allows the SQL Server query optimizer to produce good query plans consistently, while keeping development and administration costs low 2.
When that operation happens, statistics are automatically updated (provided that isn't turned off for the index).
Exactly how often you should be updating statistics depends greatly on how much data modification your indexes and data is receiving.
SAP Sybase Adaptive Server Enterprise (ASE) uses a cost-based optimizer which balances the cost of finding the best query execution plan with the costs of running the query in different ways.
To do this, it checks a histogram that identifies the data distribution, and uses this information to determine join orders, index selection, and more.
My Question Is: When should we be Updating the Statistics, and why?
This seems like the kind of thing we should do less frequently than every day.Some have claimed the update statistics command causes blocking and contention.In earlier versions of ASE, this may have sometime happened; however, in the newer releases of ASE, locking is minimal and this should not be a significant concern.If there is very little modification () to the data, then you could have a more infrequent schedule for the update statistics job.One way to find out if your statistics are stale is to look at the execution plans and if you estimated rows greatly differ from your actual rows returned then that is a good indication that the interval needs to be upped.The statistics auto update is triggered by query optimization or by execution of a compiled plan, and it involves only a subset of the columns referred to in the query.