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42
votes
3answers
50k views

Why is my database still fragmented after I rebuilt and reindexed everything?

I have a database which I tried to defragment all the tables at once by running this T-SQL: SELECT 'ALTER INDEX all ON ' + name + ' REORGANIZE;' + CHAR(10) + 'ALTER INDEX all ON ' + ...
38
votes
4answers
43k views

Hard and Fast rule for include columns in index

Is there any hard and fast rule to decide what columns and in which order it should be put in Included in non clustered index. I was just reading this post https://stackoverflow.com/questions/1307990/...
22
votes
3answers
12k views

Painless way to create a clustered index on a huge table?

So we have a customer site that is complaining about some seriously slow performance. I took one look and it's obvious that the problem is because Somebody Else (grrrr) designed a table holding some ...
21
votes
3answers
4k views

Is it OK to blindly add missing indexes?

I often use SSMS to test my slow stored procedures for missing indexes. Whenever I see a "Missing Index (Impact xxx)" my kneejerk reaction is to just create the new index. This results in a faster ...
19
votes
2answers
22k views

What are the differences between leaf and non-leaf pages?

I've been running some index usage reports, and I'm trying to get a definition of Leaf and Non-leaf. There seem to be both Leaf and Non-leaf Inserts, Updates, Deletes, Page Merges, and Page ...
17
votes
2answers
10k views

Central stored procedure to execute in calling database context

I am working on a customized maintenance solution using the sys.dm_db_index_physical_stats view. I currently have it being referenced from a stored procedure. Now when that stored procedure runs on ...
17
votes
1answer
10k views

When should you specify PAD_INDEX?

So, you can use FILLFACTOR to leave space in leaf index pages. Specifying PAD_INDEX also leaves space in intermediate nodes. What scenarios should you specify PAD_INDEX, and what benefit does it ...
11
votes
2answers
6k views

Finding the query causing the missing index DMVs

How can I find the query causing the missing index DMVs suggesting to create a particular index? Thank you.
11
votes
2answers
5k views

Is there a way to force an index to stay in memory with SQL Server 2008?

I've got a table with several millions rows, from which I need to run some queries from time to time. First query will usually be quite slow (around 10s), and subsequent queries are usually way faster ...
11
votes
1answer
1k views

How to set up indexed view when SELECTing TOP 1 with ORDER BY from different tables

I am struggling to setup an indexed view in the following scenario so that the following query performs without two clustered index scans. Whenever I create an index view for this query and then use ...
11
votes
2answers
4k views

How to prevent daily index fragmentation of 99%

I have a highscore table for 100.000 players that is being inserted into 2 times a day with one record per player. At the end of the day the index fragmentation for the indexes in that table is 99%. ...
10
votes
1answer
2k views

MSG 666 when running an insert query on 80M-row indexed table

Strangely, my stored procedure started to receive Msg 666 for some input data. Stored procedure fails on the last step when it tries to insert a row into a table with the following structure: ...
9
votes
3answers
3k views

Is there an advantage to not partition aligning an index?

I have the privilege of managing a large partitioned OLAP table. While reviewing this table I noticed one of the indexes is not aligned with the partitioning scheme. Since the author is not ...
9
votes
2answers
1k views

How much “Padding” do I put on my indexes?

How do you know how much "Padding" an index should have?
8
votes
4answers
24k views

When to add indexes to #temp tables?

When testing stored procedures in SSMS, it sometimes says there is a missing index on #someTempTable____________________000000000000005B] (someField) etc etc When I do add them like this to the sp: ...
8
votes
3answers
17k views

Tools for Identifying Needed Indexes

I want to create the best indexes for each table in my database. Is there a query or tool in SQL Server to help with this process?
8
votes
2answers
226 views

Non-Clustered Indexes - keys and nonkeys

I just want to make sure I'm on the right track with these concepts, so any feedback would be greatly appreciated. Here's my theory from the query I've just optimised, through a process of trial and ...
8
votes
3answers
5k views

Dropping Hypothetical Indexes

In the past I thought I'd deleted hypothetical indexes using either a DROP INDEX statement for clustered indexes and DROP STATISTICS statement for non-clustered indexes. I have a database that is ...
8
votes
3answers
1k views

How to create clustered index on 100 GB table

I have a heap table that takes about 104 GB of disk space with almost 3 billion rows. I am trying to create a clustered index on this table on the [WeekEndingDate] column. I have about 200 gb's free ...
7
votes
2answers
211 views

In SQL Server, is it possible to have a PRIMARY KEY on a table without either CLUSTERED or NONCLUSTERED indexes on the same key?

In Sql Server (2008), is it possible to have a PRIMARY KEY on a set of columns without either CLUSTERED or NONCLUSTERED indexes on the same set of columns? I am aware of the fact that PRIMARY KEY and ...
7
votes
1answer
1k views

How to set SQL Server index pages per fragment?

I have SQL Server 2008, and a number of databases. I have discovered that one of my table's indexes is extremely fragmented (How I know: http://msdn.microsoft.com/en-us/library/ms189858.aspx) The ...
7
votes
1answer
13k views

How do I alter index rebuild an entire database?

I want to reorganize the indexes of all tables in my SQL Server 2008 database, named 'db'. I try the following command: ALTER INDEX all ON db REBUILD And I get the following error: Cannot find the ...
7
votes
1answer
2k views

Two columns with and without index in where clause - How index works

I am executing a query on SQL Server 2008: SELECT col1 FROM table1 WHERE col2=val2 AND col3=val3 Here col2 has a non-clustered index, col1 is the PRIMARY KEY, and col3 does not have any index. Query ...
7
votes
2answers
7k views

Best value for fill factor in index

I use SQL Server 2008 R2 and want to set value for fill factor property in each index. I look for recipe to calculate best value for this property (have better performance when insert record) . Also ...
7
votes
1answer
19k views

Difference between Clustered Index and Unique Clustered Index? [closed]

I got difference between clustered index and unique index here. But what is the exact difference between clustered index and unique-clustered index? AFAIK creating clustered index can be done for a ...
7
votes
1answer
1k views

computed columns, index, clustered index and covering index?

We all know the we can only have one clustered view per table, cool. But apparently you don't have values of computed columns on leaf even when using a clustered index and they are computed each time. ...
6
votes
1answer
3k views

How much of a view is persisted when you create an index?

Say I have a view defined by the following SQL: SELECT t1.id, t2.name, t3.address FROM Table1 as t1 INNER JOIN Table2 t2 ON t1.id = t2.tID INNER JOIN Table3 t3 ON t1.id = t3.tID From what I ...
6
votes
2answers
3k views

Rebuilding index has impact on mdf/ldf files SQL Server 2008

While rebuilding index have used option 'SORT_IN_TEMPDB = ON' in order to avoid unnecessary growing your user database files. What does it exactly means? Is complete process done on TempDB and does ...
6
votes
1answer
2k views

Convert clustered primary key to non-clustered and use another column for the clustered index

I have a large table with a primary key (GUID) that is also the clustered index. There is already a integer sequence based field. So I want to leave the GUID as the PK and make the integer column the ...
6
votes
4answers
447 views

SELECT * WHERE VarCharColumn IN (…) Optimization

I have a list of 3000 strings, and I am passing them (twenty at a time) into a parametrized IN clause. It definitely isn't getting the results I would like to see ~ 500ms per execution. The column is ...
6
votes
1answer
218 views

Composite or Single-Field Clustering Key

My DBA and I are having a disagreement on index structure. Consider data for a medical claim... We have the Header table with fields like: ClaimId (varchar(50)), PaidAmount, MemberID... and for ...
6
votes
1answer
2k views

Are there any performance benefits to using a hash table with no clustered index?

I have this table: CREATE TABLE [dbo].[relatea] ( [mid] [varchar](16) NOT NULL, [sid] [varchar](16) NOT NULL ) It stores hash matches. Is there any benefit to having this as a heap? It has ...
6
votes
1answer
2k views

SQL Server: Effect of Setting These Index Options

A reindexing script was recently run in our dev environment that set ALLOW_ROW_LOCK = FALSE and ALLOW_PAGE_LOCKS = FALSE on all the indexes in the database. This was done while testing new reindexing ...
6
votes
2answers
7k views

Dropping and recreating indexes for performance reasons?

I'm maintaining Somebody Else's Code. There's a stored procedure that's run once a day or week (depending on config), that migrates a bunch of records from an active table to an archive. But it's ...
6
votes
3answers
4k views

Does having an index on a VARCHAR column with a lot of very similar starting values have bad performance

We seem to be having quite unusual bad performance on queries that use an index. for example the table looks like PK BIGINT ID VARCHAR(50) Col1 Col2 etc So we need to insert a row in the ...
6
votes
1answer
510 views

Can filtered indexes help improve queries that are based on a time entered or should this be avoided?

I'm just learning about the new filtered indexes in MS SQL 2008 and I'm trying to understand where they would hurt and where they would help. I can see that adding a filtered index to an employees ...
6
votes
1answer
418 views

Landed as BI, but databases are a big WTF, what to do?

Maybe a duplicate, but I believe my case is a bit different. From one of the answers I got to this post on SQL Server Central that also comes handy too but is not quite the same scenario: 9 Things to ...
6
votes
2answers
6k views

Bitmask Flags with Lookup Tables Clarification

I've received a dataset from an outside source which contains several bitmask fields as varchars. They come in length as low as 3 and as long as 21 values long. I need to be able to run SELECT queries ...
6
votes
1answer
3k views

Schema design: Use of association (aka: bridge/junction) table vs foreign key constraint with composite index containing a non-key field

This is an inventory database for IT assets. The models used are trimmed in order to focus on the problem at hand. Using SQL Server 2008. Thanks for taking the time to read and for any input you can ...
5
votes
1answer
969 views

Which fillfactor is used by ALTER INDEX REBUILD?

From technet I got the impression, that I either have to explicitly set the wanted fillfactor or when I do not specify it, the default fillfactor 0 is choosen. For tables I know to get rows added ...
5
votes
2answers
882 views

If I update a column record in a table, will indexes that do NOT have this column in it be affected?

In terms of performance if I have a table like so: CREATE TABLE [TESTDATA].[TableA]( [Col1] [nchar](5) NOT NULL, [Col2] [nchar](2) NULL, [Col3] [float] NULL CONSTRAINT [TableA_PK] PRIMARY ...
5
votes
2answers
208 views

Are existing entries immediately included into a newly created index?

Suppose I have a table Stuff with a column City and no indices including that column. I populate the table. Then I decide to create an index: CREATE INDEX [StuffOnCityIndex] ON [dbo].[Stuff](City ASC)...
5
votes
1answer
3k views

What is a non-clustered index scan

I know what table scan, clustered index scan and index seek is but my google skills let me down to find a precise explanation into non clustered index scans. Why and when a query uses a non clustered ...
5
votes
1answer
3k views

creating an index for varchar column greater than 900 bytes

I have a var char column in SQL Server 2008 which is usually less than 100 bytes but in some cases can be huge up 5607 bytes. I need to index it, and I can't because the max index size in SQLServer is ...
5
votes
2answers
2k views

Should I use a composite or single-column index?

I have the following columns in my database table (Medicines). ID bigint, MedicineName nvarchar(50), BrandName nvarchar(50), MedicineCode nvarchar(20), and price,quantity. I am making a stored ...
5
votes
1answer
588 views

RESOURCE_SEMAPHORE_QUERY_COMPILER waits in Microsoft SQL Server 2008 Enterprise

Could fragmented indexes on Microsoft SQL Server 2008 Enterprise cause RESOURCE_SEMAPHORE_QUERY_COMPILER waits? The last two weeks one of our applications has had downtime due to ...
5
votes
1answer
67 views

SQL Server 2008 Index

What would be the best index(es) to add to the tables in order to make this query as fast as possible. The sd.incidents tables is about 2.5M records, problems about 8K, and changes about 120K. select ...
4
votes
1answer
3k views

How are bit fields sorted for an index?

I am building a compound index, and I'm not 100% sure which way to include a bit field that is part of the table. The index will be for something similar to a list of forum topics, where I want the ...
4
votes
1answer
7k views

Ola Hallengren Index Optimise Script not Rebuilding Indexes [closed]

I have downloaded Ola Hallengren's script and deployed to master database. I run it using the below... EXECUTE dbo.IndexOptimize @Databases = 'USER_DATABASES', @FragmentationLow = NULL, @...
4
votes
2answers
11k views

Find fulltext indexes in SQL Server 2008

How do I find a list of tables that have a FULLTEXT INDEX applied to them on a given database? For example, you can enable and disable a FULLTEXT INDEX like this: ALTER FULLTEXT INDEX ON [dbo].[...