Ms sql updating statistics

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The simplest scenario is if you want to rebuild all the indexes and update all the statistics.

As mentioned before, if you rebuild all your indexes then all the index statistics will also be updated by scanning all the rows on the table.

After having excellent response to my quiz – Why SELECT * throws an error but SELECT COUNT(*) does not? Note: Auto Update Statistics and Auto Create Statistics for database is TRUEExpected Result – Statistics should be updated – SQL SERVER – When are Statistics Updated – What triggers Statistics to Update However, the solution I am looking is where statistics should be updated automatically based on algorithm mentioned here. Vinod Kumar is not allowed to take participate over here as he is the one who has helped me to build this puzzle. Please leave a comment and if your comment consist valid answer, I will publish with due credit.

I have decided to ask another puzzling question to all of you. Here is the script to reproduce the scenario which I mentioned.

3) Rebuilding an index, for example by using the ALTER INDEX …

REBUILD statement, will update only index statistics with the equivalent of using WITH FULLSCAN.

This is true even if we encapsulate the select into a stored procedure.

1) By default, the UPDATE STATISTICS statement updates both index and column statistics.Along with 16 years of hands on experience he holds a Masters of Science degree and a number of database certifications.For any SQL Server Performance Tuning Issue send email at [email protected] INTO Exec Table (ID, First Name, Last Name, City) SELECT TOP 1000 ROW_NUMBER() OVER (ORDER BY a.name) Row ID, ‘Bob’,’smith’,’New York’ FROM sys.all_objects a CROSS JOIN sys.all_objects b GOSELECT First Name, Last Name, City FROM Exec Table WHERE city = ‘New York’sp_helpstats N’Exec Table’, ‘ALL’ DBCC SHOW_STATISTICS(Exec Table, ‘statistics’)GOINSERT INTO Exec Table (ID, First Name, Last Name, City) SELECT TOP 700 ROW_NUMBER() OVER (ORDER BY a.name) Row ID, ‘Bob’,’smith’,’New York’ FROM sys.all_objects a CROSS JOIN sys.all_objects b Go INSERT INTO Exec Table (ID, First Name, Last Name, City) SELECT TOP 850 ROW_NUMBER() OVER (ORDER BY a.name) Row ID, ‘Bob’,’smith’,’New York’ FROM sys.all_objects a CROSS JOIN sys.all_objects bsp_helpstats N’Exec Table’, ‘ALL’DBCC SHOW_STATISTICS(Exec Table, ‘statistics’)Update Statistics is Triggered when ever the optimizer is trying to build an optimal execution plan for the query , in the present scenario we are trying to query the same query twice SELECT First Name, Last Name, City FROM Exec Table WHERE City = ‘New York’and allowing the optimizer to reuse the existing plan ,which is considered as most optimal plan . Although the column statistics are invalidated by the time the second select statement is executed, the query is not compiled/recompiled but instead the existing query plan is reused.It is the “next” compiled query against the column statistics that will see that they are out of date and will then in turn instantiate the action of updating statistics.Some other more complicated scenarios include when you have jobs which rebuild your indexes based on their fragmentation level.

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