Re: vacuumdb -f and -j options (was Question / requests.)

On Sat, Oct 8, 2016 at 5:52 PM, Michael Paquier
<michael(dot)paquier(at)gmail(dot)com> wrote:
> On Sat, Oct 8, 2016 at 9:12 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> On Fri, Oct 7, 2016 at 10:16 PM, Alvaro Herrera
>> <alvherre(at)2ndquadrant(dot)com> wrote:
>>> Robert Haas wrote:
>>>> On Wed, Oct 5, 2016 at 10:58 AM, Francisco Olarte
>>>> I don't know, but it seems like the documentation for vacuumdb
>>>> currently says, more or less, "Hey, if you use -j with -f, it may not
>>>> work!", which seems unacceptable to me. It should be the job of the
>>>> person writing the feature to make it work in all cases, not the job
>>>> of the person using the feature to work around the problem when it
>>>> doesn't.
>>>
>>> The most interesting use case of vacuumdb is lazy vacuuming, I think, so
>>> committing that patch as it was submitted previously was a good step
>>> forward even if it didn't handle VACUUM FULL 100%.
>>>
>>> I agree that it's better to have both modes Just Work in parallel, which
>>> is the point of this subsequent patch. So let's move forward. I
>>> support Francisco's effort to make -f work with -j. I don't have a
>>> strong opinion on which of the various proposals presented so far is the
>>> best way to implement it, but let's figure that out and get it done.
>>>
>>
>> After reading Francisco's proposal [1], I don't think it is directly
>> trying to make -f and -j work together. He is proposing to make it
>> work by providing some new options. As you are wondering upthread, I
>> think it seems reasonable to disallow -f with parallel vacuuming if no
>> tables are specified.
>
> Instead of restricting completely things, I'd like to think that being
> able to make both of them work together is the right move at the end.
>

Sure, if somebody can come up with a patch which can safely avoid the
deadlock when both -f and -j options are used, then we should go that
way. Otherwise we can block those options to be used together rather
than just have a note in docs.

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