Re: Index Skip Scan
| От | Andy Fan |
|---|---|
| Тема | Re: Index Skip Scan |
| Дата | |
| Msg-id | CAKU4AWqqsagFb=J4bu5YfxokZvmqb_hGDZFtimfSzNLBFthUuQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Index Skip Scan (David Rowley <dgrowleyml@gmail.com>) |
| Ответы |
Re: Index Skip Scan
|
| Список | pgsql-hackers |
I think the UniqueKeys may need to be changed from using
EquivalenceClasses to use Exprs instead.
When I try to understand why UniqueKeys needs EquivalenceClasses,
see your comments here. I feel that FuncExpr can't be
used to as a UniquePath even we can create unique index on f(a)
and f->strict == true. The reason is even we know a is not null,
f->strict = true. it is still be possible that f(a) == null. unique index
allows more than 1 null values. so shall we move further to use varattrno
instead of Expr? if so, we can also use a list of Bitmapset to present multi
unique path of a single RelOptInfo.
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