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11985 Views 3 Replies Latest reply: Feb 22, 2010 9:13 AM by Gib RSS
Gib New Enzee 4 posts since
Feb 19, 2010
Currently Being Moderated

Feb 19, 2010 5:09 PM

Query takes longer to run in Netezza than our OTP Oracle DB

I appologize in advance if this is the wrong part of the forum to post tuning questions on but I am brand spanking new to Netezza.  Let me know where to post it if so and thanks in advance.

 

I have a query that is taking 1400+ seconds to return in Netezza but in Oracle it completes in only 150 seconds.  I am a complete noobie with Netezza and no training but tasked with reducing query time on it. They are using Netezza as a copy of our prod to do the reporting out of and performance has been as expected but someone formulated a query that is not performing. Since I am told that you don't do Indexes on Netezza and Netezza is made for LARGE volumes of data processing, is it possible that this querys quantity of rows returned makes it faster to do on a regular oracle db with indexes?

 

Is there ANY kind of tuning to be done and is there a manual anywhere to download on the subject of query performance on this appliance?

 

Thanks for taking the time to politely reply to this post.

 

Gib

  • Shawn Fox Enzee Exraordinaire 1,326 posts since
    Aug 15, 2006

    Your best bet is to log an issue with support and/or contact your techincal account manager.  There are certainly a few odd queries which run better on Oracle, but generally those would be cases where your query is only returning a few records (index lookup in Oracle).  Since the query takes 120 seconds in Oracle, I'd bet you can get it to run much faster than that in Netezza but you might have to rewrite the query.

  • David Birmingham Active Enzee 426 posts since
    Sep 24, 2007

    Strictly speaking we don't tune queries before we tune the data

     

    First things first - Check your distribution on the nz admin gui and make sure the data is evenly distributed (no spikes)

     

    secondly - make sure you are not using a distribution like a date that will focus all the work on one SPU

     

    thirdly, if any secondary tables are involved, distribute them on the same key (if possible)

     

    lastly, simplify your query - most of the time an Oracle-centric query is tuned to make the machine do things in a certain order, but query tuning is not applicable in Netezza. You can make a bad query run better but you cannot make a good query run significantly better than it already is. In Netezza, power is in the physics - how you organize and distribute the data, not in the query.

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