Re: Very specialised query
| От | Віталій Тимчишин |
|---|---|
| Тема | Re: Very specialised query |
| Дата | |
| Msg-id | 331e40660903311411k532df0e3jeeffdb184adba9e6@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Very specialised query (Matthew Wakeling <matthew@flymine.org>) |
| Ответы |
Re: Very specialised query
|
| Список | pgsql-performance |
The outer nested join has the VALUES as the main loop, and the complicated join as the leaf. So, the complicated overlap-finding join gets run twice.
That's weird. What do you have as statistics target? Planner is incorrect few orders of magnitude, so increasing it may help.
BTW: One of constraints is redundant l1.start <= l2.start implies l1.start <= l2.end, so latter can be removed as for me.
Oh, there's also the great big sort and unique, but I think I can get rid of that.
As far as I can see, duplicates will occur if and only if l1.start == l2.start && l1.end == l2.end.
That can be easily filtered by adding "where n=1 or l1.start != l2.start or l1.end != l2.end" to outer select.
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