Re: DROP SUBSCRIPTION hangs if sub is disabled in the same transaction

On 9/14/17 08:23, Alvaro Herrera wrote:
> Peter Eisentraut wrote:
>> On 9/13/17 09:56, Alvaro Herrera wrote:
>>> Tom Lane wrote:
>>>> Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> writes:
>>>
>>>>> - Disallow DROP SUBSCRIPTION in a transaction under certain
>>>>> circumstances, for example if a transaction has previously manipulated
>>>>> the same subscription.
>>>
>>>> ISTM the second of those (refuse to drop an in-use subscription) is
>>>> by far the least surprising behavior.
>>>
>>> +1 for that option. IIRC this has precedent for other object types such
>>> as tables, where we refuse some action if we have already operated on
>>> the table in the same transaction.
>>
>> What are some examples of such behavior?
>
> Search for CheckTableNotInUse() callers.

That one uses the relcache refcount, so we can't use that mechanism
here. I think we need something based on xmin. The enum code has
something like it, but I don't understand the details.

--
Peter Eisentraut http://www.2ndQuadrant.com/
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