Should 'sum(mvf)' read 'sum(mcv)'...?
От | PG Doc comments form |
---|---|
Тема | Should 'sum(mvf)' read 'sum(mcv)'...? |
Дата | |
Msg-id | 166112292492.654.5377188452604176150@wrigleys.postgresql.org обсуждение исходный текст |
Ответы |
Re: Should 'sum(mvf)' read 'sum(mcv)'...?
|
Список | pgsql-docs |
The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/14/row-estimation-examples.html Description: About halfway down this page https://www.postgresql.org/docs/current/row-estimation-examples.html we see the following formula for calculating selectivity: > selectivity = (1 - sum(mvf))/(num_distinct - num_mcv) And just below the formula we see the explanatory sentence saying: > That is, add up all the frequencies for the MCVs and subtract them from one, ... It appears the above sentence is referring to the "(1 - sum(mvf))" portion of the formula, however I am not sure what "mvf" is referring to there...shouldn't it be "(1 - sum(mcv))" in order to match what the explanatory sentence is saying? Many thanks, Eric Mutta.
В списке pgsql-docs по дате отправления: