| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Jian Guo <gjian(at)vmware(dot)com>, Zhenghua Lyu <zlyu(at)vmware(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: On disable_cost |
| Date: | 2024-03-12 21:18:09 |
| Message-ID: | 1824441.1710278289@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
David Rowley <dgrowleyml(at)gmail(dot)com> writes:
> So maybe the fix could be to set disable_cost to something like
> 1.0e110 and adjust compare_path_costs_fuzzily to not apply the
> fuzz_factor for paths >= disable_cost. However, I wonder if that
> risks the costs going infinite after a couple of cartesian joins.
Perhaps. It still does nothing for Robert's point that once we're
forced into using a "disabled" plan type, it'd be better if the
disabled-ness didn't skew subsequent planning choices.
On the whole I agree that getting rid of disable_cost entirely
would be the way to go, if we can replace that with a separate
boolean without driving up the cost of add_path too much.
regards, tom lane
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