| From: | Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com> |
|---|---|
| To: | atorikoshi <torikoshi_atsushi_z2(at)lab(dot)ntt(dot)co(dot)jp> |
| Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Fix a typo in README.dependencies |
| Date: | 2017-06-05 12:24:08 |
| Message-ID: | CAFjFpRd03YojT4wyuDcjhCfYuygfWfnt68XGn2CKv=rcjRCtTA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Jun 5, 2017 at 8:22 AM, atorikoshi
<torikoshi_atsushi_z2(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> Hi,
>
> I found below formula to compute selectivities, but
> I think the last Probability 'P(b=?)' should be 'P(c=?)'.
>
>> P(a=?,b=?,c=?) = P(a=?,b=?) * (d + (1-d)*P(b=?))
>
>
> Attached patch fixes it, and it also adds some spaces
> following another formula which is on line 86 and
> computes P(a=?, b=?).
Agree. Also using "d" for "degree of functional dependence (b=>c) as
well is confusing. We are already using "d" for "degree of functional
dependence (a=>b). Here' patch to use "d'" instead of "d".
--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company
| Attachment | Content-Type | Size |
|---|---|---|
| fix_typo_in_README_v2.dependencies | application/octet-stream | 680 bytes |
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