Re: Selectivity estimation for inet operators

From: Emre Hasegeli <emre(at)hasegeli(dot)com>
To: Dilip kumar <dilip(dot)kumar(at)huawei(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Andreas Karlsson <andreas(at)proxel(dot)se>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: Selectivity estimation for inet operators
Date: 2014-07-06 15:02:52
Message-ID: 20140706150252.GA31963@hasegeli.local
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Thank you for looking at it.

> In inet_his_inclusion_selec function,
> When the constant matches only the right side of the bucket, and if it’s a last bucket then it's never considered as partial match candidate.
> In my opinion, if it's not a last bucket then for next bucket it will become left boundary and this will be treated as partial match so no problem, but in-case of last bucket it can give wrong selectivity.
> Can't we consider it as partial bucket match if it is last bucket ?

Actually, in that case, the ratio for one value in the column is used.
I clarified the comment about it. I do not think it is common enough
case to make the function more complicated.

> Apart from that there is one spell check you can correct
> -- in inet_his_inclusion_selec comments
> histogram boundies -> histogram boundaries :)

I fixed it. New version attached. The debug log statements are also

Attachment Content-Type Size
inet-selfuncs-v6.patch text/plain 24.3 KB

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