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help / color / mirror / Atom feedFrom: Tom Lane <[email protected]>
To: Justin Pryzby <[email protected]>
Cc: [email protected]
Subject: Re: overestimate on empty table
Date: Sat, 11 Nov 2017 12:43:04 -0500
Message-ID: <[email protected]> (raw)
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Justin Pryzby <[email protected]> writes:
> On Fri, Nov 10, 2017 at 04:19:41PM -0500, Tom Lane wrote:
>> One idea is to say that relpages = reltuples = 0 is only the state that
>> prevails for a freshly-created table, and that VACUUM or ANALYZE should
>> always set relpages to at least 1 even if the physical size is zero.
>> Dunno if that would confuse people.
> What about adding && rel->rd_rel->reltuples==0, and make VACUUM/ANALYZE instead
> set only reltuples=1, since that's already done at costsize.c: clamp_row_est()
> and therefor no additional confusion?
1 tuple in 0 pages is a physically impossible situation, so I'm quite
sure that way *would* confuse people.
regards, tom lane
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