index and key: design

Showing posts with label design. Show all posts

Friday, March 30, 2012

Index Speed use of REPLACE in clause

I have a frequently run Query, due to the design of the Sproc the indexed
columns I have added to support these are being used but are slow due to the
fact the use of the REPLACE in the Clause (Replace is being used to remove
spaces)
I.E
Select <columns>
FROM <Table>
WHERE
(sEMail1 = 'hambly_neil@.hotmail.com' OR sEMail2 = ''hambly_neil@.hotmail.com')
OR
(REPLACE(sTel1,' ','') = '0123456789' AND REPLACE(sPostCode,' ','') = 'N118HQ')
Does anyone have any ideas on recoding or indexes changes to help here
--
Neil HamblyHow about cleansing the data on the way in (i.e. when you INSERT it, run the
REPLACE), so that you won't have to do it every time you query?
Adam Machanic
SQL Server MVP
http://www.sqljunkies.com/weblog/amachanic
--
"Neil Hambly" <hambly_neil@.hotmail.com> wrote in message
news:3D4000CA-7EFE-4A9F-AF74-3F0F6CB465EF@.microsoft.com...
> I have a frequently run Query, due to the design of the Sproc the indexed
> columns I have added to support these are being used but are slow due to
the
> fact the use of the REPLACE in the Clause (Replace is being used to remove
> spaces)
> I.E
> Select <columns>
> FROM <Table>
> WHERE
> (sEMail1 = 'hambly_neil@.hotmail.com' OR sEMail2 => ''hambly_neil@.hotmail.com')
> OR
> (REPLACE(sTel1,' ','') = '0123456789' AND REPLACE(sPostCode,' ','') => 'N118HQ')
> Does anyone have any ideas on recoding or indexes changes to help here
> --
> Neil Hambly|||This would be the ideal scenario of course, unofrtunately due to Data-Privacy
and other reasons, the data cannot be Cleansed
One thought I had was the use of Computed colums - do not know if this would
be suitable for this type of issue
"Adam Machanic" wrote:
> How about cleansing the data on the way in (i.e. when you INSERT it, run the
> REPLACE), so that you won't have to do it every time you query?
>
> --
> Adam Machanic
> SQL Server MVP
> http://www.sqljunkies.com/weblog/amachanic
> --
>
> "Neil Hambly" <hambly_neil@.hotmail.com> wrote in message
> news:3D4000CA-7EFE-4A9F-AF74-3F0F6CB465EF@.microsoft.com...
> > I have a frequently run Query, due to the design of the Sproc the indexed
> > columns I have added to support these are being used but are slow due to
> the
> > fact the use of the REPLACE in the Clause (Replace is being used to remove
> > spaces)
> > I.E
> > Select <columns>
> > FROM <Table>
> > WHERE
> > (sEMail1 = 'hambly_neil@.hotmail.com' OR sEMail2 => > ''hambly_neil@.hotmail.com')
> > OR
> > (REPLACE(sTel1,' ','') = '0123456789' AND REPLACE(sPostCode,' ','') => > 'N118HQ')
> >
> > Does anyone have any ideas on recoding or indexes changes to help here
> >
> > --
> > Neil Hambly
>
>|||Possibly, yes. You can index computed columns to semi-persist them, as well
(they'll be persisted in the index); in this case, you could do:
ALTER TABLE YourTable
ADD Tel1NoSpace AS (REPLACE(sTel1, ' ', ''))
ALTER TABLE YourTable
ADD PostCodeNoSpace AS (REPLACE(sPostCode, ' ', ''))
CREATE NONCLUSTERED INDEX IX_TelPostSearch ON YourTable (Tel1NoSpace,
PostCodeNoSpace)
... That would solve your issue, I think. But _better_ would still be to
cleanse the data -- I'm not sure what you mean by data privacy; the data is
in your database already, isn't it?
Adam Machanic
SQL Server MVP
http://www.sqljunkies.com/weblog/amachanic
--
"Neil Hambly" <hambly_neil@.hotmail.com> wrote in message
news:40183D6E-BAD0-4A2E-A474-26B6DD25E763@.microsoft.com...
> This would be the ideal scenario of course, unofrtunately due to
Data-Privacy
> and other reasons, the data cannot be Cleansed
> One thought I had was the use of Computed colums - do not know if this
would
> be suitable for this type of issue
> "Adam Machanic" wrote:
> > How about cleansing the data on the way in (i.e. when you INSERT it, run
the
> > REPLACE), so that you won't have to do it every time you query?
> >
> >
> > --
> > Adam Machanic
> > SQL Server MVP
> > http://www.sqljunkies.com/weblog/amachanic
> > --
> >
> >
> > "Neil Hambly" <hambly_neil@.hotmail.com> wrote in message
> > news:3D4000CA-7EFE-4A9F-AF74-3F0F6CB465EF@.microsoft.com...
> > > I have a frequently run Query, due to the design of the Sproc the
indexed
> > > columns I have added to support these are being used but are slow due
to
> > the
> > > fact the use of the REPLACE in the Clause (Replace is being used to
remove
> > > spaces)
> > > I.E
> > > Select <columns>
> > > FROM <Table>
> > > WHERE
> > > (sEMail1 = 'hambly_neil@.hotmail.com' OR sEMail2 => > > ''hambly_neil@.hotmail.com')
> > > OR
> > > (REPLACE(sTel1,' ','') = '0123456789' AND REPLACE(sPostCode,' ','') => > > 'N118HQ')
> > >
> > > Does anyone have any ideas on recoding or indexes changes to help here
> > >
> > > --
> > > Neil Hambly
> >
> >
> >|||Yes, a little test on the Northwind database suggests that this should
work (provided you are using Enterprise Edition).
Gert-Jan
Neil Hambly wrote:
> This would be the ideal scenario of course, unofrtunately due to Data-Privacy
> and other reasons, the data cannot be Cleansed
> One thought I had was the use of Computed colums - do not know if this would
> be suitable for this type of issue
> "Adam Machanic" wrote:
> > How about cleansing the data on the way in (i.e. when you INSERT it, run the
> > REPLACE), so that you won't have to do it every time you query?
> >
> >
> > --
> > Adam Machanic
> > SQL Server MVP
> > http://www.sqljunkies.com/weblog/amachanic
> > --
> >
> >
> > "Neil Hambly" <hambly_neil@.hotmail.com> wrote in message
> > news:3D4000CA-7EFE-4A9F-AF74-3F0F6CB465EF@.microsoft.com...
> > > I have a frequently run Query, due to the design of the Sproc the indexed
> > > columns I have added to support these are being used but are slow due to
> > the
> > > fact the use of the REPLACE in the Clause (Replace is being used to remove
> > > spaces)
> > > I.E
> > > Select <columns>
> > > FROM <Table>
> > > WHERE
> > > (sEMail1 = 'hambly_neil@.hotmail.com' OR sEMail2 => > > ''hambly_neil@.hotmail.com')
> > > OR
> > > (REPLACE(sTel1,' ','') = '0123456789' AND REPLACE(sPostCode,' ','') => > > 'N118HQ')
> > >
> > > Does anyone have any ideas on recoding or indexes changes to help here
> > >
> > > --
> > > Neil Hambly
> >
> >
> >|||"Gert-Jan Strik" <sorry@.toomuchspamalready.nl> wrote in message
news:41C22D18.3AE1AF4E@.toomuchspamalready.nl...
> Yes, a little test on the Northwind database suggests that this should
> work (provided you are using Enterprise Edition).
What's Enterprise Edition have to do with it?
--
Adam Machanic
SQL Server MVP
http://www.sqljunkies.com/weblog/amachanic
--|||Re: Data privacy act - We do not own all the data some of it is supplied by
our clients.
Anyway I built some computed columns with the formula using Replace(sTel1, '
', '') etc..Created indexes on these columns and amended my Sprocs to use the
computed columns etc.. Went from 10 secs (22, 000 logical reads) to a few ms
with 12 logical reads..
As this is run over 300,000 times per month that is a huge perf impact
Thanks for your posts
"Adam Machanic" wrote:
> Possibly, yes. You can index computed columns to semi-persist them, as well
> (they'll be persisted in the index); in this case, you could do:
> ALTER TABLE YourTable
> ADD Tel1NoSpace AS (REPLACE(sTel1, ' ', ''))
> ALTER TABLE YourTable
> ADD PostCodeNoSpace AS (REPLACE(sPostCode, ' ', ''))
> CREATE NONCLUSTERED INDEX IX_TelPostSearch ON YourTable (Tel1NoSpace,
> PostCodeNoSpace)
>
> ... That would solve your issue, I think. But _better_ would still be to
> cleanse the data -- I'm not sure what you mean by data privacy; the data is
> in your database already, isn't it?
>
> --
> Adam Machanic
> SQL Server MVP
> http://www.sqljunkies.com/weblog/amachanic
> --
>
> "Neil Hambly" <hambly_neil@.hotmail.com> wrote in message
> news:40183D6E-BAD0-4A2E-A474-26B6DD25E763@.microsoft.com...
> > This would be the ideal scenario of course, unofrtunately due to
> Data-Privacy
> > and other reasons, the data cannot be Cleansed
> > One thought I had was the use of Computed colums - do not know if this
> would
> > be suitable for this type of issue
> >
> > "Adam Machanic" wrote:
> >
> > > How about cleansing the data on the way in (i.e. when you INSERT it, run
> the
> > > REPLACE), so that you won't have to do it every time you query?
> > >
> > >
> > > --
> > > Adam Machanic
> > > SQL Server MVP
> > > http://www.sqljunkies.com/weblog/amachanic
> > > --
> > >
> > >
> > > "Neil Hambly" <hambly_neil@.hotmail.com> wrote in message
> > > news:3D4000CA-7EFE-4A9F-AF74-3F0F6CB465EF@.microsoft.com...
> > > > I have a frequently run Query, due to the design of the Sproc the
> indexed
> > > > columns I have added to support these are being used but are slow due
> to
> > > the
> > > > fact the use of the REPLACE in the Clause (Replace is being used to
> remove
> > > > spaces)
> > > > I.E
> > > > Select <columns>
> > > > FROM <Table>
> > > > WHERE
> > > > (sEMail1 = 'hambly_neil@.hotmail.com' OR sEMail2 => > > > ''hambly_neil@.hotmail.com')
> > > > OR
> > > > (REPLACE(sTel1,' ','') = '0123456789' AND REPLACE(sPostCode,' ','') => > > > 'N118HQ')
> > > >
> > > > Does anyone have any ideas on recoding or indexes changes to help here
> > > >
> > > > --
> > > > Neil Hambly
> > >
> > >
> > >
>
>|||I could be wrong. I thought that maybe indexes on computed columns would
not be automatically used in Standard Edition, just as indexes on views
are not automatically used (unless you use Enterprise Edition or provide
special hints).
But as I said: I could be wrong. Maybe someone with Standard Edition can
test this example to see if an index seek is used.
USE Northwind
GO
ALTER TABLE Customers ADD CompanyNameNoSpace AS
Replace(CompanyName,space(1),'')
GO
CREATE INDEX IX_Customers_CompanyNameNoSpace ON
Customers(CompanyNameNoSpace)
GO
SET SHOWPLAN_TEXT ON
GO
SELECT * FROM Customers WHERE CompanyNameNoSpace='EasternConnection'
GO
SET SHOWPLAN_TEXT OFF
Gert-Jan
Adam Machanic wrote:
> "Gert-Jan Strik" <sorry@.toomuchspamalready.nl> wrote in message
> news:41C22D18.3AE1AF4E@.toomuchspamalready.nl...
> > Yes, a little test on the Northwind database suggests that this should
> > work (provided you are using Enterprise Edition).
> What's Enterprise Edition have to do with it?
> --
> Adam Machanic
> SQL Server MVP
> http://www.sqljunkies.com/weblog/amachanic
> --|||Confirmed:
Microsoft SQL Server 2000 - 8.00.760 (Intel X86) Dec 17 2002 14:22:05
Copyright (c) 1988-2003 Microsoft Corporation Standard Edition on Windows
NT 5.0 (Build 2195: Service Pack 4)
|--Compute
Scalar(DEFINE:([Customers].[CompanyNameNoSpace]=replace([Customers].[Company
Name], Convert(space(1)), Convert(''))))
|--Bookmark Lookup(BOOKMARK:([Bmk1000]),
OBJECT:([Northwind].[dbo].[Customers]))
|--Index
Seek(OBJECT:([Northwind].[dbo].[Customers].[IX_Customers_CompanyNameNoSpace]
), SEEK:([Customers].[CompanyNameNoSpace]=Convert([@.1])) ORDERED FORWARD)
:-)
--
Adam Machanic
SQL Server MVP
http://www.sqljunkies.com/weblog/amachanic
--
"Gert-Jan Strik" <sorry@.toomuchspamalready.nl> wrote in message
news:41C2E4BC.868B93CB@.toomuchspamalready.nl...
> I could be wrong. I thought that maybe indexes on computed columns would
> not be automatically used in Standard Edition, just as indexes on views
> are not automatically used (unless you use Enterprise Edition or provide
> special hints).
> But as I said: I could be wrong. Maybe someone with Standard Edition can
> test this example to see if an index seek is used.
> USE Northwind
> GO
> ALTER TABLE Customers ADD CompanyNameNoSpace AS
> Replace(CompanyName,space(1),'')
> GO
> CREATE INDEX IX_Customers_CompanyNameNoSpace ON
> Customers(CompanyNameNoSpace)
> GO
> SET SHOWPLAN_TEXT ON
> GO
> SELECT * FROM Customers WHERE CompanyNameNoSpace='EasternConnection'
> GO
> SET SHOWPLAN_TEXT OFF
> Gert-Jan
> Adam Machanic wrote:
> >
> > "Gert-Jan Strik" <sorry@.toomuchspamalready.nl> wrote in message
> > news:41C22D18.3AE1AF4E@.toomuchspamalready.nl...
> > > Yes, a little test on the Northwind database suggests that this should
> > > work (provided you are using Enterprise Edition).
> >
> > What's Enterprise Edition have to do with it?
> >
> > --
> > Adam Machanic
> > SQL Server MVP
> > http://www.sqljunkies.com/weblog/amachanic
> > --|||Thanks,
Gert-Jan
Adam Machanic wrote:
> Confirmed:
> Microsoft SQL Server 2000 - 8.00.760 (Intel X86) Dec 17 2002 14:22:05
> Copyright (c) 1988-2003 Microsoft Corporation Standard Edition on Windows
> NT 5.0 (Build 2195: Service Pack 4)
> |--Compute
> Scalar(DEFINE:([Customers].[CompanyNameNoSpace]=replace([Customers].[Company
> Name], Convert(space(1)), Convert(''))))
> |--Bookmark Lookup(BOOKMARK:([Bmk1000]),
> OBJECT:([Northwind].[dbo].[Customers]))
> |--Index
> Seek(OBJECT:([Northwind].[dbo].[Customers].[IX_Customers_CompanyNameNoSpace]
> ), SEEK:([Customers].[CompanyNameNoSpace]=Convert([@.1])) ORDERED FORWARD)
> :-)
> --
> Adam Machanic
> SQL Server MVP
> http://www.sqljunkies.com/weblog/amachanic
> --
> "Gert-Jan Strik" <sorry@.toomuchspamalready.nl> wrote in message
> news:41C2E4BC.868B93CB@.toomuchspamalready.nl...
> > I could be wrong. I thought that maybe indexes on computed columns would
> > not be automatically used in Standard Edition, just as indexes on views
> > are not automatically used (unless you use Enterprise Edition or provide
> > special hints).
> >
> > But as I said: I could be wrong. Maybe someone with Standard Edition can
> > test this example to see if an index seek is used.
> >
> > USE Northwind
> > GO
> > ALTER TABLE Customers ADD CompanyNameNoSpace AS
> > Replace(CompanyName,space(1),'')
> > GO
> > CREATE INDEX IX_Customers_CompanyNameNoSpace ON
> > Customers(CompanyNameNoSpace)
> > GO
> > SET SHOWPLAN_TEXT ON
> > GO
> > SELECT * FROM Customers WHERE CompanyNameNoSpace='EasternConnection'
> > GO
> > SET SHOWPLAN_TEXT OFF
> >
> > Gert-Jan
> >
> > Adam Machanic wrote:
> > >
> > > "Gert-Jan Strik" <sorry@.toomuchspamalready.nl> wrote in message
> > > news:41C22D18.3AE1AF4E@.toomuchspamalready.nl...
> > > > Yes, a little test on the Northwind database suggests that this should
> > > > work (provided you are using Enterprise Edition).
> > >
> > > What's Enterprise Edition have to do with it?
> > >
> > > --
> > > Adam Machanic
> > > SQL Server MVP
> > > http://www.sqljunkies.com/weblog/amachanic
> > > --|||Actually, I just took a closer look at the execution plan. Interesting that
CompanyNameNoSpace is being re-computed after the bookmark lookup, even
though it was used for the initial index seek! I'm surprised that SQL
Server can't use the value from the index...
--
Adam Machanic
SQL Server MVP
http://www.sqljunkies.com/weblog/amachanic
--
"Adam Machanic" <amachanic@.hotmail._removetoemail_.com> wrote in message
news:ekLNvJE5EHA.2804@.TK2MSFTNGP15.phx.gbl...
> Confirmed:
> Microsoft SQL Server 2000 - 8.00.760 (Intel X86) Dec 17 2002 14:22:05
> Copyright (c) 1988-2003 Microsoft Corporation Standard Edition on Windows
> NT 5.0 (Build 2195: Service Pack 4)
>
> |--Compute
>
Scalar(DEFINE:([Customers].[CompanyNameNoSpace]=replace([Customers].[Company
> Name], Convert(space(1)), Convert(''))))
> |--Bookmark Lookup(BOOKMARK:([Bmk1000]),
> OBJECT:([Northwind].[dbo].[Customers]))
> |--Index
>
Seek(OBJECT:([Northwind].[dbo].[Customers].[IX_Customers_CompanyNameNoSpace]
> ), SEEK:([Customers].[CompanyNameNoSpace]=Convert([@.1])) ORDERED FORWARD)
> :-)
>|||Indeed. I hadn't noticed.
I think Microsoft never took the time to build that optimization. To me,
that shows that they really only added a rudimentary version of indexed
computed columns.
Because the index value could have been used. If you change the query to
SELECT CustomerID,CompanyNameNoSpace FROM Customers WHERE
CompanyNameNoSpace='EasternConnection'
you will see that only the covering index is accessed, and that the
computed value is not recomputed.
Gert-Jan
Adam Machanic wrote:
> Actually, I just took a closer look at the execution plan. Interesting that
> CompanyNameNoSpace is being re-computed after the bookmark lookup, even
> though it was used for the initial index seek! I'm surprised that SQL
> Server can't use the value from the index...
> --
> Adam Machanic
> SQL Server MVP
> http://www.sqljunkies.com/weblog/amachanic
> --
> "Adam Machanic" <amachanic@.hotmail._removetoemail_.com> wrote in message
> news:ekLNvJE5EHA.2804@.TK2MSFTNGP15.phx.gbl...
> > Confirmed:
> >
> > Microsoft SQL Server 2000 - 8.00.760 (Intel X86) Dec 17 2002 14:22:05
> > Copyright (c) 1988-2003 Microsoft Corporation Standard Edition on Windows
> > NT 5.0 (Build 2195: Service Pack 4)
> >
> >
> > |--Compute
> >
> Scalar(DEFINE:([Customers].[CompanyNameNoSpace]=replace([Customers].[Company
> > Name], Convert(space(1)), Convert(''))))
> > |--Bookmark Lookup(BOOKMARK:([Bmk1000]),
> > OBJECT:([Northwind].[dbo].[Customers]))
> > |--Index
> >
> Seek(OBJECT:([Northwind].[dbo].[Customers].[IX_Customers_CompanyNameNoSpace]
> > ), SEEK:([Customers].[CompanyNameNoSpace]=Convert([@.1])) ORDERED FORWARD)
> >
> > :-)
> >|||On Wed, 15 Dec 2004 07:35:02 -0800, "Neil Hambly"
<hambly_neil@.hotmail.com> wrote:
>Does anyone have any ideas on recoding or indexes changes to help here
If you have a LOT of this kind of thing, how about using the full-text
indexing?
J.

Index Speed use of REPLACE in clause

[Customers].[CompanyNameNoSpace]=replace([Customers].[Company
Name], Convert(space(1)), Convert(''))))
|--Bookmark Lookup(BOOKMARK

[Bmk1000]),
OBJECT

[Northwind].[dbo].[Customers]))
|--Index
Seek(OBJECT

[Northwind].[dbo].[Customers].[IX_Customers_CompanyNameNoSpace]
), SEEK

[Customers].[CompanyNameNoSpace]=Convert([@.1])) ORDERED FORWARD)
:-)
Adam Machanic
SQL Server MVP
http://www.sqljunkies.com/weblog/amachanic
"Gert-Jan Strik" <sorry@.toomuchspamalready.nl> wrote in message
news:41C2E4BC.868B93CB@.toomuchspamalready.nl...[vbcol=seagreen]
> I could be wrong. I thought that maybe indexes on computed columns would
> not be automatically used in Standard Edition, just as indexes on views
> are not automatically used (unless you use Enterprise Edition or provide
> special hints).
> But as I said: I could be wrong. Maybe someone with Standard Edition can
> test this example to see if an index seek is used.
> USE Northwind
> GO
> ALTER TABLE Customers ADD CompanyNameNoSpace AS
> Replace(CompanyName,space(1),'')
> GO
> CREATE INDEX IX_Customers_CompanyNameNoSpace ON
> Customers(CompanyNameNoSpace)
> GO
> SET SHOWPLAN_TEXT ON
> GO
> SELECT * FROM Customers WHERE CompanyNameNoSpace='EasternConnection'
> GO
> SET SHOWPLAN_TEXT OFF
> Gert-Jan
> Adam Machanic wrote:
|||Thanks,
Gert-Jan
Adam Machanic wrote:[vbcol=seagreen]
> Confirmed:
> Microsoft SQL Server 2000 - 8.00.760 (Intel X86) Dec 17 2002 14:22:05
> Copyright (c) 1988-2003 Microsoft Corporation Standard Edition on Windows
> NT 5.0 (Build 2195: Service Pack 4)
> |--Compute
> Scalar(DEFINE

[Customers].[CompanyNameNoSpace]=replace([Customers].[Company
> Name], Convert(space(1)), Convert(''))))
> |--Bookmark Lookup(BOOKMARK

[Bmk1000]),
> OBJECT

[Northwind].[dbo].[Customers]))
> |--Index
> Seek(OBJECT

[Northwind].[dbo].[Customers].[IX_Customers_CompanyNameNoSpace]
> ), SEEK

[Customers].[CompanyNameNoSpace]=Convert([@.1])) ORDERED FORWARD)
> :-)
> --
> Adam Machanic
> SQL Server MVP
> http://www.sqljunkies.com/weblog/amachanic
> --
> "Gert-Jan Strik" <sorry@.toomuchspamalready.nl> wrote in message
> news:41C2E4BC.868B93CB@.toomuchspamalready.nl...

Friday, March 9, 2012

index for tables that located in different databases?

When design index for table to speed the joining, where conditions, etc,
any different comparing with tables in the same database in the same server?
and how about the tables in different server?No difference. In the end, SQL Server need to access the data. If that access ban be supported by an
index (to limit number of rows to go though, support sort or grouping etc), then it doesn't make a
difference from there the whole query originated.
--
Tibor Karaszi, SQL Server MVP
http://www.karaszi.com/sqlserver/default.asp
http://www.solidqualitylearning.com/
Blog: http://solidqualitylearning.com/blogs/tibor/
"nick" <nick@.discussions.microsoft.com> wrote in message
news:BBA362DF-462E-494C-95A3-2B8A61D60A94@.microsoft.com...
> When design index for table to speed the joining, where conditions, etc,
> any different comparing with tables in the same database in the same server?
> and how about the tables in different server?

index for tables that located in different databases?

When design index for table to speed the joining, where conditions, etc,
any different comparing with tables in the same database in the same server?
and how about the tables in different server?
No difference. In the end, SQL Server need to access the data. If that access ban be supported by an
index (to limit number of rows to go though, support sort or grouping etc), then it doesn't make a
difference from there the whole query originated.
Tibor Karaszi, SQL Server MVP
http://www.karaszi.com/sqlserver/default.asp
http://www.solidqualitylearning.com/
Blog: http://solidqualitylearning.com/blogs/tibor/
"nick" <nick@.discussions.microsoft.com> wrote in message
news:BBA362DF-462E-494C-95A3-2B8A61D60A94@.microsoft.com...
> When design index for table to speed the joining, where conditions, etc,
> any different comparing with tables in the same database in the same server?
> and how about the tables in different server?

index for tables that located in different databases?

When design index for table to speed the joining, where conditions, etc,
any different comparing with tables in the same database in the same server?
and how about the tables in different server?No difference. In the end, SQL Server need to access the data. If that acces
s ban be supported by an
index (to limit number of rows to go though, support sort or grouping etc),
then it doesn't make a
difference from there the whole query originated.
Tibor Karaszi, SQL Server MVP
http://www.karaszi.com/sqlserver/default.asp
http://www.solidqualitylearning.com/
Blog: http://solidqualitylearning.com/blogs/tibor/
"nick" <nick@.discussions.microsoft.com> wrote in message
news:BBA362DF-462E-494C-95A3-2B8A61D60A94@.microsoft.com...
> When design index for table to speed the joining, where conditions, etc,
> any different comparing with tables in the same database in the same serve
r?
> and how about the tables in different server?

Wednesday, March 7, 2012

Index Design Question

I want to create an index that will cause the cost of the query to be as low as possible and also
must minimize the space that is used by the index. What type of index/parameters I can associate when I create an Index. I already have a clustered index

Only option will be non clustered index becuase you have already one clustered index...

You can't minimize the space used by the index, it is depends on columns used to create index...

but you can minimize the space used for index creation using SORT_TEMPDB option.

|||my query is like this
select productid,
sum(qty) as totalQTY,
count(*) as total
from table1
where desqty=2
group by productid

I have clusted index already defined in the id which is the identity

I have 2 options create non clustered on desqty and include product id as the included column
second is non clustered desqty and inculde both the productid and qty as included column

which one will be the better option?|||

Try both options and study the execution plans to find out for yourself.

You should find the second option to be the most performant as the index would be a 'covering index' and the base table would not need to be touched when the data is read.

Chris

|||

Turn on statistics IO by running the statement SET STATISTICS IO ON

Then, try running the query with the graphical execution plan turned on, and study the io statistics results.

I would try to create a "covering" index by creating an index that has desqty, productid, and qty (in that order) as regular index columns rather than included columns.

|||

Admin, there are some new features in SQL 2005.. whre you can name other columns in an index, and that will help make covered indexes so SQL Server might not need to query as many pages... see teh INCLUDE parameter of a CREATE INDEX...

Also, there are some new system views... that can help isolate missing stats/indexes...

select * from sys.dm_db_missing_index_details

select * from sys.dm_db_missing_index_groups

select * from sys.dm_db_missing_index_group_stats

A sample of how to join them follows...

SELECT mig.*, statement AS table_name,

column_id, column_name, column_usage

FROM sys.dm_db_missing_index_details AS mid

CROSS APPLY sys.dm_db_missing_index_columns (mid.index_handle)

INNER JOIN sys.dm_db_missing_index_groups AS mig ON mig.index_handle = mid.index_handle

ORDER BY mig.index_group_handle, mig.index_handle, column_id;

Bruce

Index Design Question

Only option will be non clustered index becuase you have already one clustered index...

You can't minimize the space used by the index, it is depends on columns used to create index...

but you can minimize the space used for index creation using SORT_TEMPDB option.

|||my query is like this
select productid,
sum(qty) as totalQTY,
count(*) as total
from table1
where desqty=2
group by productid

I have clusted index already defined in the id which is the identity

I have 2 options create non clustered on desqty and include product id as the included column
second is non clustered desqty and inculde both the productid and qty as included column

which one will be the better option?|||

Try both options and study the execution plans to find out for yourself.

You should find the second option to be the most performant as the index would be a 'covering index' and the base table would not need to be touched when the data is read.

Chris

|||

Turn on statistics IO by running the statement SET STATISTICS IO ON

Then, try running the query with the graphical execution plan turned on, and study the io statistics results.

I would try to create a "covering" index by creating an index that has desqty, productid, and qty (in that order) as regular index columns rather than included columns.

|||

Also, there are some new system views... that can help isolate missing stats/indexes...

select * from sys.dm_db_missing_index_details

select * from sys.dm_db_missing_index_groups

select * from sys.dm_db_missing_index_group_stats

A sample of how to join them follows...

SELECT mig.*, statement AS table_name,

column_id, column_name, column_usage

FROM sys.dm_db_missing_index_details AS mid

CROSS APPLY sys.dm_db_missing_index_columns (mid.index_handle)

INNER JOIN sys.dm_db_missing_index_groups AS mig ON mig.index_handle = mid.index_handle

ORDER BY mig.index_group_handle, mig.index_handle, column_id;

Bruce

Sunday, February 19, 2012

Index aginst table having lot of inserts

Hi ,
i have a question reg index on my table which is having somany inserts. is
that good design to have index on table table which has lot of inserts?
Thanks
BhaskarLike many design considerations, it depends. Virtually all tables should
have a primary key and corresponding index. Additional indexes are often
appropriate to speed up query performance. Of course, the benefits of these
indexes need to be weighted against the associated costs of slower inserts
and space requirements. Since data is usually read more times than written,
the improved data retrieval performance often justifies the write
performance penalty. Storage is inexpensive nowadays.
Hope this helps.
Dan Guzman
SQL Server MVP
"Bhaskar" <Bhaskar@.discussions.microsoft.com> wrote in message
news:D91C16BA-D172-4929-81AB-E92C17F0F8FE@.microsoft.com...
> Hi ,
> i have a question reg index on my table which is having somany inserts. is
> that good design to have index on table table which has lot of inserts?
> Thanks
> Bhaskar|||When you say that the table has a lot of inserts, are you speaking of
transactional inserts or bulk inserting?
http://www.microsoft.com/technet/pr...br />
4fec.asp
If you are concerned about fragmentation of indexes as a result of inserts:
http://www.microsoft.com/technet/pr...n/ss2kidbp.mspx
"Bhaskar" <Bhaskar@.discussions.microsoft.com> wrote in message
news:D91C16BA-D172-4929-81AB-E92C17F0F8FE@.microsoft.com...
> Hi ,
> i have a question reg index on my table which is having somany inserts. is
> that good design to have index on table table which has lot of inserts?
> Thanks
> Bhaskar

Friday, March 30, 2012

Index Speed use of REPLACE in clause

Index Speed use of REPLACE in clause

Friday, March 9, 2012

index for tables that located in different databases?

index for tables that located in different databases?

index for tables that located in different databases?

Wednesday, March 7, 2012

Index Design Question

Index Design Question

Sunday, February 19, 2012

Index aginst table having lot of inserts

index and key

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