> "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."
1. My understanding of the above paragraph is that for the same view and
different users, the proleakproof=false attribute of the function will not lead
to inconsistent plans, but my actual test result is that proleakproof=false
will lead to inconsistent plans。
2. What's the reason about the function timestamp_gt_timestampz may cause data
leakage? Can you explain how it causes data leakage?
------------------------------------------------------------------
发件人：Laurenz Albe <laurenz.a...@cybertec.at>
发送时间：2022年10月17日(星期一) 15:20
收件人：qiumingcheng <qiumingch...@aliyun.com>; Tom Lane <t...@sss.pgh.pa.us>
抄 送：Julien Rouhaud <rjuju...@gmail.com>; pgsql-general
<pgsql-general@lists.postgresql.org>
主 题：Re: 回复：回复：A question about leakproof
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
