Comments on: Sample Clause http://jonathanlewis.wordpress.com/2010/03/12/sample-clause/ Just another Oracle weblog Thu, 23 May 2013 12:47:17 +0000 hourly 1 http://wordpress.com/ By: Blogroll Report 05/02/2010 – 12/03/2010 « Coskan’s Approach to Oracle http://jonathanlewis.wordpress.com/2010/03/12/sample-clause/#comment-36084 Fri, 23 Apr 2010 01:08:40 +0000 http://jonathanlewis.wordpress.com/?p=3345#comment-36084 [...] 21-How does sample clause work? Jonathan Lewis-Sample Clause [...]

]]> By: Jonathan Lewis http://jonathanlewis.wordpress.com/2010/03/12/sample-clause/#comment-35822 Sat, 20 Mar 2010 13:08:01 +0000 http://jonathanlewis.wordpress.com/?p=3345#comment-35822 Kyle,

Thanks for the comment. From memory there was a time when the sample clause could only work with a single table query, and then Oracle did something to extend it. I never got around to testing it, though. I would be quite surprised if it worked well given the conflicting requirements of relational integrity and random selection.

]]> By: Kyle Hailey http://jonathanlewis.wordpress.com/2010/03/12/sample-clause/#comment-35786 Tue, 16 Mar 2010 22:18:45 +0000 http://jonathanlewis.wordpress.com/?p=3345#comment-35786 Nice clear analysis (as always) thanks.
I’ve wanted to use this type functionality test out query plans on subsets of the real tables to limit the running result set sizes of a execution plan. Of course I can use CTAS to create smaller versions of the tables but that’s resource intensive. It’s so tempting to think there might be a way to accomplish the same thing with some limiting clause like the sample clause. Of course the sample clause is problematic in its own ways but still wondering if there is any way to do it. I started to play with creating views that had the sample clause in them. As I recall the queries worked but I didn’t get far enough to determine whether the timing and resource results were worth anything. If I go back and try some more I will at least know of some of the other gotchas.

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