Re: Table rewrites vs. pending AFTER triggers

Hi Gokul,

If you are saying that DDL should be auto-commit, yes, this really does
limit some use cases.

Transactional DDL is quite helpful for SQL generators, which need to avoid
leaving schema half-changed if the application crashes or there¹s a problem
with the database that causes a command to fail. SLONY is an example of
such a generator where transactional DDL would be helpful though I don¹t
know for a fact that SLONY uses it. We have used it in the past for
building queues in SQL, which required multiple schema changes for a single
queue.

In sum, it¹s much easier to implement such tools if you can do a set of
schema changes atomically. There are no doubt other use cases as well.

Cheers, Robert

On 1/2/08 11:04 PM, "Gokulakannan Somasundaram" <gokul007(at)gmail(dot)com> wrote:

> Is there why we allow DDLs inside a transaction and allow it to be rolled
> back? If we commit the previous transaction, as soon as we encounter a DDL,
> and commit the DDL too (without waiting for commit) will it be affecting some
> use cases?
>
> I actually mean to say that DDLs can be declared as self-committing. That
> would get rid of these exceptions.
>
> Am i missing something?
>
> Thanks,
> Gokul.
>
> On Jan 3, 2008 12:02 AM, Andrew Dunstan < adunstan(at)postgresql(dot)org> wrote:
>>
>>
>> Simon Riggs wrote:
>>> On Tue, 2008-01-01 at 16:09 -0500, Tom Lane wrote:
>>>
>>>
>>>> Paranoia would
>>>> suggest forbidding *any* form of ALTER TABLE when there are pending
>>>> trigger events, but maybe that's unnecessarily strong.
>>>>
>>>
>>> That works for me. Such a combination makes no sense, so banning it is
>>> the right thing to do.
>>>
>>>
>>
>> +1. Doesn't make much sense to me either.
>>
>> cheers
>>
>> andrew
>>
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>

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Robert Hodges, CTO, Continuent, Inc.
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