Re: Should we add GUCs to allow partition pruning to be disabled?

On Mon, Mar 11, 2019 at 12:30 AM Amit Langote
<Langote_Amit_f8@lab.ntt.co.jp> wrote:
> Now the question is where to put this text?  Currently, we have:
>
> 5.10. Table Partitioning
>   5.10.1. Overview
>   5.10.2. Declarative Partitioning
>   5.10.3. Implementation Using Inheritance
>   5.10.4. Partition Pruning
>   5.10.5. Partitioning and Constraint Exclusion
>
> Should we add 5.10.6 Notes for the above "note", or should it be stuffed
> under one of the existing sub-headings?

I think it should be added to one of the existing sub-headings.  I
suggest adding it to the end of 5.10.1 and rephrasing it so that it
makes clearer the distinction between what will happen with
inheritance and what will happen with table partitioning, e.g.

When using either declarative partitioning or table inheritance,
partitioning hierarchies with more than a few hundred partitions are
not currently recommended. Larger partition hierarchies may incur long
planning time, and especially in the case of UPDATE and DELETE,
excessive memory usage.  When inheritance is used, see also the
limitations described in Section 5.10.5, Partitioning and Constraint
Exclusion.

-- 
Robert Haas
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