX such indexes afterwards. Bonus points for:
>>
>> 1. teaching pg_upgrade to create a script containing the required REINDEX
>> commands. (I think it's produced scripts for similar requirements in the
>> past.)
>>
>> 2. marking the index invalid so that the system would silently ignore it
>> until it's been reindexed. I think there might be adequate infrastructure
>> for that already thanks to REINDEX CONCURRENTLY, and it'd just be a matter
>> of getting pg_upgrade to hack the indexes' catalog state. (If not, it's
>> probably not worth the trouble.)
>
> We already have code to do all of that, but it was removed from
> pg_upgrade in 9.5. You can still see it in 9.4:
>
> contrib/pg_upgrade/version_old_8_3.c::old_8_3_invalidate_hash_gin_indexes()
>

Thanks for the pointer.

> I would be happy to restore that code and make it work for PG 10.
>

Attached patch implements the two points suggested by Tom. I will add
this to PG-10 open issues list so that we don't forget about this
work, let me know if you think otherwise.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com