Re: Indexes not allowed on (read-only) views: Why?
От | Merlin Moncure |
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Тема | Re: Indexes not allowed on (read-only) views: Why? |
Дата | |
Msg-id | CAHyXU0xD6Phx5o04n2Q9uK-VdsbRMHNeHGg-20TFp4LTgV2WbA@mail.gmail.com обсуждение исходный текст |
Ответ на | Indexes not allowed on (read-only) views: Why? (Stefan Keller <sfkeller@gmail.com>) |
Список | pgsql-general |
On Fri, Sep 16, 2011 at 4:47 PM, Stefan Keller <sfkeller@gmail.com> wrote: > A (read-only) view should behave like a table, right? > >> CREATE INDEX t1_idx ON t1 (rem); > ERROR: »v1« not a table > SQL state: 42809 > > => Why should'nt it be possible to create indexes on views in PG? > > An index on a view can speed up access to the tuples underlying. And > "indexed views" could be a method of storing the result set of the > view in the database, thereby reducing the overhead of dynamically > building the result set. An "indexed view" should automatically adapt > modifications made to the data in the base tables. So, there is some > overhead here, but this is ok when speed in retrieving results > outweighs the cost... > > And there is no practical reason since SQL Server can do it! See > "Creating Indexes on Views" > http://msdn.microsoft.com/en-us/library/aa933124%28v=sql.80%29.aspx implementation across databases is different. in postgres, views are essentially macros, thus there is no data to index. merlin
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