Recent Posts

  • TSQL Tuesday #88 -Communication is the Key

    TSQL Tuesday #88 -Communication is the Key

    I thank Kennie Nybo Pontoppidan (b|t) for hosting TSQL Tuesday #88. Topic for this month is daily database related WT…….

    TSQL2SDAY-300x300

    Last week I was setting up a collection of wait statistics with five minutes interval using a while loop. I was wrapping up Paul Randal’s (b|t) code from this blog post in a loop and persisting in a table to analyze later.

    I made it a habit in my career to have my peers review my code. I sent my code to one my colleague and asked him to review. Meantime …


  • View Multiple System Health Extended Event Files

    Last week I blogged about increasing retention of System Health session files. In this post I will show how you can open multiple files at once and work with the data as one set.

    If you select multiple System Health extended event files (with extension .xel) and click open each file will open in separate window of SQL Server Management Studio (SSMS).

     

    XEFiles1

    You can see here 4 files opened in 4 different windows. Now you cannot sort, group, apply filter, export data from all 4 windows as one data set.

    XEFiles2

     

    For opening all these files in one window …


  • SQL Server system_health Session Retention

    As per Microsoft’s books online

    The system_health session is an Extended Events session that is included by default with SQL Server. This session starts automatically when the SQL Server Database Engine starts, and runs without any noticeable performance effects. The session collects system data that you can use to help troubleshoot performance issues in the Database Engine. Therefore, we recommend that you do not stop or delete the session.

    What this article does not tell you is your individual file size is 5 MB and number of maximum rollover file is 4. Meaning you will only get 20 MB of …


  • SQL Server Fullscan Statistics Being Overwritten with Sample Statistics

    SQL Server Fullscan Statistics Being Overwritten with Sample Statistics

    I observed this behavior only in following version of SQL Server while using Always On Availability Group feature.

    Version: Microsoft SQL Server 2012 (SP3) (KB3072779) – 11.0.6020.0 (X64) Oct 20 2015 15:36:27 Copyright (c) Microsoft Corporation Enterprise Edition: Core-based Licensing (64-bit) on Windows NT 6.3 (Build 9600: )

    In this article by David Barbarin similar behavior was also observed in SQL Server 2014 SP2.

    Once I update my statistics with fullscan, with in 10~20 seconds some of the statistics on the same table are getting update on secondary with a sample pecent of rows. Meaning my best statistics are being …