In Oracle, you can get an idea of the current state of the index by using the ANALYZE INDEX VALIDATE STRUCTURE command. If you don't have a maintenance window accommodate this task at least once a week, then you need to pay close attention to how your indexes are faring.ĭetermining if an Index Needs to Be Rebuilt If you wait much longer than a week, you risk hurting your SQL Server's performance due to the negative impact of wasted empty space and logical fragmentation. If you can't rebuild indexes on a nightly basis, then, it should be done once a week at a minimum. If your indexes fragment rapidly, and you have a nightly maintenance window that allows you to run the Rebuild Index task, in addition to all your other maintenance tasks, then, by all means, go ahead. With that in mind, here are a few guidelines regarding when to rebuild indexes: These decisions are highly dependent on the type of data you work with, as well as the indexes and queries that are utilized. It is not really feasible to devise a catch-all plan with regard to when and how often to rebuild indexes. In general, this means during a scheduled maintenance window. Both these considerations make it ideal as an offline activity, to be run when as few users as possible are accessing a database. How Often to Rebuild IndexesĪs mentioned in the introduction, rebuilding indexes is both a resource intensive and blocking task. In today's blog, we'll learn how often to build indexes and how to determine when an index needs to be rebuilt. Any queries trying to access this index in order to return the required results will be temporarily blocked, until the rebuild is complete. Worse, as an index is being rebuilt, locks will be placed on the index, preventing anyone from accessing it while the rebuilding occurs. Having said that, indexes should not be rebuilt to often, because it's a resource intensive task. Hence, rebuilding indexes every now and again can be quite beneficial. This causes their performance - and by extension - that of your database queries, to degrade. How to Tell when it's Time to Rebuild Indexes in Oracle by Robert GravelleĮvery so often, we need to rebuild indexes in Oracle, because indexes become fragmented over time.
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