What is a cursor EXACTLY?(internals question)

From: Norman Dunbar <Norman.Dunbar_at_lfs.co.uk>
Date: Wed, 29 Jan 2003 08:39:35 -0000
Message-ID: <E2F6A70FE45242488C865C3BC1245DA7033C0CA8@lnewton.leeds.lfs.co.uk>

Morning Ryan,

Here are a couple of definitions :

Cursor : That little thingy on the screen where the next letter I type will go.

Cursor : Me, when things don't work properly.

Cursor : CURrent Set Of Records. (at least it was in IDMS(X) hierarchical databases that I used to work with !)

As far as I've been able to find out, the last meaning is accurate in Oracle too. I'm also led to believe (by an Oracle Training instructor) that Oracle holds the results of a query in a reserved area of memory - like a memory table - and you read from that. Now, bearing in mind that not all instructors are as good as others, I leave it for others more knolegable than I am to comment.

OPEN_CURSORS defines the maximum amount of cursors your users can *each* can have open, and each one needs about 256 bytes of Shared Pool - I presume that that is just for overhead and doesn't include the results set.

Cheers,
Norman.

PS. Oracle is written in 'C' as far as I know, and not C++ - I sit to be corrected.

Norman Dunbar
Database/Unix administrator
Lynx Financial Systems Ltd.
mailto:Norman.Dunbar_at_LFS.co.uk

Tel: 0113 289 6265
Fax: 0113 289 3146
URL: http://www.Lynx-FS.com


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Received on Wed Jan 29 2003 - 02:39:35 CST