Clustered Index On Nvarchar Column Or Int...

Jan 25, 2007

Users can approach their userprofile on my site using: www.mysite.com/name=peter
Name is a unique value within my database (db type: nvarchar(50))

Now, I have created a clustered index on the username column.
However, IMHO its faster to create a clustered index on the (also unique) usercode column since that is of type int.

BUT since a user can approach my site based on username I feel that I HAVE to live with this setback in performance....

Is that true or is there a better way to solve this issue?

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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










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Simple Query Chooses Clustered Index Scan Instead Of Clustered Index Seek

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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I have a database where records are Inserted by an external process.
There is no updating or deleting of the data once inserted. The table in
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manufacturing processes). Each record bears a start and end time. Most
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I want to add an index on the Start Time, the Downtime Cause, and the
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My question is: should this new index also contain the Machine_id column
or does the existence of the Clustered Index already on that column negate
its need in the new index?

RC - Dedicated to only creating original mistakes!

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Want to check my thinking with you folks...

I have a table with a clustered composite index, consisting of 3 columns, which together form a unique key. For illustration, the columns are C1, C2 & C3.

Counts of distinct values for columns are C1 425, C2 300,000 & C3 4,000,000

C3 is effectively number of seconds since 01/01/1970.

The usage of the table is typically, insert a row, do something else, then update it.

Currently, the index columns are ordered C3,C1,C2. Fill factor of 90%.

My thinking is that this composite index is better ordered C1,C2,C3.

My reasoning is that having C3 as the leading column, biases all the inserts towards one side of the indexes underlying B-tree, causing page splits. Also, there'll be a bunch of "wasted" space across the tree, as the values going into C3 only ever get bigger (like an identity), so the space due to the fill factor in lower values never gets used.

Welcome your thoughts.

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I created composite clustered index key based on Gender and Salary column 

The Query executed Successfully and <g class="gr_ gr_135 gr-alert gr_tiny gr_spell undefined ContextualSpelling multiReplace" data-gr-id="135" id="135">i</g>

got composite index key id Gender(-), Salary I <g class="gr_ gr_310 gr-alert gr_gramm undefined Grammar only-ins replaceWithoutSep" data-gr-id="310" id="310">want</g> know why Gender(-) display like this?

And Gender is <g class="gr_ gr_391 gr-alert gr_spell undefined ContextualSpelling ins-del multiReplace" data-gr-id="391" id="391">nvarchar</g> (20) 

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I would like to put a Clustered Index on a date column in a current heap, but one question/concern.This heap every month has thousands of rows deleted and even more added later. How much of an issue will this cause the Clustered Index as far as page splits? I was thinking Fill Factor of 70%.I would normally just test and still will on Dev box, but my Dev box is much smaller than production as far as power.

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I am extremely new to database design, and I ran into a problem that I know comes up often, however has many opinions...

Basically I have a table that is going to have 50+ columns. The natural key on this table is actually 8 columns wide, 4 of them being Varchar columns by default. (varchar(50)'s).

I have added an identity column, (1,1) to the table, however I put the clustered index on the 8 natural keys... My plan is to rebuild the clustered index once nightly when the system isn't in use (after 7 pm).

I know others would say it would be better to have the clustered key on the 1,1 column and then add indexes on the other 8 fields... However I don't quite understand why honestly...

Every single query against this table will use the 8 columns, and will NOT use the Identity column (1,1) because they are calls from other systems that do not know the Identity column....

Therefore if your database is set up for query speed, and every single query has to have a value for 8 columns to get a valid result, does it make sense to put a clustered index over the 8 columns?

If not why? Why is putting a clustered index on an identity column (that will literally never be used in a query) a better solution?

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Oct 9, 2015

I am trying to use an indexed view to allow for aggregations to be generated more quickly in my test data warehouse. The Fact Table I am creating the indexed view on is a partitioned clustered columnstore index.

I have created a view with the following code:

ALTER view dbo.FactView
with schemabinding
as
select local_date_key, meter_key, unit_key, read_type_key, sum(isnull(read_value,0)) as [s_read_value], sum(isnull(cost,0)) as [s_cost]
, sum(isnull(easy_target_value,0)) as [s_easy_target_value], sum(isnull(hard_target_value,0)) as [s_hard_target_value]
, sum(isnull(read_value,0)) as [a_read_value], sum(isnull(temperature,0)) as [a_temp], sum(isnull(co2,0)) as [s_co2]
, sum(isnull(easy_target_co2,0)) as [s_easy_target_co2]
, sum(isnull(hard_target_co2,0)) as [s_hard_target_co2], sum(isnull(temp1,0)) as [a_temp1], sum(isnull(temp2,0)) as [a_temp2]
, sum(isnull(volume,0)) as [s_volume], count_big(*) as [freq]
from dbo.FactConsumptionPart
group by local_date_key, read_type_key, meter_key, unit_key

I then created an index on the view as follows:

create unique clustered index IDX_FV on factview (local_date_key, read_type_key, meter_key, unit_key)

I then followed this up by running some large calculations that required use of the aggregation functionality on the main fact table, grouping by the clustered index columns and only returning averages and sums that are available in the view, but it still uses the underlying table to perform the aggregations, rather than the view I have created. Running an equivalent query on the view, then it takes 75% less time to query the indexed view directly, to using the fact table. I think the expected behaviour was that in SQL Server Enterprise or Developer edition (I am using developer edition), then the fact table should have used the indexed view. what I might be missing, for the query not to be using the indexed view?

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Jul 11, 2007

Hi, I was wondering if any SQL Server gurus out there could help me...I have a table I'm trying to apply a full text catalog to, however no results are ever returned due to the text column being cataloged being of varbinary(max) that's being populated from a converted nvarchar(max) value - I've narrowed it down to this specifically, populating with non nvarchar text seems to work fine.To re-create the problem quickly...If I populate the column viaCONVERT(varbinary(max), 'test text')then there is no problem, I get results as expected.However if I populate the column viaCONVERT(varbinary(max), CAST('test text' as nvarchar(max)))no results are ever returned.Is this a bug with SQL Server 2005 Full Text Indexing? I'm happily creating full text catalogs when an nvarchar is not getting converted into a varbinary.I'm setting the Document Type column to '.html' (I've tried changing this to '.txt' in case it was a fault with the html ifilter but the problem persists so I believe I can rule this out).The reason I need to convert an nvarchar to varbinary is that the table holds multi-lingual text and I'm adding a html meta tag <META NAME="MS.LOCALE" CONTENT="ES"> to the beginning in order for the full text indexing word breaker to select the correct language to catalog the text with. The aim being to provide more relevant searches in users native languages (I've read a few articles that describe this technique, but it's the first time I've tried to apply it).Any pointers / suggestions would be greatly appreciated. Cheers,Gavin.

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SQL 2005 Bug? Cannot Create Full Text Index For Varbinary Column That's Populated From Converted Nvarchar Values

Jul 11, 2007

Hi, I was wondering if any SQL Server gurus out there could help me...

I have a table I'm trying to apply a full text catalog to, however no results are ever returned due to the text column being cataloged being of varbinary(max) that's being populated from a converted nvarchar(max) value.

To re-create the problem quickly...

If I populate the column via
CONVERT(varbinary(max), 'test text')
then there is no problem, I get results as expected.

However if I populate the column via
CONVERT(varbinary(max), CAST('test text' as nvarchar(max)))
no results are ever returned.

Is this a bug with SQL Server 2005 Full Text Indexing? I'm happily creating full text catalogs when an nvarchar is not getting converted into a varbinary.

I'm setting the Document Type column to '.html' (I've tried changing this to '.txt' in case it was a fault with the html ifilter but the problem persists so I believe I can rule this out).

The reason I need to convert an nvarchar to varbinary is that the table holds multi-lingual text and I'm adding a html meta tag <META NAME="MS.LOCALE" CONTENT="ES"> to the beginning in order for the full text indexing word breaker to select the correct language to catalog the text with. The aim being to provide more relevant searches in users native languages (I've read a few articles that describe this technique, but it's the first time I've tried to apply it).

Any pointers / suggestions would be greatly appreciated. Cheers,
Gavin.

UPDATE: Below is a T-SQL script you can run to demonstrate the effect I'm experiencing...




Code Snippet

-- Create test database
CREATE DATABASE FullTextTest
GO
USE FullTextTest
GO

-- Create test data table
CREATE TABLE TestTable
(
pk UNIQUEIDENTIFIER NOT NULL CONSTRAINT tablePK PRIMARY KEY,
varbinarycol VARBINARY(MAX),
documentExtension VARCHAR(5),
)
GO

-- The below single entry WILL BE FOUND (the text source is being entered directly)
INSERT INTO TestTable (pk, varbinarycol, documentExtension) VALUES (NEWID(), CONVERT(VARBINARY(MAX),'<META NAME="MS.LOCALE" CONTENT="EN">test entry 1'), '.html')

-- The bellow two entries below WILL NOT BE FOUND (the text source is taken from an NVARCHAR(MAX) value)
INSERT INTO TestTable (pk, varbinarycol, documentExtension) VALUES (NEWID(), CONVERT(VARBINARY(MAX), CAST('<META NAME="MS.LOCALE" CONTENT="EN">test entry 2' AS NVARCHAR(MAX))), '.html')
INSERT INTO TestTable (pk, varbinarycol, documentExtension) VALUES (NEWID(), CONVERT(VARBINARY(MAX), CAST('<META NAME="MS.LOCALE" CONTENT="EN">test entry 3' AS NVARCHAR(MAX))), '.html')
GO

-- Create the full text catalog
sp_fulltext_database 'enable'
GO
CREATE FULLTEXT CATALOG TEST AS DEFAULT
GO
CREATE FULLTEXT INDEX ON TestTable (varbinarycol TYPE COLUMN documentExtension LANGUAGE 1033)
KEY INDEX tablePK
GO

-- NOTE: You might need to give the catalog a chance to build before running the script below.

-- Now do a search that SHOULD RETURN 3 ROWS of data, but ONLY 1 ROW IS RETURNED
SELECT CAST(varbinarycol AS NVARCHAR(MAX)) FROM TestTable WHERE CONTAINS(varbinarycol, 'test')

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Sep 4, 2015

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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,

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Jan 4, 2008

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Sep 8, 2006

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Oct 15, 2007

Hi 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!
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I want to know whether this will slow down,insert and update on the <table1>?

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Hi everyone,
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Thanks

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Will the resulting index keys on this new NC index effectively be:

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OR
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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.

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I am kind of confused on why you would use full text index as opposed to clustered index.

Thank you
Goldmember

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Hi,
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In Microsoft SQL Management Studio 2005 I have the ability to add a single non clustered index on a table on multiple columns (ordered how I want) AND/OR I may create a multiple of these non-clustered Index entries with a single column per non-clustered index.

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