tag:blogger.com,1999:blog-4102670365555651344.post394641029779041197..comments2023-05-20T11:20:18.653+03:00Comments on antonoal's oracle tips: How CBO calculates cardinality (Part 1)Alexandr Antonovhttp://www.blogger.com/profile/16541743594136378799noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-4102670365555651344.post-62507744082088339462013-09-13T11:56:02.525+03:002013-09-13T11:56:02.525+03:00Спасибо!Спасибо!Anonymoushttps://www.blogger.com/profile/04957745500614631321noreply@blogger.comtag:blogger.com,1999:blog-4102670365555651344.post-42547860213943039082013-09-12T20:17:24.378+03:002013-09-12T20:17:24.378+03:00Read num_rows as number of not null rows and every...Read num_rows as number of not null rows and everything will come into place.<br />I didn't try to be pedantic about what I was writing, I was just trying to give a flavour of what could be happening under the hood of CBO in some situations.Alexandr Antonovhttps://www.blogger.com/profile/16541743594136378799noreply@blogger.comtag:blogger.com,1999:blog-4102670365555651344.post-14393138568270996512013-09-11T11:14:13.550+03:002013-09-11T11:14:13.550+03:00План показывает 1 но если считать по формуле Cardi...План показывает 1 но если считать по формуле Cardinality = user_tables.num_rows / user_tab_col_statistics.num_distinct получается 213Anonymoushttps://www.blogger.com/profile/04957745500614631321noreply@blogger.comtag:blogger.com,1999:blog-4102670365555651344.post-44769388754230482572013-09-11T10:56:57.039+03:002013-09-11T10:56:57.039+03:00Привет спасибо за статью. У меня есть select * fro...Привет спасибо за статью. У меня есть select * from emp where f_name_r2 = 'Анатолий Фёдорович'; колонка f_name_r2 без гистограммы всего в таблице 8928 строк, Num distinct = 42, Num Nulls = 8886. Подскажите пожалуйста как посчитать cardinality?Anonymoushttps://www.blogger.com/profile/04957745500614631321noreply@blogger.comtag:blogger.com,1999:blog-4102670365555651344.post-7936688012477369402010-01-26T11:19:40.090+02:002010-01-26T11:19:40.090+02:00Thanks for you interesting.
I'm going to put ...Thanks for you interesting.<br /><br />I'm going to put the BETWEEN operation findings into the second part of the article which I hope to post within the week.Alexandr Antonovhttps://www.blogger.com/profile/16541743594136378799noreply@blogger.comtag:blogger.com,1999:blog-4102670365555651344.post-23788879018753371242010-01-25T13:34:59.380+02:002010-01-25T13:34:59.380+02:00Antonol,
Just came across your post. Nice analysi...Antonol,<br /><br />Just came across your post. Nice analysis. Thanks. Do you know how the cardinality is calculated (now) for BETWEEN operator ?Narendrahttps://www.blogger.com/profile/14645699853364658640noreply@blogger.com