SQL Galaxy (9/23/2016)
could Pls. explain the following outputs
index_advantage = 7983.73805718724
user_seeks = 116
avg_total_user_cost = 92.4947293095018
avg_user_impact = 74.41
index_advantage = This is a calculated column. Indexes with a higher index_advantage are those that SQL Server considers will have the biggest positive impact on reducing workload, based on reducing query cost and the projected number of times they will use the index.
user_seeks = Number of seeks caused by user queries that the recommended index in the group could have been used for.
avg_total_user_cost = Average cost of the user queries that could be reduced by the index in the group.
avg_user_impact = Average percentage benefit that user queries could experience if this missing index group was implemented. The value means that the query cost would on average drop by this percentage if this missing index group was implemented.
Bear in mind that if you make a change to an index for a given table, then all the missing index statistics for that table are cleared out and repopulated again over time. If you run this query shortly after an index change, it will probably—and inaccurately—inform you that there are no missing indexes for this table.
You should never just blindly add every index that this query suggests, especially if you have an online transaction processing (OLTP) workload. Instead, you need to examine the results of the query carefully and manually filter out results that are not part of your regular workload.