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Number of logical reads very different between 2 supposed identical environments

  • November 28, 2016 at 5:45 am

    #1914688

    Hi all,

    Thanks for all your investigations and suggestions. 🙂

    Since I've replaced XML conversions (necessary with former "SQL Server 2008" but useless and costly with 2014 release) with standard CAST, all things are better.

    I've also simplified views (1 instead of 2).

    Now, performances are quite similar berween UAT and PROD.

    I didn't create any index yet.

    From my understanding of your explainations, optimizer uses kind of internal indexes based on statistics

    ...but to be sure to get similar results in different environments, it should be better to explicitly create indexes, shouldn't it ?

    Regards,

    Steph.

  • November 29, 2016 at 1:23 am

    #1914875

    polytropic2310 (11/28/2016)

    From my understanding of your explainations, optimizer uses kind of internal indexes based on statistics

    That's a misunderstanding. SQL Server doesn't have any internal indexes. If you do not create any indexes, then the information is stored completely unordered and unindexed; and that will always affect performance (and allmost always ina negative way).

    Hugo Kornelis, SQL Server/Data Platform MVP (2006-2016)
    Visit my SQL Server blog: https://sqlserverfast.com/blog/
    SQL Server Execution Plan Reference: https://sqlserverfast.com/epr/

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