Re: SQL/MED - core functionality
От | Simon Riggs |
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Тема | Re: SQL/MED - core functionality |
Дата | |
Msg-id | 1293030016.1193.28081.camel@ebony обсуждение исходный текст |
Ответ на | Re: SQL/MED - core functionality (Andrew Dunstan <andrew@dunslane.net>) |
Ответы |
Re: SQL/MED - core functionality
Re: SQL/MED - core functionality |
Список | pgsql-hackers |
On Wed, 2010-12-22 at 09:03 -0500, Andrew Dunstan wrote: > Answering a few of your questions Many thanks. > > 7. Why does ANALYZE skip foreign tables? Surely its really important we > > know things about a foreign table, otherwise we are going to optimize > > things very badly. > > Quite apart from other reasons, such as possible ephemerality of the > data, the difficulty of taking a reasonable random sample from an > arbitrary foreign data source seems substantial, and we surely don't > want ANALYSE to have to run a full sequential scan of a foreign data source. I think we need something that estimates the size of a table, at least, otherwise queries will be completely un-optimised. > > 10. Can a foreign table be referenced by a FK? > > I don't see how it can be. There would be no unique index to use. That answers another question also. Still many unanswered. -- Simon Riggs http://www.2ndQuadrant.com/books/PostgreSQL Development, 24x7 Support, Training and Services
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