| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | amit sehas <cun23(at)yahoo(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Cursor behavior |
| Date: | 2011-12-21 16:43:22 |
| Message-ID: | CA+TgmoaYmoXYeWxB3ZF4oEG73WunxyiBggA1p9X-kcpQimNyvQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Dec 15, 2011 at 4:15 PM, amit sehas <cun23(at)yahoo(dot)com> wrote:
> I had a question about the cursor internals implementation. When you Fetch next 'n' results without moving the cursors, is this kind of functionality implemented by firstly executing the whole query and then moving the cursor over the results, or are the movements done on active database lookups, moving forward and backward...
I think it depends on the query. For example, I believe that a query
involving writeable CTEs will be run to completion before returning
any results, but I believe that a seqscan will not.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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