Re: Should heapam_estimate_rel_size consider fillfactor?

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От Corey Huinker
Тема Re: Should heapam_estimate_rel_size consider fillfactor?
Дата
Msg-id CADkLM=eSFK2dD8sR7gf7WP3WeS25yvCwWHPEqGmXfRu50HRQkA@mail.gmail.com
обсуждение исходный текст
Ответ на Should heapam_estimate_rel_size consider fillfactor?  (Tomas Vondra <tomas.vondra@enterprisedb.com>)
Ответы Re: Should heapam_estimate_rel_size consider fillfactor?  (Peter Eisentraut <peter@eisentraut.org>)
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Дерево обсуждения
So maybe we should make table_block_relation_estimate_size smarter to
also consider the fillfactor in the "no statistics" branch, per the
attached patch.

I like this a lot. The reasoning is obvious, the fix is simple,it doesn't upset any make-check-world tests, and in order to get a performance regression we'd need a table whose fillfactor has been changed after the data was loaded but before an analyze happens, and that's a narrow enough case to accept.

My only nitpick is to swap
(usable_bytes_per_page * fillfactor / 100) / tuple_width
with
(usable_bytes_per_page * fillfactor) / (tuple_width * 100)

as this will eliminate the extra remainder truncation, and it also gets the arguments "in order" algebraically.


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