Re: [HACKERS] DROP SUBSCRIPTION hangs if sub is disabled in the sametransaction

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  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/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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