Re: [HACKERS] Multi column range partition table

On 2017/07/07 4:55, Dean Rasheed wrote:
> On 5 July 2017 at 18:07, Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
>> So if we were to go for maximum flexibility and compatibility with
>> Oracle, then perhaps what we would do is more like the original idea
>> of UNBOUNDED ABOVE/BELOW, except call them MINVALUE and MAXVALUE,
>> which conveniently are already unreserved keywords, as well as being
>> much shorter. Plus, we would also relax the constraint about having
>> finite values after MINVALUE/MAXVALUE.
>>
> So I know that I have flip-flopped a few times on this now, but I'm
> now starting to think that this approach, replacing UNBOUNDED with
> MINVALUE and MAXVALUE is the best way to go, along with permitting
> finite values after MINVALUE/MAXVALUE.

Sure.

> This gives the greatest flexibility, it's not too verbose, and it
> makes it easy to define contiguous sets of partitions just by making
> the lower bound of one match the upper bound of another.
> 
> With this approach, any partition bounds that Oracle allows are also
> valid in PostgreSQL, not that I would normally give too much weight to
> that, but it is I think quite a nice syntax. Of course, we also
> support things that Oracle doesn't allow, such as MINVALUE and gaps
> between partitions.

Agreed.  MINVALUE/MAXVALUE seems like a good way forward.

> Parts of the patch are similar to your UNBOUNDED ABOVE/BELOW patch,
> but there are a number of differences -- most notably, I replaced the
> "infinite" boolean flag on PartitionRangeDatum with a 3-value enum and
> did away with all the DefElem nodes and the associated special string
> constants being copied and compared.

That's better.

> However, this is also an incompatible syntax change, and any attempt
> to support both the old and new syntaxes is likely to be messy, so we
> really need to get consensus on whether this is the right thing to do,
> and whether it *can* be done now for PG10.

+1 to releasing this syntax in PG 10.

The patch looks generally good, although I found and fixed some minor
issues (typos and such).  Please find attached the updated patch.

Thanks,
Amit

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