The process of determining which indexes are useful and which are not.

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7
votes
4answers
1k views

How will large index INCLUDE fields effect system performance?

This question is about SQL Server index performance with a varchar(2000) as an INCLUDE in a covering index. I’m trying to improve performance in an slow and unstable database application. In some ...
12
votes
1answer
4k views

Should I use many single field indexes, instead of specific multi column indexes?

This question is about the effectiveness of a SQL Server indexing technique. I think it is known as "index intersection". I'm working with an existing SQL Server (2008) application that has a number ...
6
votes
2answers
4k views

What is the difference between ALTER INDEX and DBCC DBREINDEX?

Is the only difference between ALTER INDEX [index_name] on [object_name] REBUILD with (ONLINE=OFF, FILLFACTOR=90) and DBCC DBREINDEX([dbname], 90) just that the DBCC command will reindex all ...
3
votes
1answer
186 views

Filtered index statistics refresh threshold

We have filtered indexes in our production environment. While doing some research about them, I came across this article "Filtered indexes and filtered stats might become seriously out-of-date" ...
2
votes
1answer
358 views

Is staggering reindexing jobs a good strategy?

I have inherited a server with 35 databases and a job that reindexes all tables on all databases (using sp_MSForEachTable). It's taking over 14 hours to complete and is now blocking other processes. ...
3
votes
1answer
2k views

Oracle not using index when > used in where clause

We have a relatively classic scenario where the date clause of the query generated by the application uses a "greater than" for a given date. Because there is no end clause to the date range, oracle ...
2
votes
1answer
310 views

In DB2, what are the alternative ways of evaluating an index's (or several indexes) benefit?

I'm trying to evaluate different approaches to analyzing the benefit of changing the set of indexes that are available. If I pick some representative queries from my workload, I can run EXPLAIN and ...
2
votes
2answers
980 views

How can an identity primary key index become fragmented?

From what I understand about index fragmentation, this should not be possible. The cases I have found in my databases are non-clustered. Example: ALTER TABLE [dbo].[ClaimLineInstitutional] ADD ...
8
votes
4answers
395 views

What are the performance considerations between using a broad PK vs a separate synthetic key and UQ?

I have several tables where records can be uniquely identified with several broad business fields. In the past, I've used these fields as a PK, with these benefits in mind: Simplicity; there are no ...
5
votes
1answer
556 views

SQL Server 2008 Maintenance Plan Failure

Instead of using my old school index rebuild script I had decided to use 2008's built-in Maintenance Plan to do a simple Rebuild Index task. The details are: Connection = Local server connection ...
0
votes
1answer
2k views

Reindexing Partitioned Table Indexes

Historic Reporting Server running SQL 2008 R2. I'm trying to tweak the fill factor. I have a job that records the fragmentation when the jobs runs in the early hours. For every table that had high ...
11
votes
2answers
5k views

How to know when/if I have too many indexes?

Running Microsoft SQL Server Profiler every now and then, it suggests me with a bunch of new indexes and statistics to create ("...97% estimated improvement..."). From my understanding every added ...
4
votes
3answers
354 views

Using DTA vs. evaluating DMVs?

Currently I am confronted with a production SQL Server database where someone had added almost all missing index proposals from DTA. Form How to determine if an Index is required or necessary I have ...