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What is auto update statistics asynchronously?
Auto Update Statistics Asynchronously If query optimizer finds out of date statistics, it updates the SQL Server Statistics first and then prepares the execution plan according to the recently updated statistics. If we enable the Auto Update Statistics Asynchronously, SQL Server does not wait to update the statistics.
Why do we need to update statistics in SQL Server?
Updating statistics ensures that queries compile with up-to-date statistics. However, updating statistics causes queries to recompile. We recommend not updating statistics too frequently because there is a performance tradeoff between improving query plans and the time it takes to recompile queries.
Is the auto update statistics async option disabled?
This option is set database by database and the default setting for this option is disabled. When this option is enabled, the Query Optimizer will not wait for the update of statistics, but will run the query first and update the outdated statistics afterwards.
When does auto update statistics become out of date?
When the automatic update statistics option, AUTO_UPDATE_STATISTICS, is on, the query optimizer determines when statistics might be out-of-date and then updates them when they are used by a query. Statistics become out-of-date after operations insert, update, delete, or merge change the data distribution in the table or indexed view.
How does auto update statistics work in APS?
For APS, the asynchronous statistics update option is ON by default, and the Query Optimizer updates statistics asynchronously. The AUTO_UPDATE_STATISTICS_ASYNC option applies to statistics objects created for indexes, single columns in query predicates, and statistics created with the CREATE STATISTICS statement.
When to auto update Statistics in SQL Server?
AUTO_UPDATE_STATISTICS. When the automatic update statistics option, AUTO_UPDATE_STATISTICS, is on, the query optimizer determines when statistics might be out-of-date and then updates them when they are used by a query.
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