Re: Review remove {join,from}_collapse_limit, add enable_join_ordering - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Review remove {join,from}_collapse_limit, add enable_join_ordering
Date
Msg-id 23200.1247749982@sss.pgh.pa.us
Whole thread Raw
In response to Review remove {join,from}_collapse_limit, add enable_join_ordering  (Andres Freund <andres@anarazel.de>)
Responses Re: Review remove {join,from}_collapse_limit, add enable_join_ordering  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
Andres Freund <andres@anarazel.de> writes:
> The queries on the second reporting schema unfortunately are different. Its the 
> one were I copied the crazy example I attached in the original thread.
> With geqo=off a good part of the queries used daily use too much memory to plan 
> sensibly and geqo=on outright fails with: 
> "Error: Failed to make a valid plan"
> on some.

We're not going to be able to fix this unless you show us examples.

> Noticeable even some plans which were plannable in reasonable time before now 
> are problematic with enable_join_ordering=false!

And this even more so --- it doesn't make any sense at all.

> So, while I think the changes are principally a good idea, as 
> {from,join}_collapse_limit are a bit confusing options, I personally! do not 
> think geqo is ready for it today, especially as the benefit is relatively 
> small.

In general I think that any such bugs are there anyway and need to be
fixed anyway.
        regards, tom lane


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