Re: Should we warn against using too many partitions?

On Mon, 10 Jun 2019 at 20:11, Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
>
> On Sun, Jun 9, 2019 at 5:29 AM David Rowley
> > I also split this out into its own paragraph since it's talking about
> > something quite different from the previous paragraph.
>
> Did you miss to split? In v4 patches, I still see this point
> mentioned in the same paragraph that it was in before:

Not quite. I just changed my mind again after reading it through.
Since both paragraphs were talking about the number of partitions I
decided they should be the same paragraph after all.

> > I've reworded
> > this slightly and it now says "what will the implications be if in
> > several years you instead find yourself with a large number of small
> > customers."
>
> I suggest "consider the implications" in place of "what will the
> implications be...". Also a user may choose a particular design (one
> partition per customer) *because* of their business situation (small
> number of large customers), so I suggest linking the two clauses with
> "because". With these two changes, the whole sentence will read more
> connected, imho:

The disconnect there is on purpose. I don't really want to suggest
they chose to partition by customer because they have a small number
of large customers. The choice to partition by customer could well
have come from "customer_id = ..." always being present in WHERE
clauses and they may be fooled into thinking it's a good idea to
partition by that because of that fact. I'm hoping the text there
points out that it might not always be a good choice.

I have slightly reworded it to be a bit closer to your suggestion, but
I maintained the disconnect.

--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services