Even though you can create 2 indexes on the same column, there's no point of doing that. Normally the only thing that happens is that you use extra space.
There are few special situations when having more than one index would be beneficial, but these are rare cases.
As Mehdi already pointed out you should rebuild the indexes regularly. It could be once a month or once a year depending how often you have changes in your data.
Another thing is your statistics. The problem that queries become slower could be caused by the fact that the statistics are out-of-date. Updating statistics is something you should do for example every week, meaning a lot more often than rebuilding indexes.
To ensure that you have good statistics:
- check from your database options that Auto Create Statistics and Auto Update Statistics are both true
- update your statistics on every table using UPDATE STATISTICS[^]
- OR create for example a maintenance plan where you update the statistics on regular intervals
Submit an article or tip