SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED; GO DBCC TRACEON (8666); GO WITH XMLNAMESPACES (' as p) SELECT AS SQLCommand, qp.query_plan, Stats Used.
XMLCol.value('@Field Value','NVar Char(500)') AS Stats Name FROM sys.dm_exec_cached_plans cp CROSS APPLY sys.dm_exec_query_plan(cp.plan_handle) qp CROSS APPLY sys.dm_exec_sql_text (cp.plan_handle) qt CROSS APPLY query_plan.nodes('//p: Field[@Field Name="wsz Stat Name"]') Stats Used(XMLCol) WHERE LIKE '%UPDATE%' AND LIKE '%Product ID%'; GO DBCC TRACEOFF(8666); GO statistic object in the query plan, and because it was out of date, SQL Server automatically updated it.
So we have to manually update stats and see some improvement.
I am sure scheduling FULL SCAN would be a challenge. Please suggest how I can make use of updating stats in a much better way for such a large DB and how to play with that sample rate?
During the session I went through a demo that showed the automatic update of a statistic.Summary As I stated initially, I wanted to write this post to clear up any confusion surrounding automatic updates for statistics.Even if a statistic becomes outdated as the result of a modification, it will not automatically update after the modification completes.The database had the Auto Update Statistics option enabled, and I had added almost 25,000 rows to a table with 121,000 rows.The number of rows added via the bulk import was just over the limit to trigger an auto-update of statistics for the next query, which I showed.Now let’s issue an update against statistic object automatically updated.We could simply assume that the optimizer used this object in the plan.The statistic will automatically update the next time a query plan uses it.I am looking here for experts' advice on how to manage updating stats for very large database approx 18 TB.To be clear, if a query plan exists in cache and that plan uses specific statistics, when the query executes SQL Server checks to see if any of the statistics used in the plan are out of date.If they are, then the automatic update of those statistics occurs.