Re: planstats.sgml

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От Tatsuo Ishii
Тема Re: planstats.sgml
Дата
Msg-id 20160216.160106.942751076136207061.t-ishii@sraoss.co.jp
обсуждение исходный текст
Ответ на Re: planstats.sgml  (Tatsuo Ishii <ishii@postgresql.org>)
Ответы Re: planstats.sgml  (Mark Kirkwood <mark.kirkwood@catalyst.net.nz>)
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>> Tatsuo Ishii <ishii@postgresql.org> writes:
>>> While reading planstats.sgml, I encounted a sentence which I don't
>>> understand.
>> 
>>>     These numbers are current as of the last <command>VACUUM</> or
>>>     <command>ANALYZE</> on the table.  The planner then fetches the
>>>     actual current number of pages in the table (this is a cheap operation,
>>>     not requiring a table scan).  If that is different from
>>>     <structfield>relpages</structfield> then
>>>     <structfield>reltuples</structfield> is scaled accordingly to
>>>     arrive at a current number-of-rows estimate.  In this case the value of
>>>     <structfield>relpages</structfield> is up-to-date so the rows estimate is
>>>     the same as <structfield>reltuples</structfield>.
>> 
>>> I don't understand the last sentence (In this case...). For me it
>>> seems it is talking about the case when replages is not different from
>>> what the planner fetches from the table. If so, why "In this case"?
>> 
>> I think what it meant is "In the example above, ...".  Feel free to
>> change it if you think that is clearer.
> 
> Oh, I see. I'm going to change "In this case" to "In the example above".

Done.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp



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