Re: [Proposal] Allow users to specify multiple tables in VACUUM commands

On 5 September 2017 at 02:16, Michael Paquier <michael.paquier@gmail.com> wrote:
> On Mon, Sep 4, 2017 at 11:47 PM, Bossart, Nathan <bossartn@amazon.com> wrote:
>> I've made this change in v14 of the main patch.
>>
>> In case others had opinions regarding the de-duplication patch, I've
>> attached that again as well.
>
> +   /*
> +    * Create the relation list in a long-lived memory context so that it
> +    * survives transaction boundaries.
> +    */
> +   old_cxt = MemoryContextSwitchTo(AutovacMemCxt);
> +   rangevar = makeRangeVar(tab->at_nspname, tab->at_relname, -1);
> +   rel = makeVacuumRelation(rangevar, NIL, tab->at_relid);
> +   rel_list = list_make1(rel);
> +   MemoryContextSwitchTo(old_cxt);
> That's way better, thanks for the new patch.
>
> So vacuum_multiple_tables_v14.patch is good for a committer in my
> opinion. With this patch, if the same relation is specified multiple
> times, then it gets vacuum'ed that many times. Using the same column
> multi-times results in an error as on HEAD, but that's not a new
> problem with this patch.
>
> So I would tend to think that the same column specified multiple times
> should cause an error, and that we could let VACUUM run work N times
> on a relation if it is specified this much. This feels more natural,
> at least to me, and it keeps the code simple.

ISTM there is no difference between
  VACUUM a, b
and
  VACUUM a; VACUUM b;

If we want to keep the code simple we must surely consider whether the
patch has any utility.

-- 
Simon Riggs                http://www.2ndQuadrant.com/
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