Re: explain plans with information about (modified) gucs

On 1/1/19 6:48 PM, Pavel Stehule wrote:
>
>
> út 1. 1. 2019 v 18:39 odesílatel Tomas Vondra
> <tomas(dot)vondra(at)2ndquadrant(dot)com <mailto:tomas(dot)vondra(at)2ndquadrant(dot)com>> napsal:
>
> Attached is v4, changing how GUCs are picked for inclusion on the query
> plans. Instead of picking the GUCs based on group and/or explicitly, a
> new GUC_EXPLAIN flag is used for that.
>
> I went through GUCs defined in guc.c and marked those in QUERY_TUNING*
> groups accordingly, with the exception of default_statistics_target
> because that seems somewhat useless without showing the value used to
> actually analyze the table (and/or columns).
>
> I've also included a couple of other GUCs, that I find to be relevant:
>
> - parallel_leader_participation
> - max_parallel_workers_per_gather
> - max_parallel_workers
> - search_path
> - effective_io_concurrency
> - work_mem
> - temp_buffers
> - plan_cache_mode
>
>
> when plan_cache_mode is auto, you know maybe too less executed query.
> Maybe you can read somewhere if plan was custom or generic.
>

This patch is about showing GUCs, not such additional internal info.
Also, you'll see the plan actually used.

>
> I think this covers the interesting GUCs pretty well, although perhaps I
> missed something.
>
>
> seq_page_cost, random_page_cost, from_collapse_limit,
> join_collapse_limit, ... enable_***
>

All these GUCs are included, of course.

--
Tomas Vondra http://www.2ndQuadrant.com
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