Forum Replies Created

Viewing 15 posts - 2,671 through 2,685 (of 49,552 total)

  • RE: Actual and Estimates That old conversation.

    Lynn Pettis (8/9/2016)

    Overly complex queries where the optimizer doesn't have time to properly evaluate plans.

    That'll get poor plans, not inaccurate row estimations.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 9, 2016 at 9:30 am

    #1894571

  • RE: Check sum in backup

    https://www.simple-talk.com/sql/backup-and-recovery/backup-verification-tips-for-database-backup-testing/

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 9, 2016 at 9:29 am

    #1894570

  • RE: Actual and Estimates That old conversation.

    A large number of things.

    Lack of statistics

    Conversions or functions on columns

    Table variables (including multi-statement UDFs)

    Variables in predicates

    Plans being reused for executions with different parameters

    Generalising queries (eg the Column = @Parameter...

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 9, 2016 at 9:25 am

    #1894566

  • RE: explain composite index structure and work? How B Tree for composite index work internally?

    Pretty much, yes.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 9, 2016 at 4:44 am

    #1894485

  • RE: Rename Column with comma

    What are the exact errors you're getting?

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 8, 2016 at 9:00 am

    #1894366

  • RE: explain composite index structure and work? How B Tree for composite index work internally?

    Please don't post multiple threads for the same question.

    No replies here. Replies to http://www.sqlservercentral.com/Forums/Topic1807856-3077-1.aspx

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 8, 2016 at 8:51 am

    #1894362

  • RE: explain composite index structure and work? How B Tree for composite index work internally?

    By 'composite', I assume you mean a multi-column index.

    If so, there's no calculations and the values are stored just as they would be with a single column index.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 8, 2016 at 8:49 am

    #1894361

  • RE: should we use json or xml in sqlserver.

    Jeff Moden (8/7/2016)

    For example (and I'll admit I've not looked it up in the last 2 months or so), I'm pretty sure that the use of NOLOCK hasn't actually been...

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 7, 2016 at 12:35 pm

    #1894232

  • RE: Query Execution Time

    The times for the individual statements within the procedure, not time to read tables.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 7, 2016 at 12:33 pm

    #1894231

  • RE: Query Execution Time

    VastSQL (8/7/2016)

    SQL Server Execution Times:

    CPU time = 15 ms, elapsed time = 76 ms.

    That's the total time for the procedure.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 7, 2016 at 5:58 am

    #1894213

  • RE: Performance Tuning with SQL Server 2014 Standard

    mikes84 (8/6/2016)

    Regarding cost threshold, I've read many articles that suggest 50 is a good starting point. However, some of the queries and views I'm working with have a cost of...

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 7, 2016 at 5:57 am

    #1894212

  • RE: Performance Tuning with SQL Server 2014 Standard

    Increase your cost threshold. Far too low.

    Tune your code, tune your indexes. If the views are nested, fix that first.

    Consider some form of reporting server to offload the reports to.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 6, 2016 at 3:23 pm

    #1894204

  • RE: should we use json or xml in sqlserver.

    rajemessage 14195 (8/6/2016)

    should we change to jsaon and leave xml.

    No, you should in most cases go for a properly designed normalised data structure.

    Otherwise, whether you use json or xml depends...

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 6, 2016 at 3:19 pm

    #1894203

  • RE: will it make any diffrence if i change serialize to read commited.

    The answer to your question is 'maybe', because there's no where near enough information to answer any other way.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 6, 2016 at 3:16 pm

    #1894201

  • RE: how to put nolock with tabel alies

    Talking about interviews, I did one last week. The question that tipped the interview from 'maybe' to 'no' was when I asked about the cause of deadlocks and he replied...

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

    August 6, 2016 at 3:15 pm

    #1894200

Viewing 15 posts - 2,671 through 2,685 (of 49,552 total)