Re: 回复:回复:A question about leakproof

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От Laurenz Albe
Тема Re: 回复:回复:A question about leakproof
Дата
Msg-id 9e253a3226436819f0aaf59fb82137477d9f5a78.camel@cybertec.at
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Ответ на 回复:回复:A question about leakproof  ("qiumingcheng" <qiumingcheng@aliyun.com>)
Ответы 回复:回复:回复:A question about leakproof  ("qiumingcheng" <qiumingcheng@aliyun.com>)
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On Mon, 2022-10-17 at 13:17 +0800, qiumingcheng wrote:
> > you seem to be imagining that changes in a query's plan on the basis of changes
> > in collected statistics have something to do with this.  They do not.
>
> Sorry, I may not fully understand what you mean. I mean that after my tests,
> the execution results of this SQL (explain select * from tb_a_date_v1) execution plan
> are different under different users, which is really related to the parameter proleakproof.

That's the idea behind leakproof: if a function is not leakproof, the optimizer
will not move it "inside" the view definition.  Then the function is evaluated only
after the view definition.  That may very well lead to a slower execution plan,
because it cannot use certain indexes on the underlying tables.

It is the price you have to pay for good security.

Yours,
Laurenz Albe



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