Re: Hash index creation warning

On Mon, Jun 22, 2015 at 8:46 PM, Michael Paquier
<michael.paquier@gmail.com> wrote:
> On Tue, Jun 23, 2015 at 9:06 AM, Jim Nasby <Jim.Nasby@bluetreble.com> wrote:
>> On 6/12/15 5:00 PM, Thom Brown wrote:
>>>
>>> On 18 October 2014 at 15:36, Bruce Momjian <bruce@momjian.us> wrote:
>>>>
>>>> On Fri, Oct 17, 2014 at 02:36:55PM -0400, Bruce Momjian wrote:
>>>>>
>>>>> On Fri, Oct 17, 2014 at 12:56:52PM -0400, Tom Lane wrote:
>>>>>>
>>>>>> David G Johnston <david.g.johnston@gmail.com> writes:
>>>>>>>
>>>>>>> The question is whether we explain the implications of not being
>>>>>>> WAL-logged
>>>>>>> in an error message or simply state the fact and let the documentation
>>>>>>> explain the hazards - basically just output:
>>>>>>> "hash indexes are not WAL-logged and their use is discouraged"
>>>>>>
>>>>>>
>>>>>> +1.  The warning message is not the place to be trying to explain all
>>>>>> the
>>>>>> details.
>>>>>
>>>>>
>>>>> OK, updated patch attached.
>>>>
>>>>
>>>> Patch applied.
>>>
>>>
>>> I only just noticed this item when I read the release notes.  Should
>>> we bother warning when used on an unlogged table?
>>
>>
>> Not really; but I think the bigger question at this point is if we want to
>> change it this late in the game.
>
> Changing it even during beta looks acceptable to me. I think that it
> is mainly a matter to have a patch (here is one), and someone to push
> it as everybody here seem to agree that for UNLOGGED tables this
> warning has little sense.

I think you should be testing RelationNeedsWAL(), not the
relpersistence directly.  The same point applies for temporary
indexes.

-- 
Robert Haas
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