How Dose It Matter For The Non-clustered Index Key Columns And Included Columns?
Apr 24, 2007
Hi, all experts here,
Thanks a lot for your kind attention.
As I am creating the non-clustered indexes for the tables, I dont quite understand how dose it really matter to put the columns in the index key columns or put them into the included columns of the index?
I am really confused about that and I am looking forward to hearing from you and thank you very much again for your advices and help.
With best regards,
Yours sincerely,
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May 8, 2014
I am trying to tune a process that is running slowly. I analyzed the process using the Database Engine Tuning Advisor, and it recommended the creation of 3 indexes, all non-clustered:
1) ColA, include ColB
2) ColA, include ColC
3) ColA, include ColD
So... I created a single non-clustered index on:
4) ColA, include ColB, ColC, ColD
That should do the same thing, right? A look at my execution plan shows that the index I created is being scanned -- 3 times. What is puzzling me, though, is that the Database Engine Tuning Advisor is still recommending I create these 3 separate indexes, even with the index (4) that I created in existence.
If it matters, ColA, ColB, ColC and ColD are all int FKs.
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Nov 14, 2011
I would like to know the impacts (if any) of adding nonclustered index with included columns on large tables (these tables are populated by bulk insert from text files).
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Oct 4, 2007
I'm using sys.dm_db_missing_index_details to find missing indexes on a database that is currently in testing. After running a bunch of our reports, there are several suggested indexes on 3 or 4 columns that have 15 - 20 included columns. The included columns are mostly varchars ranging from 1 to 150 characters along with a couple of date columns. My index size on that table is already nearly twice the size of the data.
I don't think it's a good idea to add an index with that many columns, but the information I've read on included columns is very general. I'm wondering if there is something about them that I don't understand that would make this a good idea.
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Nov 1, 2007
I have a table<table1> with 804668 records primary on table1(col1,col2,col3,col4)
Have created non-clustered index on <table1>(col2,col3,col4),to solve a performance issue.(which is a join involving another table with 1.2 million records).Seems to be working great.
I want to know whether this will slow down,insert and update on the <table1>?
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Mar 28, 2014
I have a table with clustered index on that. I have only 5 columns in that table. Execution plan is showing that Index scan occurred. What are the cause of the Index scan how can we change that to index seek?
I am giving that kind of similar query below
SELECT @ProductID= ProductID FROM Product WITH (NOLOCK) WHERE SalesID= '@salesId' and Product = 'Clothes '
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Oct 8, 2014
The Delete-Insert update happens for key columns of Indexes and that makes sense.
But I am confused that why Delete-Insert update happens for Included columns of nonclustered indexes, where I expected them to be InPlace updates ???
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Dec 13, 2007
Hello:
I am running into an issue with RS2k PDF export.
Case: Exporting Report to PDF/Printing/TIFF
Report: Contains 1 table with 19 Columns. 1 column is static, the other 18 are visible at the users descretion. Report when printed/exported to pdf spans 2 pages naturally, 16 on the first page, 3 on the second, and the column widths have been adjusted to provide a perfect page span .
User A elects to hide two of the columns, and show the rest. The report complies and the viewable version is perfect, the excel export is perfect.. the PDF export on the first page causes every fith column, starting with the last column that was hidden to be expanded to take up additional width. On the spanned page, it renders the first column on that page correctly, then there is a white space gap equal to the width of the hidden columns and then the rest of the cells show with the last column expanded to take up the same width that the original 2 columns were going to take up, plus its width.
We have tried several different settings to see if it helps this issue or makes it worse. So far cangrow/canshrink/keep together have made no impact. It is not possible to increase the page size due to limited page size selection availablility for the client. There are far too many combinations of what the user can elect to show or hide to put together different tables to show and hide on the same report to remove this effect.
Any help or suggestion on this issue would be appreciated
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Nov 14, 2006
the query:
SELECT a.AssetGuid, a.Name, a.LocationGuid
FROM Asset a WHERE a.AssociationGuid IN (
SELECT ada.DataAssociationGuid FROM AssociationDataAssociation ada
WHERE ada.AssociationGuid = '568B40AD-5133-4237-9F3C-F8EA9D472662')
takes 30-60 seconds to run on my machine, due to a clustered index scan on our an index on asset [about half a million rows]. For this particular association less than 50 rows are returned.
expanding the inner select into a list of guids the query runs instantly:
SELECT a.AssetGuid, a.Name, a.LocationGuid
FROM Asset a WHERE a.AssociationGuid IN (
'0F9C1654-9FAC-45FC-9997-5EBDAD21A4B4',
'52C616C0-C4C5-45F4-B691-7FA83462CA34',
'C95A6669-D6D1-460A-BC2F-C0F6756A234D')
It runs instantly because of doing a clustered index seek [on the same index as the previous query] instead of a scan. The index in question IX_Asset_AssociationGuid is a nonclustered index on Asset.AssociationGuid.
The tables involved:
Asset, represents an asset. Primary key is AssetGuid, there is an index/FK on Asset.AssociationGuid. The asset table has 28 columns or so...
Association, kind of like a place, associations exist in a tree where one association can contain any number of child associations. Each association has a ParentAssociationGuid pointing to its parent. Only leaf associations contain assets.
AssociationDataAssociation, a table consisting of two columns, AssociationGuid, DataAssociationGuid. This is a table used to quickly find leaf associations [DataAssociationGuid] beneath a particular association [AssociationGuid]. In the above case the inner select () returns 3 rows.
I'd include .sqlplan files or screenshots, but I don't see a way to attach them.
I understand I can specify to use the index manually [and this also runs instantly], but for such a simple query it is peculiar it is necesscary. This is the query with the index specified manually:
SELECT a.AssetGuid, a.Name, a.LocationGuid
FROM Asset a WITH (INDEX (IX_Asset_AssociationGuid)) WHERE
a.AssociationGuid IN (
SELECT ada.DataAssociationGuid FROM AssociationDataAssociation ada
WHERE ada.AssociationGuid = '568B40AD-5133-4237-9F3C-F8EA9D472662')
To repeat/clarify my question, why might this not be doing a clustered index seek with the first query?
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Jun 13, 2000
Does anyone have a recommendation for creating an index on a datetime column?
We use alot of dateranges in our statements and none of them perform very well.
Thanks
Pete Karhatsu
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May 5, 2015
Getting old favourite message 'Out of Memory' when running a horizontal clustered chart with Category: 200 items Series: 200 items per Category.URL... 'By default, the report server sets WorkingSetMaximum to the amount of available memory on the computer. This value is detected when the service starts.'Â
The report has been tried on 3 large servers with 30GB & 60GB memory. The report runs on a 2008 install but not a 2008R2 install. We've created a test report that simply generates a series of data 1-n for Category and 1-n for Series where n can be set by parameter - so the issue is not to do with the volume of data or the processing required by SSMS. The report runs if the data is output to a table rather than a chart - so the issue appears to be with rendering the chart.
The chart is rendered when the Category has 200 items with a Series of 150 per Category. The report fails with Category 200 items and Series 200 per Category.
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Apr 18, 2005
How do you index through a set of Columns Programmatically using SQL. I have a Table all the columns have the same data for different dates. Column names are Col_0, Col_1, Col_2,.....Col_100, Col_101. I need to perform the same calculation on each column to manipulate the data into a different table. Is it possible to do a While loop that changes the Column name in a SELECT statement. I have tried to do this but can't seem to get it to work. Please help !
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May 8, 2005
I am trying to index through the columns of MyTable so I can do the same work on all columns. I know how to get the column names from MyTable but when I use @MyColName in the SELECT statement to get MyTable Column 0 Row values I get a table with the column name in each row cell. I can't get the syntax correct to return the value in each cell for that column.
This is a extremely simplified example !!!!!!DECLARE @MyColName nvarchar(30)
--Get the MyTable Column 0 NameSELECT @MyColName = Col_Name(Object_ID('MyTable'), 0)
--Display the MyTable Column 0 Row valuesSELECT @MyColName FROM MyTable --This is the syntax I can not get correct
Can anyone help ?
Thanks
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Apr 19, 2013
I find to be able to have multiple NULL entries in the following constraint:
Code:
CREATE UNIQUE INDEX my_uidx ON my_table(my_col1,my_col2) WHERE ??? IS NOT NULL;
But is not possible to check multiple columns in "WHERE".
I using SQL Server 2012 Express
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Jun 19, 2013
I want to make an index with the following columns, actually together they constitute the PK of the table so the index is created automatically.
The question is witch sort order is the best to have if I want to fetch all rows for one date and one resource? And why?
WHERE Resource = "Car 1" AND Date = "2013-03-03"
Resource, Date, Time
Or
Date, Time, Resource
Below is an example with tree resources, but in reality there can be a lot more and also years of dates.
Car 1, 2013-03-03, 10.00
Car 1, 2013-03-03, 11.00
Car 1, 2013-03-03, 12.00
Car 1, 2013-03-04, 10.00
[Code] ......
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May 20, 2008
Is there a dynamic management view or system procedure which I can use to find out what columns are in an index, what columns are as an INCLUDE in the index and whether or not the column(s) are ascending or descending. This is excluding the utilities I already know about below:
sys.indexes
sys.index_columns
sp_helpindex
dm_db_index_physical_stats
dm_db_index_operational_stats
I only ask because it is a pain to look through the sys.indexes and sys.index_columns tables every time I want to know about what columns are in the index created. I also know that scripting the index would give me the information I need but there must be a better way.
Many Thanks
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Feb 23, 2006
my table :
CREATE TABLE [dbo].[users] (
[ID] [int] NOT NULL ,
[A1] [nvarchar] (100) NULL ,
[A2] [nvarchar] (100) NULL ,
[A3] [nvarchar] (100) NULL
) ON [PRIMARY]
i must keep ID columns as primary key
ALTER TABLE [dbo].[users] WITH NOCHECK ADD
CONSTRAINT [PK_users] PRIMARY KEY CLUSTERED
(
[ID]
) ON [PRIMARY]
but now A1+A2 must be unique
how can i do it ?
thank you
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Mar 31, 2014
When creating a column store index, are there any reasons not to include all columns, besides index size of course? i.e. will the index be more versatile with more columns or should I treat it exactly like its a standard index, putting only necessary columns, in the correct order?
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Dec 22, 2005
Table DDL below:The tables I have contain Timesheet information. Each row in thetblTSCollected table contains an entry for an employee into thetimesheet system, specifically by scanning the barcode on their badge.A whole bunch of business logic periodically attempts to "pair" theseinto logically matched scans. For example, some employees will scan inand out of a single place of work. For these there will be a rowwritten to the tblTSRuleApplied table which contains, inter alia andsome redundant data, the fldCollectedID for the two rows. The earlierwill be put into the fldStartTimeCollectedID, and the later into thefldEndTimeCollectedID. Some employees will clock on at their base,then perform sub-duties at different locations during the day, andclock off at their home base at the end of their shift. For these, thesystem would identify the outer records as a matching pair, and thenpair up inner records by location.However, if the employee fails to enter a valid "clocking in and out"pair (for example, if they clock in at the wrong location) the systemneeds to generate a "dummy" "clocking in and out" record for thepayroll department. Ideally, this would have NULL values in thefldStartTimeCollectedID and fldEndTimeCollectedID columns. This wouldalert a user in a different part of the system, where missingtimesheets were being arbitrated, that an employee appeared to havefailed to clock in for that day. Of course, the user could seeon-screen that they had clocked in, but at an incorrect location.Unfortunately, the database designer is not here for the moment (he wasknocked off his bicycle recently), but he put a unique index on thetblTSRuleApplied table that prevents the same value being entered intothe fldStartTimeCollectedID and fldEndTimeCollectedID columns. This isgenerally A Good Thing, since we don't want the same timesheet scan toform both a "clocking on" event and a "clocking off" event.So, is there any way of retaining the requirement that thefldStartTimeCollectedID and the fldEndTimeCollectedID columns may notcontain the same value in a single row, UNLESS that value is NULL inwhich case all is hunky dory. I should add that the clients don't muchcare for Triggers (and neither do I for that matter).Many thanks if you are able to help.Edwardif exists (select * from dbo.sysobjects where id =object_id(N'[dbo].[FK_tblTSRuleApplied_tblTSCollected]') andOBJECTPROPERTY(id, N'IsForeignKey') = 1)ALTER TABLE [dbo].[tblTSRuleApplied] DROP CONSTRAINTFK_tblTSRuleApplied_tblTSCollectedGOif exists (select * from dbo.sysobjects where id =object_id(N'[dbo].[FK_tblTSRuleApplied_tblTSCollected1]') andOBJECTPROPERTY(id, N'IsForeignKey') = 1)ALTER TABLE [dbo].[tblTSRuleApplied] DROP CONSTRAINTFK_tblTSRuleApplied_tblTSCollected1GOif exists (select * from dbo.sysobjects where id =object_id(N'[dbo].[FK_tblTSArbAccept_tblTSRuleApplied]') andOBJECTPROPERTY(id, N'IsForeignKey') = 1)ALTER TABLE [dbo].[tblTSArbAccept] DROP CONSTRAINTFK_tblTSArbAccept_tblTSRuleAppliedGOif exists (select * from dbo.sysobjects where id =object_id(N'[dbo].[FK_tblTSCollected_tblTSRuleApplied]') andOBJECTPROPERTY(id, N'IsForeignKey') = 1)ALTER TABLE [dbo].[tblTSCollected] DROP CONSTRAINTFK_tblTSCollected_tblTSRuleAppliedGOif exists (select * from dbo.sysobjects where id =object_id(N'[dbo].[tblTSCollected]') and OBJECTPROPERTY(id,N'IsUserTable') = 1)drop table [dbo].[tblTSCollected]GOif exists (select * from dbo.sysobjects where id =object_id(N'[dbo].[tblTSRuleApplied]') and OBJECTPROPERTY(id,N'IsUserTable') = 1)drop table [dbo].[tblTSRuleApplied]GOCREATE TABLE [dbo].[tblTSCollected] ([fldCollectedID] [int] IDENTITY (1, 1) NOT NULL ,[fldEmployeeID] [int] NULL ,[fldLocationCode] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_ASNULL ,[fldTimeStamp] [datetime] NULL ,[fldRuleAppliedID] [int] NULL ,[fldBarCode] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,[fldProcessed] [smallint] NOT NULL) ON [PRIMARY]GOCREATE TABLE [dbo].[tblTSRuleApplied] ([fldEmpRuleID] [int] NOT NULL ,[fldRuleAppliedID] [int] IDENTITY (1, 1) NOT NULL ,[fldStartTime] [datetime] NULL ,[fldEndTime] [datetime] NULL ,[fldStartTimeCollectedID] [int] NULL ,[fldEndTimeCollectedID] [int] NULL ,[fldStartArbStatus] [smallint] NULL ,[fldEndArbStatus] [smallint] NULL ,[fldDurationArbStatus] [smallint] NULL ,[fldPrimary] [smallint] NOT NULL ,[fldDateEntered] [datetime] NULL ,[fldEnteredBy] [int] NULL) ON [PRIMARY]GOALTER TABLE [dbo].[tblTSCollected] WITH NOCHECK ADDCONSTRAINT [DF_tblTSCollected_fldProcessed] DEFAULT (0) FOR[fldProcessed],CONSTRAINT [PK_tblTimesheetCollected] PRIMARY KEY CLUSTERED([fldCollectedID]) WITH FILLFACTOR = 90 ON [PRIMARY]GOALTER TABLE [dbo].[tblTSRuleApplied] WITH NOCHECK ADDCONSTRAINT [DF_tblTSRuleApplied_fldPrimary] DEFAULT (1) FOR[fldPrimary],CONSTRAINT [PK_tblTSRuleApplied] PRIMARY KEY CLUSTERED([fldRuleAppliedID]) WITH FILLFACTOR = 90 ON [PRIMARY] ,CONSTRAINT [IX_tblTSRuleApplied_1] UNIQUE NONCLUSTERED([fldStartTimeCollectedID],[fldEndTimeCollectedID]) WITH FILLFACTOR = 90 ON [PRIMARY]GOALTER TABLE [dbo].[tblTSCollected] ADDCONSTRAINT [FK_tblTSCollected_tblEmployee1] FOREIGN KEY([fldEmployeeID]) REFERENCES [dbo].[tblEmployee] ([fldEmployeeID]),CONSTRAINT [FK_tblTSCollected_tblLocation] FOREIGN KEY([fldLocationCode]) REFERENCES [dbo].[tblLocation] ([fldLocationCode]),CONSTRAINT [FK_tblTSCollected_tblTSRuleApplied] FOREIGN KEY([fldRuleAppliedID]) REFERENCES [dbo].[tblTSRuleApplied] ([fldRuleAppliedID])GOALTER TABLE [dbo].[tblTSRuleApplied] ADDCONSTRAINT [FK_tblTSRuleApplied_tblTSCollected] FOREIGN KEY([fldStartTimeCollectedID]) REFERENCES [dbo].[tblTSCollected] ([fldCollectedID]),CONSTRAINT [FK_tblTSRuleApplied_tblTSCollected1] FOREIGN KEY([fldEndTimeCollectedID]) REFERENCES [dbo].[tblTSCollected] ([fldCollectedID]),CONSTRAINT [FK_tblTSRuleApplied_tblTSDurationStatus] FOREIGN KEY([fldDurationArbStatus]) REFERENCES [dbo].[tblTSDurationStatus] ([fldStatus]),CONSTRAINT [FK_tblTSRuleApplied_tblTSEmpRules] FOREIGN KEY([fldEmpRuleID]) REFERENCES [dbo].[tblTSEmpRules] ([fldEmpRuleID]),CONSTRAINT [FK_tblTSRuleApplied_tblTSTimeStatus] FOREIGN KEY([fldStartArbStatus]) REFERENCES [dbo].[tblTSTimeStatus] ([fldStatus]),CONSTRAINT [FK_tblTSRuleApplied_tblTSTimeStatus1] FOREIGN KEY([fldEndArbStatus]) REFERENCES [dbo].[tblTSTimeStatus] ([fldStatus])GO
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Jul 20, 2005
Hi,I would like to add a unique index that consists of two fields in atable.e.g. tbl_A (field1,field2) -- field1 & field2 Indexed and combinationmust be Unique.Can anyone tell me the actual sql syntax to create this index?Thanks,June.
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May 29, 2007
I have 2 columns in a table namely ColA and ColB.all DML operations are through views n every view has
Where clause i.e where ColA=€?€? with check option .
All most all my DML queries are using where clause on ColB
Where ColB=€?€?
Now my question is I have a clusted index on both ColA and ColB.in which order I have to create cluster index .
i.e ColA ASC,ColB ASC or ColB ASC,ColA ASC.
Is there any performance gain we can achieve with their order
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Jun 20, 2007
I am upgrading from Access, where you can only have 10 fields in a primary key or unique index. Is this also the limit in SQL Server? If not, what is the limit?
Thanks for any help on this.
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Sep 4, 2015
We are going to use SQL Sever change tracking. The problem is that some of our tables, which are to be tracked, have no primary keys. There are only unique clustered indexes. The question is what is the best way to turn on change tracking for these tables in our circumstances.
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Aug 28, 2015
I desire to have a clustered index on a column other than the Primary Key. I have a few junction tables that I may want to alter, create table, or ...
I have practiced with an example table that is not really a junction table. It is just a table I decided to use for practice. When I execute the script, it seems to do everything I expect. For instance, there are not any constraints but there are indexes. The PK is the correct column.
CREATE TABLE [dbo].[tblNotificationMgr](
[NotificationMgrKey] [int] IDENTITY(1,1) NOT NULL,
[ContactKey] [int] NOT NULL,
[EventTypeEnum] [tinyint] NOT NULL,
[code]....
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Jul 19, 2013
I have created two tables. table one has the following fields,
                     Id -> unique clustered index.
        table two has the following fields,
                     Tid -> unique clustered index
                     Id -> foreign key of table one(id).
Now I have created primary key for the table one column 'id'. It's created as "nonclustered, unique, primary key located on PRIMARY". Primary key create clustered index default. since unique clustered index existed in table one, it has created "Nonclustered primary key".
My Question is, What is the difference between "clustered, unique, primary key" and "nonclustered, unique, primary key"? Is there any performance impact between these?
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Jan 4, 2008
I have large table with 10million records. I would like to create clustered or non-clustered index.
What is the quick way to create? I have tried once and it took more than 10 min.
please help.
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Jan 19, 2008
Hello, I will explain myself further. I want to make my table in such a way that no two colums have the same value for example:
Row 1 - Column 1 = "cool"
Row 1 - Column 3 = 91
Row 3 - Column 1 = "cool"
Row 3 - Column 3 = 91
I dont care about one column having duplicate values, I want to protect against Column 1 and 3 having the same values on other rows. Is this possible to do in sql server?
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Nov 12, 2001
I'm looking for a query that will return all index names, the table the index is on and the columns in the index...
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Nov 20, 2005
Hello all,
how can I select one or more columns from a table by column-index and NOT by columnname?
e.g.:
SELECT tbl1.[1], tbl1.[2], tbl1.[3] FROM Orders AS tbl1
and NOT like this:
SELECT tbl1.OrderNo, tbl1.ProductNo, tbl1.Price FROM Orders AS tbl1
Is that possible in MS-SQL 2000?
Thanks a lot in advance
kind regards
Otto
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Jan 30, 2008
Hi,
SQL Server 2005 has a new very useful feature for creating non-clustered indexes called INCLUDE <columns> which are very helpful when trying to create covering indexes.
Does anyone know of a way to retrieve these INCLUDE columns through any of the system metadata tables? The sp_helpIndex stored procedure is what I currently use but that only returns the (sorted) index columns and not the include columns.
Thanks in advance,
Gordon Radley
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Sep 8, 2006
Hi there, I have a table that has an IDENTITY column and it is the PK of this table. By default SQL Server creates a unique clustered index on the PK, but this isn't what I wanted. I want to make a regular unique index on the column so I can make a clustered index on a different column.
If I try to uncheck the Clustered index option in EM I get a dialog that says "Cannot convert a clustered index to a nonclustered index using the DROP_EXISTING option.". If I simply try to delete the index I get the following "An explicit DROP INDEX is not allowed on index 'index name'. It is being used for PRIMARY KEY constraint enforcement.
So do I have to drop the PK constraint now? How does that affect all the tables that have FK relationships to this table?
Thanks
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Jul 9, 2015
Does including non-key columns work for the performance of an index?
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Jul 28, 2015
I used following query to identify missing indexes:
SELECT mid.statement , mid.included_columns, mid.equality_columns, mid.inequality_columns,
migs.avg_total_user_cost * (migs.avg_user_impact / 100.0) * (migs.user_seeks + migs.user_scans) AS improvement_measure,
'CREATE INDEX [NCIX_' + CONVERT (varchar, mig.index_group_handle) + '_' + CONVERT (varchar, mid.index_handle)
+ '_' + LEFT (PARSENAME(mid.statement, 1), 32) + ']'
+ ' ON ' + mid.statement
[Code] ....
I think I need to only create few if an index is covering all columns then I do not need to create more indexes for separate columns or should I create separate index as suggested?
Similarly:
CREATE INDEX [NCIX_20187_20186_TL_SRV_Stationary_Stock_Transact] ON [TL_SRV_Stationary_Stock_Transaction] ([SerialNo],[StationaryStatus]) GO
CREATE INDEX [NCIX_20189_20188_TL_SRV_Stationary_Stock_Transact] ON [TL_SRV_Stationary_Stock_Transaction] ([StationaryStatus]) INCLUDE ([SerialNo]) GO
[Code] ....
Should I create all indexes above or use minimum number of indexes which covers all columns as mentioned in above create index statements?
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