What Is Covering Index?
Feb 29, 2008View 3 Replies
ADVERTISEMENT
Help On Creating A Covering Index????
Apr 2, 2007Hi,
Trying to optimize a query but not sure what to do. I have this query on which I ran an exec plan,
SET NOCOUNT ON;
SELECT qaTestSuite.TestSuiteID, qaTestSuite.TestSuiteStart, qaTestSuite.TestInterface, qaTestSuite.TestVersion, qaTests.TestMachine, qaTestSuite.TestClientMachine, qaTests.TestLogin, qaTests.TestLabel,
qaTestSuite.TestCLPs, qaTestSuite.TestSuiteEnd, qaTests.TestID, qaTests.TestIDInternal, qaTests.TestStart,
qaTests.TestName, qaTests.TestTier, qaTests.TestNo, qaTests.TestWFBCalled, qaTests.TestWFBTime,
qaTests.TestSearches, qaTests.TestSearchesTime, qaTests.TestResult, qaTests.TestEnd, qaTestMssgs.TestMssgsID,
qaTestMssgs.TestMssgTime, qaTestMssgs.TestMssgType, qaTestMssgs.TestMessage, qaTestSuite.TestMode
FROM qaTestSuite with(NOLOCK) INNER JOIN
qaTests with(NOLOCK) ON qaTestSuite.TestSuiteID = qaTests.TestSuiteID INNER JOIN
qaTestMssgs with(NOLOCK) ON qaTests.TestID = qaTestMssgs.TestID
order by qaTestSuite.TestSuiteStart DESC
and it gives me the following results:
Use a Bookmark (RID or Clustering Key) to look up the corresponding row in the Table or Clustered Index.
Physical Op: Bookmark Lookup
Logical Op: Bookmark Lookup
Est. Row Count: 128
Est. Row Size: 4760
Est. I/O Cost: 0.368
Est. CPU Cost: 0.000141
Est. Execs: 1.0
Est. Cost: 0.368888(89%)
Est. Subtree Cost:.415
Argument:
BOOKMARK:([Bmk1004]), OBJECT:([QAMaster].[dbo].[qaTestMssgs]) WITH PREFETCH
I have no idea what to do with that. Anyone have any clues? What I found online was that I should make a Covering Index, but I didn't find
any patterns on how to do that. Any one have ideas of how to do this?
Thanks very much for your help!
--PhB
How To Create A Covering Index
May 15, 2008I have a table there is a query which has bad performance. This query normally can not use index because a lot of 'IS NULL','OR','LIKE' USED in where clause. I want to create a covering index for this query so it can use index scan only rather than Processor had to look up the row columns it needs
from a table or a clustered index.
current there are two index apply on that table:
CREATE UNIQUE CLUSTERED INDEX [Person_RecordID_UIX] ON Person
(
[RecordID] ASC
)
go
ALTER TABLE [Person] ADD CONSTRAINT Person_PK PRIMARY KEY NONCLUSTERED
(
[EntityID] ASC
)
How to add a covering index for the columns such as familyName,givenName, dob. All of these columns are not too much high selective.
Can I do like the following :
--create third index
CREATE NONCLUSTERED INDEX [Person_Cover_IX] ON [dbo].[Person]
(
[EntityID] ASC
)
INCLUDE ( [FamName],
[FirstName],
[DOB],
[Gender]
)
Or DROP Current index on entityid and recreate it with include clause.
What's the different between these two.
Thank you.
Fulltext Index Is Not Covering All Entries
Dec 5, 2007Hello,
i have a database with about 300.000 entries. The database gets about 30 new entries every day. The Database has an FulltextIndex on several columns. This FulltextIndex will be updated every night.
But now i have found out, that the fulltextsearch doesn't work anymore for all entries that where added after April 2006.
When i for example make following sql-statementSELECT id,date FROM MyTable WHERE (CONTAINS((columnA),' "mykeyword" '))
i only get results that have a date after April 2006 (although there are matching entries after that date).
What can the reason for that be?
According to Management Studio the last Update of the FulltextCatalog has been made on 1st of December 2007. Everything looks normal and I didn't find any logs that are saying that there has been any errors.
Where do I have to look to be sure if the FullTextIndex does work?
Specs:
SQL Server 2005
Microsoft SQL Server Management Studio 9.00.1399.00Microsoft Analysis Services-Clienttools 2005.090.1399.00Microsoft Data Access Components (MDAC) 2000.086.3959.00 (srv03_sp2_rtm.070216-1710)Microsoft MSXML 2.6 3.0 6.0 Microsoft Internet Explorer 6.0.3790.3959Microsoft .NET Framework 2.0.50727.832Operating System 5.2.3790
greetings
Klaus
Making Covering Index Non-key To Key Column
Jan 2, 2015I have created a covering Index like below,
----------------------------------------------------------------
CREATE NONCLUSTERED INDEX [INX_NONCLUS_COVERING_INVBAK] ON [dbo].[Invoices_Bak]
(
[SellerID] ASC, -- Key column
[BuyerID] ASC -- Key column
)
INCLUDE (
[ReceivedDate], --Non key column
[Code] ....
Above index has created on production environment, Now i would like alter above index that is from non key column to key column
You can find a non key column called [ReceivedDate] that is available in include part, i need to make this column to Key column.
How to do this proper way without affect production environment that is using unwanted disk size and more..
SQL Server 2005; Unique Constraint, Covering Index Question
Aug 9, 2006Hi,
When I create a unique constraint, SQL Server automatically creates an index on this constraint. So when I run the following...
ALTER TABLE PersonsProjects
WITH NOCHECK ADD CONSTRAINT NoDupes UNIQUE NONCLUSTERED (PersonID, ProjectID)
...SQL Server will create a composite index on PersonsProjects called NoDupes on PersonIDand ProjectID. Thing is, I need this index to include a third column Status since most queries use this column in conjunction with PersonID and ProjectID. If there was no index on this table, I would have created it as follows:
CREATE UNIQUE INDEX NoDupes ON PersonsProjects (PersonID, ProjectID) INCLUDE (Status) WITH IGNORE_DUP_KEY
But this won't enforce the unique constraint on PersonID and ProjectID when performing inserts and updates. Is there any way of creating a unique constraint with an included column?
I would rather not have two indexes...
NoDupes: PersonID,ProjectID
New Index: PersonID,ProjectID INCLUDE Status
...so I'm trying to determine what other options that might be available...please advise.
Thanks much.
Covering Indexes
Aug 1, 2006Hi,
I asked the similar question before but I have again some doubts about covering indexes.
Besides, tomorrow I have a Microsoft MCAD 70-229 exam so please help me.
In here,
SELECT * FROM Order WHERE OrderID > 12 ORDER BY OrderDate
we create composite nonclustered index for both OrderID and OrderDate column.
Leftmost is OrderID.
So
when our first research is happening(Where clause), the only
nonclustered index which is used is OrderID index. And then, when we
pass through the second search(ORDER BY clause), OrderDate index become activated.
So
we can say that the seleection of indexes in composite indexes is
determined according to the situation of the query at that time.
Hence, is this all correct ?
Best wishes,
Mert
Covering Indexes
Mar 12, 2008I plan to use covering indexes as my core tables are really huge. I wanted to check if the new feature "Included Columns" for an index is beneficial in the following scenario:
If I have a non-clustered index within the limitations of 16 fields and under 900 bytes as opposed to having 1 field with 15 included fields for the same - what is the difference in performance? Is there any advantage in using the included columns?
Multi Value Parameter And Horizontal Scroll Bar Covering Data
Jan 16, 2008I am working with a dynamically populated multi value parameter drop down list. In the case where there is only one value in the list, the horizontal scroll bar (due to the length of the value) covers up the first, and in this case only choice. The users cannot see it. This problem is only when running in report manager. It works ok in Visual Studio.
As a work around, I can add a dummy row, which then at least the users can see one row of data and then scroll down but, I would rather not do that, if there is another solution. Another option would be to set the default on the parameter so it is automatically selected but, in the case where there are many values, I do not want a default set.
Your help would be greatly appreciated.
Thanks!
Difference Between Index Seek && Index Scan && Index Lookup Operations?
Oct 20, 2006please explain the differences btween this logical & phisicall operations that we can see therir graphical icons in execution plan tab in Management Studio
thank you in advance
SQL 2012 :: Full Text Index How To Make It NOT To Index Embedded Or Attached Documents
Sep 30, 2015I am using Full Text Index to index emails stored in BLOB column in a table. Index process parses stored emails, and, if there is one or more files attached to the email these documents get indexed too. In result when I'm querying the full text index for a word or phrase I am getting reference to the email containing the word of phrase if interest if the word was used in the email body OR if it was used in any document attached to the email.
How to distinguish in a Full Text query that the result came from an embedded document rather than from "main" document? Or if that's not possible how to disable indexing of embedded documents?
My goal is either to give a user an option if he or she wants to search emails (email bodies only) OR emails AND documents attached to them, or at least clearly indicate in the returned result the real source where the word or phrase has been found.
Clustered Index On Client_ID+ORderNO+OrdersubNo, If I Create 3 Noncluster Index On Said Column Will It Imporve Performance
Dec 5, 2007
Dear All.
We had Teradata 4700 SMP. We have moved data from TD to MS_SQL SERVER 2003. records are 19.65 Millions.
table is >> Order_Dtl
Columns are:-
Client_ID varchar 10
Order_ID varchar 50
Order_Sub_ID decimal
.....
...
..
.
Pk is (ClientID+OrderId+OrderSubID)
Web Base application or PDA devices use to initiate the order from all over the country. The issue is this table is not Partioned but good HP with 30 GB RAM is installed. this is main table that receive 18,0000 hits or more. All brokers and users are using this table to see the status of their order.
The always search by OrderID, or ClientID or order_SubNo, or enter any two like (Client_ID+Order_Sub_ID) or any combination.
Query takes to much time when ever server receive more querys. some orther indexes are also created on the same table like (OrderDate, OrdCreate Date and Status)
My Question are:-
Q1. IF Person "A" query to DB on Client_ID, then what Index will use ? (If any one do Query on any two combination like Client_ID+Order_ID, So what index will be uesd.? How does MS-SQL SERVER deal with these kind of issues.?
Q2. If i create 3 more indexes on ClientID, ORderID and OrdersubID. will this improve the performance of query.if person "A" search record on orderNo so what index will be used. (Mind it their would be 3 seprate indexes for Each PK columns) and composite-Clustered index is also available.?
Q3. I want to check what indexes has been used? on what search?
Q4. How can i check what table was populated when, or last date of update (DML)?
My Limitation is i Dont Create a Partioned table. I dont have permission to do it.
In Teradata we had more than 4 tb record of CRM data with no issue. i am not new baby in db line but not expert in sql server 2003.
I am thank u to all who read or reply.
Arshad
Manager Database
Esoulconsultancy.com
(Teradata Master)
10g OCP
Integration Services :: Rebuild Index / Refresh Index And Stats Improves Ssis Package Performance
Oct 28, 2015My SSIS package is running very slow taking so much time to execute, One task is taking 2hr for inserting 100k records, i have disabled unused index still it is taking time.I am rebuilding/Refreshing indexes and stats once in month if i try to execute on daily basis will it improve my SSIS Package performance?
View 2 Replies View RelatedIndex Was Out Of Range. Must Be Non-negative And Less Than The Size Of The Collection. Parameter Name: Index
Jan 22, 2006Keep getting this error when positioning to the last page of a report.
Using Server 2003...SqlRpt Svcs 2000 sp2
Detail error msg:
Exception of type Microsoft.ReportingServices.ReportRendering.ReportRenderingException was thrown. (rrRenderingError) Get Online Help
Exception of type Microsoft.ReportingServices.ReportRendering.ReportRenderingException was thrown.
Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index
Anyone have any suggestions? Any way to find out what collection is blowing?...or where parameter name: index comes from?
Index Table1 And Select For 647.600 Records.. It Is So Slow.. But I Have No Index :)???
Jun 20, 2008hello friends
i have table1 and 200 coulumn of table1 :) i have 647.600 records. i entered my records to table1 with for step to code lines in one day :)
i select category1 category2 and category3 with select code but i have just one index.. it is productnumber and it is primarykey..So my select code lines is so slow.. it is 7-9 second.. how can i select in 0.1 second ? Should i create index for category1 and category2 and category3 ? But i dont know create index.. My select code lines is below.. Could you learn me and show me index for it ?? or Could you learn me and show me fast Select code lines and index or etc ??? Also my search code line have a dangerous releated to attaching table1 with hackers :)
cheersi send 3 value of treview1 node and childnode and child.childnode to below page.aspx :)
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not Me.IsPostBack Then
If Request("TextBox1") IsNot Nothing ThenTextBox1.Text = Request("TextBox1")
End If
If Request("TextBox2") IsNot Nothing ThenTextBox2.Text = Request("TextBox2")
End If
If Request("TextBox3") IsNot Nothing ThenTextBox3.Text = Request("TextBox3")
End If
End If
Dim searchword As String
If Request("TextBox3") = "" And Request("TextBox2") = "" Then
searchword = "Select * from urunlistesi where kategori= '" & Request("TextBox1") & "'"
End If
If Request("TextBox3") = "" Then
searchword = "Select * from urunlistesi where kategori= '" & Request("TextBox1") & "' and kategori1= '" & Request("TextBox2") & "'"
End If
If Request("TextBox3") <> "" And Request("TextBox2") <> "" And Request("TextBox1") <> "" Then
searchword = "Select * from urunlistesi where kategori= '" & Request("TextBox1") & "' and kategori1= '" & Request("TextBox2") & "' and kategori2= '" & Request("TextBox3") & "'"
End If
SqlDataSource1.SelectCommand = searchword
End Sub
The Index Entry For Row ID Was Not Found In Index ID 3, Of Table 357576312
Jul 9, 2004Hi,
I'm running a merge replication on a sql2k machine to 6 sql2k subscribers.
Since a few day's only one of the merge agents fail's with the following error:
The merge process could not retrieve generation information at the 'Subscriber'.
The index entry for row ID was not found in index ID 3, of table 357576312, in database 'PBB006'.
All DBCC CHECKDB command's return 0 errors :confused:
I'm not sure if the table that's referred to in the message is on the distribution side or the subscribers side? A select * from sysobjects where id=357576312 gives different results on both sides . .
Any ideas as to what is causing this error?
Advantages Of Using Nonclustered Index After Using Clustered Index On One Table
Jul 3, 2006Hi everyone,
When we create a clustered index firstly, and then is it advantageous to create another index which is nonclustered ??
In my opinion, yes it is. Because, since we use clustered index first, our rows are sorted and so while using nonclustered index on this data file, finding adress of the record on this sorted data is really easier than finding adress of the record on unsorted data, is not it ??
Thanks
SQL 2012 :: Clustered Index Key Order In NC Index
Mar 5, 2015I have a clustered index that consists of 3 int columns in this order: DateKey, LocationKey, ItemKey (there are many other columns in this data warehouse table such as quantities, prices, etc.).
Now I want to add a non-clustered index on just one of the other columns, say LocationKey, like this:
CREATE INDEX IX_test on TableName (LocationKey)
I understand that the clustered index keys will also be added as key columns to any NC indexes. So, in this case the NC index will also get the other two columns from the clustered index added as key columns. But, in what order will they be added?
Will the resulting index keys on this new NC index effectively be:
LocationKey, DateKey, ItemKey
OR
LocationKey, ItemKey, DateKey
Do the clustering keys get added to a NC index in the same order as they are defined in the clustered index?
Clustered Index Vs. Full Text Index
Jun 18, 2008Quick question about the primary purpose of Full Text Index vs. Clustered Index.
The Full Text Index has the purpose of being accessible outside of the database so users can query the tables and columns it needs while being linked to other databases and tables within the SQL Server instance.
Is the Full Text Index similar to the global variable in programming where the scope lies outside of the tables and database itself?
I understand the clustered index is created for each table and most likely accessed within the user schema who have access to the database.
Is this correct?
I am kind of confused on why you would use full text index as opposed to clustered index.
Thank you
Goldmember
Index/performance Index For SELECT.... IN Statement
Sep 10, 2007
Hi All,
I 'm working to improve some sql performance.
One of the major syntax inside the SELECT statment is ..
WHERE FIELDA IN (SELECT PARAVALUE FROM PARATABLE WHERE SESSIONID = "XXXXX" AND PARATYPE='A') AND
WHERE FIELDB IN (SELECT PARAVALUE FROM PARATABLE WHERE SESSIONID = "XXXXX" AND PARATYPE='B') AND
WHERE FIELDC IN (SELECT PARAVALUE FROM PARATABLE WHERE SESSIONID = "XXXXX" AND PARATYPE='C') AND
WHERE FIELDD IN (SELECT PARAVALUE FROM PARATABLE WHERE SESSIONID = "XXXXX" AND PARATYPE='D') AND
WHERE FIELDE IN (SELECT PARAVALUE FROM PARATABLE WHERE SESSIONID = "XXXXX" AND PARATYPE='E') AND
WHERE FIELDF IN (SELECT PARAVALUE FROM PARATABLE WHERE SESSIONID = "XXXXX" AND PARATYPE='F')
(It's to compare the field content with some user input parameter inside a parameter table... )
I think properly is that the SELECT ... IN is causing much slowness in the sql statement. I have indexed FIELDA , FIELDB, FILEDC etc and those PARAVALUE and PARATYPE in the PARATABLE table. But perfromance is still slow and execution takes >20 seconds for 200000 rows of records.
Do any one know if still any chance to improvide the performance like this?
Much Thanks,
Andy
Index Internals - Last Time Index Was Rebuilt?
Apr 17, 2007I'm trying to find whether there is a dmv or system view that can help me see the last time an index was rebuilt or created. Assuming I rebuilt an index using tsql commands (not a job with a history), is there a way to find out the last time that index was rebuilt?
Thanks much.
Index Scan Vs Index Seek
Mar 1, 2004I have a really strange problem.
I execute this query:
declare @cid int
set @cid = 2003227
select * from sales s, product p where p.product_Id = s.product_Id and customer_id = @cid
select * from sales s, product p where p.product_Id = s.product_Id and customer_id = @cid or @cid = 0
3 Million rows in sales, 120000 in product.
The first does and index seek, the second an index scan.
The execution plan reports that the scan takes 99.87% of the cost, and the seek takes 0.13%
This problem obviously gets worse the bigger the dataset / query /etc.
The reason I query this, is because it never used to take this long to do index scans. Is there something i can change, something i can fix?
Any help would be appreciated.
Josh
Reorganize Index And Rebuild Index ??
Mar 18, 2008Hi,
I just want to know whether any advantage or disadvantage
in doing Reorganize Index And Rebuild Index ....
Plz do comment on this ASAP !!!!
Thanks in advance
Regards
Arv
Reorganize Index And Rebuild Index
Mar 18, 2008Hi,
I just want to know whether any advantage or disadvantage
in doing Reorganize Index And Rebuild Index ....
Plz do comment on this ASAP !!!!
Thanks in advance
Regards
Arv
Clustered Index Or NonClustered Index
Apr 1, 2006Hello I want to learn disparity clustered index or nonclustered index and in queries which one run better.
example
select * from orders where orderID=5
to this query clustered or nonclustered
thanks
Simple Query Chooses Clustered Index Scan Instead Of Clustered Index Seek
Nov 14, 2006the 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?
Change Nc-index To C-index?
Jun 29, 2004Found out a while back that my facts-tabel has an non-clustered index on its facts_id. In a bunch of procedures an update is executed against a facts_id unfortunately on it's facts-table. I was wondering if changing it into a clustered index is worth the effort / would make sense considering a +110 million facts and re-indexing the other indexes as well? Facts are loaded sequentially, so I would suspect them facts are in the ordered already?
thanx,
Index Seek, Index Scan, Table Scan
Oct 4, 2007
Hey,
what is the difference between Table Scan und Index Scan?
I find no difitions in the internet
Finchen
What Is Table Scan, Index Scan And Index Seek??
Sep 21, 2007Hi,
I want to know wht is a
TABLE SCAN
INDEX SCAN
INDEX SEEKand When they are used, Wht is the difference between all these.????
Include Clustered Index In Non-clustered Index?
Oct 15, 2007Hi everybody!
I just ran the Database Engine Tuning Advisor on a relative complex query to find out if a new index might help, and in fact it found a combination that should give a performance gain of 94%. Fair enough to try that.
What I wonder about: The index I should create contains 4 columns, the last of them being the Primary Key column of the table, which is also my clustered index for the table. It is an identity integer btw.
I think I remember that ANY index does include the clustered one as lookup into the data, so having it listed to the list of columns will not help. It might at worst add another duplicate 4 bytes to each index entry.
Right? Wrong? Keep the column in the index, or remove it since it is included implicit anyway?
Thanks for suggestions!
Ralf
Index Help
Jun 27, 2001Hello List,
I've couple of tables in my database. I created some clustered indexes and non-clustered indexes on these tables. But surprisingly, When I run sp_helpindex table_name, I see a lot of indexes starting from WA_ name. I dont know, what are these indexes and I believe, I havent created them.
Would like to know, how does these got created and is it appropriate to delete them?
Please advice
Thanks in advance
Sindi
Need Help With Index
Aug 1, 2001I have table pcCode
sp_help pcCode
Column_name
-----------
ID_Code
CodeType
ID_Property
ID_Reference
Name
ShortName
ViewOrder
ParentType
Status
index_description index_keys
------------------------------------------------------------------------------clustered, unique, primary key located on PRIMARY ID_Code
nonclustered, unique key located on PRIMARY ID_Property, CodeType, ShortName
Now
if I do
select Status from prcode where ID_Property = 7
Will SQl server use index created on 3 columns (becouse ID_Property first in the index )
or I need another index on ID_Property column only
Thanks
Index
Sep 7, 2001This index "_WA_Sys_title_318258D2" was auto created by the system (nonclustered, statistics, auto create located on Primary). If I want
it remove will I have to drop the table because the command Drop index...
doesn't remove it, the message "because it does not exist in the system catalog." will come up and were can I turn of the command so it won't be create by the system ?