From: | "Bucky Jordan" <bjordan(at)lumeta(dot)com> |
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To: | "Joshua Marsh" <icub3d(at)gmail(dot)com>, <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Hints proposal |
Date: | 2006-10-12 16:40:13 |
Message-ID: | 78ED28FACE63744386D68D8A9D1CF5D4209C9A@MAIL.corp.lumeta.com |
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Lists: | pgsql-hackers pgsql-performance |
>What is it about hinting that makes it so easily breakable with new versions? I >don't have any experience with Oracle, so I'm not sure how they screwed logic like >this up.
I don't have a ton of experience with oracle either, mostly DB2, MSSQL and PG. So, I thought I'd do some googling, and maybe others might find this useful info.
Interesting quote: "In Oracle Applications development (11i apps - HR, CRM, etc) Hints are strictly forbidden. We find the underlying cause and fix it." and
"Hints -- only useful if you are in RBO and you want to make use of an access
path."
Maybe because I haven't had access to hints before, I've never been tempted to use them. However, I can't remember having to re-write SQL due to a PG upgrade either.
Oh, and if you want to see everything that gets broken/depreciated with new versions, just take a look at oracle's release notes for 9i and 10g. I particularly dislike how they rename stuff for no apparent reason (e.g. NOPARALLEL is now NO_PARALLEL - http://www.oracle-base.com/articles/10g/PerformanceTuningEnhancements10g.php)
At the very least, I agree it is important to separate the query (what data do I want) from performance options (config, indexes, hints, etc). The data I want doesn't change unless I have a functionality/requirements change. So I'd prefer not to have to go back and change that code just to tweak performance. In addition, this creates an even bigger mess for dynamic queries. I would be much more likely to consider hints if they could be applied separately.
- Bucky
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