When working with databases containing myriad of huge tables, I am very much tempted to create categorized views on those tables in order to simplify and facilitate data query programming? Some developers I talk to say such views generally slow down query performance. Is this true?
Thanks.
Over the years I've read and experienced where joining more then 5 tables can lead to performance problems. This number can vary based upon the amount of data in each table, if and how indexes are used and the complexity of the query, but 5 has always been a good rule of thumb. Unfortunately I do not know what rule to apply in regards to joing views.
A developer has experienced timeout problems periodically when opening a view in EM or when running the code which makes-up the view. I decided to look at the view and noticed it references tables and views, which reference more views, which in turn reference other views. In all the initial view references 5 tables and 8 views directly and indirectly, with some of the views containing function calls. What are your thoughts on how many views and tables are too many when it comes to joins and query performance.
Thanks, Dave
I have a table with about 20,000 records. So, to minimise performance issues, i try to only retrieve the top 100 records. The databaset retrieved can be paged and sorted. Below is my code, but it's taking quite a while even to only load the 100 records. Any suggestions?Private Sub BindGrid() Dim connectionString As String = "MyConnectionString" Dim dbConnection As System.Data.IDbConnection = New System.Data.SqlClient.SqlConnection(connectionString)
Dim queryString As String = "SELECT TOP 100 [Person].* FROM [Person] ORDER BY " & viewstate("sortField").ToString() & " " & viewstate("sortDirection").ToString()
Dim dbCommand As System.Data.IDbCommand = New System.Data.SqlClient.SqlCommand dbCommand.CommandText = queryString dbCommand.Connection = dbConnection
Dim dataAdapter As System.Data.IDbDataAdapter = New System.Data.SqlClient.SqlDataAdapter dataAdapter.SelectCommand = dbCommand Dim dataSet As System.Data.DataSet = New System.Data.DataSet dataAdapter.Fill(dataSet)
Try DataGrid1.DataSource = dataSet DataGrid1.Databind() Catch e As Exception DataGrid1.CurrentPageIndex = 0 End TryEnd Sub
Hi,Can't post specifics at the moment but if this seems like a commonproblem any help would be appreciated.When querying with ~6 tables, using mostly left outer joins, I getstandard performance with the where clausewhere XXX is not nullhowever, if I try the clausewhere XXX = 4the query takes upwards of 5-6 minutes (I just stop it running at thatpoint.The field XXX is in the 'main' table (to which the joins attach), it'san integer field too so I can't see too many problems there.There's no index on the XXX field, but if I remove the joins, I getstandard performance doing either query.So why would the second query's performance differ so significantly?Cheers,Chris
View 3 Replies View RelatedI have a stored procedure that queries a database using a Selectstatement with some inner joins and conditions. With over 9 millionrecords it takes 1 min 36 sec to complete. This is too slow for myrequirements.Is there any way I can optimize this query. I have thought aboutusing an indexed view. I haven't done one before, does anyone know ifthis would have potential to improve performance or indeed any otherperformance enhancing techniques I might try.SELECT vehicle.vehicle_idFROM (( [vehicle]INNER JOIN [vehicle_subj_item_assn] onvehicle.vehicle_id=[vehicle_subj_item_assn].vehicle_id)INNER JOIN [subj_item] on[vehicle_subj_item_assn].subj_item_id=[subj_item].subj_item_id)INNER JOIN [template_field] on[subj_item].subj_item_id=[template_field].subj_attr_idWHERE([template_field].template_field_id=@template_field_id) AND([template_field].template_field_type_id=3) AND([vehicle_subj_item_assn].subj_item_value_text=@value) AND(vehicle.end_dtm IS NOT NULL)ThanksGavin
View 3 Replies View RelatedHi,
I have come across this problem with SQL server both on 2000 and 2005. I am stating an example here.
I have two partitioned tables and a view on top of both tables as below:
create table [dbo].[Table_1]
(
[TableID] INTEGER PRIMARY KEY NONCLUSTERED
CHECK NOT FOR REPLICATION ([TableID] BETWEEN 1 AND 999),
[AnyOtherColumn] int NOT NULL ,
) ON [Primary]
GO
create table [dbo].[Table_2]
(
[TableID] INTEGER PRIMARY KEY NONCLUSTERED
CHECK NOT FOR REPLICATION ([TableID] BETWEEN 1000 AND 1999),
[AnyOtherColumn] int NOT NULL ,
) ON [Primary]
GO
create view TableView
as
select * from Table_1
union all
select * from Table_2
GO
Note the NOT FOR REPLICATION clause on the check constraint on the TableID column.
I then ran the query execution plan for the following query on both SQL server 2000 and 2005.
select * from TableView where TableID = 10
On both the versions the execution plan shows and Index seek on both the tables in the view. This means that my partitioning is not working. If I remove the primary key constraint from the TableID column, the same query on the view shows a table scan on all the underlying tables. This is even worse.
Next, create the same tables and views again, now without the NOT FOR REPLICATION clause on the check constraint as show below:
create table [dbo].[Table_1]
(
[TableID] INTEGER PRIMARY KEY NONCLUSTERED
CHECK ([TableID] BETWEEN 1 AND 999),
[AnyOtherColumn] int NOT NULL ,
) ON [Primary]
GO
create table [dbo].[Table_2]
(
[TableID] INTEGER PRIMARY KEY NONCLUSTERED
CHECK ([TableID] BETWEEN 1000 AND 1999),
[AnyOtherColumn] int NOT NULL ,
) ON [Primary]
GO
create view TableView
as
select * from Table_1
union all
select * from Table_2
GO
Now run the query execution plan for the same query again.
select * from TableView where TableID = 10
This time you would see that it does an index scan only on the first parititon table. This time it proves that the partitioning works.
I would like to know why does the NOT FOR REPLICATION clause in the check constraint make such a huge difference?
Is it a bug in SQL server?
Or am I missing any thing?
Any help appreciated.
Thanks
In my database/MY SERVER (SQL7/Win2K), I run a simple query with a Table/10000 rows (without cluster index):
SELECT * FROM TABLE
it take over 30s. Why it's slow? How can I check for reason? How to configure my server to improve performance?
Thanks in advance.
TH
----------------------------------
SP_CONFIGURE's RESULT in MY SERVER
----------------------------------
Table 'spt_values'. Scan count 1, logical reads 2, physical reads 0, read-ahead reads 0.
name minimum maximum config_value run_value
----------------------------------- ----------- ----------- ------------ -----------
affinity mask 0 2147483647 0 0
allow updates 0 1 1 1
cost threshold for parallelism 0 32767 5 5
cursor threshold -1 2147483647 -1 -1
default language 0 9999 0 0
default sortorder id 0 255 52 52
extended memory size (MB) 0 2147483647 0 0
fill factor (%) 0 100 0 0
index create memory (KB) 704 1600000 0 0
language in cache 3 100 3 3
language neutral full-text 0 1 0 0
lightweight pooling 0 1 0 0
locks 5000 2147483647 0 0
max async IO 1 255 32 32
max degree of parallelism 0 32 0 0
max server memory (MB) 4 2147483647 2147483647 2147483647
max text repl size (B) 0 2147483647 65536 65536
max worker threads 10 1024 255 255
media retention 0 365 0 0
min memory per query (KB) 512 2147483647 1024 1024
min server memory (MB) 0 2147483647 0 0
nested triggers 0 1 1 1
network packet size (B) 512 65535 4096 4096
open objects 0 2147483647 0 0
priority boost 0 1 1 1
query governor cost limit 0 2147483647 0 0
query wait (s) -1 2147483647 -1 -1
recovery interval (min) 0 32767 0 0
remote access 0 1 1 1
remote login timeout (s) 0 2147483647 5 5
remote proc trans 0 1 0 0
remote query timeout (s) 0 2147483647 0 0
resource timeout (s) 5 2147483647 10 10
scan for startup procs 0 1 0 0
set working set size 0 1 0 0
show advanced options 0 1 1 1
spin counter 1 2147483647 10000 10000
time slice (ms) 50 1000 100 100
two digit year cutoff 1753 9999 2049 2049
Unicode comparison style 0 2147483647 196609 196609
Unicode locale id 0 2147483647 1033 1033
user connections 0 32767 0 0
user options 0 4095 0 0
Table 'spt_values'. Scan count 43, logical reads 108, physical reads 0, read-ahead reads 0.
Table 'sysconfigures'. Scan count 1, logical reads 2, physical reads 0, read-ahead reads 2.
I am having performance issues on a SQL query in Access. My query isaccessing and joining several tables (one very large one). The tables arelinked ODBC. The client submits the query to the server, separated byseveral states. It appears the query is retrieving gigs of data from thetable and processing the joins on the client. Is there away to perform moreof the work on the server there by minimizing the amount of extraneous tabledata moving across the network and improving performance (woefully slowabout 6 hours)?
View 3 Replies View RelatedHello,
From what I have read from various sources, views as an Oledb Source component source are very slow. In practice I have experienced this as well - they are painfully slow. One of the most recent books out on SSIS documents this fact and says to use an ad hoc query instead.
I'm curious if someone from Microsoft could expxlain why this is in more detail. I have clients ask this question, and would like to know for my own purposes as well. Further it would be nice to know if this is expected to change in v.next.
Thanks much
I'm currently using a system where the number of column in any given table is so great that the columns are often split into additonal tables. I know it's a wierd design but there you go. So I have to deal with tables looking like: MathResult, MathResult_2, MathResult_3, etcEach table is basically the same entity, i.e. it has the same number of rows and each row has the same key value as its peer tables. My question is that should I create a view to bring the tables together, given that a View doesn't seem to have any sort of row-size restriction? Normally I shy away from Views because I've always found them to bring performance down. Any thoughts?
View 4 Replies View RelatedHello everyone,
I want to use VIEWS to filter records using a stored procedure to call the VIEW. Will I get a performance boost from using a VIEW, or should I just use the SQL statement that I used to create the VIEW, in my SP and forget about calling a VIEW at all?
Thanks,
Nathan
Hi all...
I need urgent help, about someting:
i've developed and deploy an aspnet web site (data works with sqlserver), but after a few minutes working with some users, the permormance slows and stop the site.
please help me what should i do......
I need to transfer a database from one server to another, I'm using the DTS utility because the servers have different sort orders. our database size is about 5GB which include about 2500 tables. Using DTS is taking many hours to transfer all objects and data. is there a better/faster way to do this?
Any help would be appreciated, Thank you
Help! I am new to SQL (6.5) and am designing a small database on a small LAN.
Everything seems to work fine until more than one user gets in the database.
It was originally an Access database and we upsized some of the information to SQL.
I have not upsized all the tables yet, and am not sure if that is causing a problem.
Since we are new to SQL we are trying to make all the changes in Access then upsize
everything. If this is the problem though, I will not be hesitant in upsizing.
Any ideas?
Since sp2 a number of applications, specifically web ado access has slowed very badly and I seem to be seeing a high cpu usage too. Internal jobs such as backups and table defrags are not affected. I'm on a 4 way box with ample hardware .. stats indexes etc. are fine .. client access is just slow. I suspect mdac but I can't pin anything down and it's driving me crazy !!!!!
I've even built a new box with a fresh install but to no avail.
help ???
I'm running the following statements. They have been running for 48 hours and counting... In performance monitor, I can see the system is steadily 100% disc bound. Any idea how to get status or ETA on these? Any idea how I can speed up such actions? This seems unusually slow. There are no errors in the Error Log. Does other DBMS systems (such as Oracle) handle such scenarios more quickly or with better status information?
INSERT INTO Domains (Domain)
SELECT DISTINCT Domain FROM Stages WHERE Domain NOT IN (SELECT Domain FROM Domains)
UPDATE Stages SET DomainID = (SELECT Domains.[ID] FROM Domains WHERE Domains.Domain = Stages.Domain)
Stages is 173 million records
Domains is 2.4 million records
This is running on pretty decent hardware:
Windows 2000 SP5
SQL Server 2000 Enterprise Edition SP3a
Dual 3.06 GHz Xeons with HyperThreading enabled (4 virtual CPUs)
4GB RAM (OS 3GB switch is enabled to give SQL Server 3GB of RAM)
70GB SCSI boot drive
Data/Transaction Log is on a RAID 5, 30 spindle, fibrechannel SAN
Hi - I have MS SBA2007beta and Office Outlook 2007 BCM Beta. Both use SQL2005 and they are both as slow to point of being frustrating. Outlook2007 without BCM is fine and every other application runs fine if no SQL server apps are present.
I have this running on a 2.8ghz desktop with 1G memory and a Laptop of 1.8ghz and 1.5g memory. The laptop is far faster.
When SQL apps are running everything is slowed.
I have a query which retrieves data from 4-5 tables. To restrict the acess directly to the tables, views have been created on all these tables. These views are just select * from the tables. Two of these 5 tables have 700 Million and 8 Million rows respectively. And all the tables are having indexes. My issue here is that my query on views take three times more then the duration it takes to retrive data directly from tables. e.g. To retrieve 1 Miliion rows, it takes just 7-10 minutes on tables but on views it takes more than 30 minutes. When I check the query plan for both the options, I can see that indexes are being picked up but still the views are very slow.
Creating indexes on views is not feasible option for me as it requires DDL changes and so much testing efforts.
Hi guys,
I'm have a table which is filled daily by a procedure. This procedure executes for around 2 hours.
Now i also want to create a clustered index view on this table.
Now during the time data is being inserted in this table, would the performance of server get hit.?
Since it think it would continiously be updating this view during this duration.
Is there a way i can temporarily disconnect the view?
Please advice.
Thanks.
Hello,
I have the same database on two different servers. One for production and one for testing. A view that I use runs in less than 2 seconds on the test system, but takes almost 2 minutes on the production server.
What I have noticed is on the test server the view will use an index. The production server ends up scanning a whole table. All indices are the same on both machines for the tables involved and I have updated the statistics. I even went through the process of creating a new table with its indices for the table that is being scanned. Both machines have had service pack 1 installed on them.
Any ideas?
An Application Times out with tons of SQL Server Locks but there is no log of any errors in SQL Servers. I checked all the Indexes and I reindex it but still same issues. CPU is 100% full at that time and users unable to do anything. Any ideas on how to fix it
View 1 Replies View RelatedHi
We are facing performance related problem using Sql server 2000.
We have one stand alone P4 Pc (128 ram) and around 30 users access the sql server through network.
We have written our aplication in VB 6 and backend as Sql Server 2000. We have used Stored Procedure where ever necessary. We have used cursor location as Server side.
When we start with 5 users it is not slow, when all the users say 30 comes in it is slow down.
Can some one help to find out what is the problem.
Thanks
I'm still new to SQL Server so some of my lingo/verbage may be incorrect, please bare with me.
The company I work for relies strictly on ASP and SQL Server for 85% of it's daily operations. We have some Access projects and some VB projects as well, but for the majority it's ASP and SQL Server.
Previously we had 2 T1 lines with something like 3MB a piece and a handfull of Dell Servers. Our main server is also a Dell running Windows Server 2003 and is hosted through a reputable company here in town. They have a host of fiber lines running all over so I know we're getting good throughput. We've actually just upgradded to a DS3 but we're still working out the kinks with that. Anyway, I just want to eliminate that up front - we have great connection speeds.
The problems lies, I believe in our database design. The company supposedly had a DBA come in and help setup the design some 3 or 4 years ago, however even with my limited knowledge I feel like something is just not working right.
Our main table is "Invoices" which is obviously all of our Invoices, ever. This table has an Identity field "JobID" which is also the Clustered Index. We have other Indexes as well, but it appears they're just scattered about. The table probably 30-40 fields per row and ONLY 740,000 rows. Tiny in comparison to what I'm told SQL Server can handle.
However, our performance is embarassing. We've just landed a new client who's going to be brining us big business and they're already complaining about the speed of their website. I am just trying to figure out ways to speed things up. SQL is on a dedicated machine I believe with dual Xeon processors and a couple gigs of ram. So that should be ok. THe invoices table I spoke of is constantly accessed by all kinds of operations as it's heart of what we do. We also have other tables such which are joined on this table to make up the reporting we do for clients.
So I guess my question is this. Should the Clustered Index be the identify field and is that causing us problems? We use this field alot for access a single Invoice at a time and from what I understand this makes it a good Clustered Index, because the index IS the jobID we're looking for. But when it comes time to do reporting for a client, we're not looking at this field. We just pull the records for that Clients Number. And we only have 1400 clients at this point. So if we were to make the "ClientID" field the Clustered Index, it would much faster to Zero in on the group of Invoices we wanted because the ClientID is ALWAYS included in our queries.
But because a "DBA" came in to design this setup, everyone is afraid to change it. I guess it's hard to explain without people sitting here going through the code and look at the structures of all our tables - but I guess what I need is like a guide of what to do to easily increase performance on SQL Server and the proper use of Clustered and Non-Clustered Indexs and how to mix and match those.
Sorry I wrote a book.
Ideas? This place has always helped me before, so thanks in advance!
Hi,
I'm executing a stored procedure in my local LAN which executes another one in a loop and I update a Table. The number of loops is about 6300.
This operation takes about 25 seconds in my local LAN.
Then I try to execute though in a VPN which has an upload speed of 256 kbps. I open query analyser connect to the remote server which is must faster than mine and I just write exec mystoredprocname in order to execute the procedure. The performance is very very slow.
In 7 minutes 180 loops are completed out or 6300.
I really cannot understand this. What is the reason of such slow perfomance?? My ADSL model displays no activity when the procedure is executed. I just use the PRINT method in MSSQL in order to display the progress of the operation. I tried to comment it out but with no difference.
I also use SET NOCOUNT ON in order not to display the update results.
Can someone explain me the cause for this? Are there some tricks in order to improve the performance when a slow connection is used like a ADSL with a static IP? It seems that something wrong is happening here.
Best Regards,
Manolis Perrakis
dear friends,
i have dropped many objects and recreated in a database.suddenly my database became very slow. so please any one of friends give solution.
I have a bunch of packages that take views and create tables from them. Some of the views are rather complex, but the packages themselves are very simple... drop and re-create a table using the data from a view on the same server. We create a new DB for each year, and this year we've upgraded to a new server with SQL 2005, so our DTS packages on the 2000 SQL server had to be recreated in SSIS on the new server. No problem, as I said the packages are really simple. But when I create the packages in SSIS they now take an extremely long time to execute, and I cannot figure out why.
For instance, one DTS package would take approximately 5 minutes to run when the view contained hundreds of thousands of rows and the underlying tables contained millions. But now, even with MUCH smaller tables (since it's the beginning of the year, new DB) the SSIS package I created on the new server takes over an hour, literally. The view that the SSIS package is using to create the table only takes about 15 seconds to execute in management studio (only about 16,000 rows). How can this possibly take so long??
the new server is virtually the same hardware-wise... 4 x 2400mhz, 4gb ram, win2k3 server
I have a stored procedure that has some problems with slow performance.The procedure has 2 parameters@firstnamevarchar(100)@lastnamevarchar(100)These parameters can have values like a%, that is wildcard searches.The strange thing is that if one of the parameters has the value %, andthe other one a%, the performance is very bad.If i subsistute the variables with exactly the same values hardcoded inthe where-clause, the query is very fast.If both variables has some characters prepending the percent sign, theperformance is better.SELECT distinct u.user_id, u.username, u.status_idFROM statusnames sn, statuses s, users u, users_persons up, persons p,users_roles urWHERE p.lastname like @lastnameAND p.firstname like @firstnameAND s.status_id = u.status_idAND sn.statusname_id = s.statusname_idAND u.user_id = up.user_idAND up.person_id = p.person_idWhat makes SQL server behave so differently with variables andhardcoded values?
View 6 Replies View RelatedHi,We have shifted one of our data processing to a new instance of SQL2005. For this a new DB was created in SQL2005 and it is not anupgrade of SQL200 DB.The data processing application is a VB6 application that runs a batchprocess to insert about4.5 million records everyday in this SQL 2005 database. I am usingADO(ver 2.6) Connection object to execute T-SQL insert statements toinsert the 4.5 mill. records.This same application used to insert the data in the SQL 2000databaseand used to take about 2.5 hours to do so. After moving it to SQL2005 the performance has really detriorated and it now takes morethan6 hours.Is there any configuration change that I need to do in SQL 2005?Please help.Note: There is also an instance of SQL 2000 running in the sameserver.TIA,Tawfiq
View 3 Replies View RelatedI was transfering more that 100,000 records from flat file to sql table
It took about 1 hour.Is this the way it is?????i used oledb command.
As the data passes by i got to insert to several table.Like i insert some of incoming data to one table then get the key from that table and insert rest of the data with the key field from previous table to another table.
In this case i felt OLedb would be best as we can use query.
I cannot use oledb destination as it has only error output(to insert some of incoming data and i want to have a look up to get the key but oledb des has only error output)
i cannot use sql destination as the database is sql server 2000.It dosent let me.
How can i increase the performance????Please let me know
Hello all!
View 1 Replies View RelatedHi.
I have successful upgraded from Windows 2000 / SQL Server 2000 to Windows 2003 / SQL Server 2005. Here is the process:
- Install Windows 2003 / SQL Server 2005 on new VM instance
- Detached SQL Server 2000 database -> Copy data to the new server and Attached to SQL Server 2005
- Run scripts to restore user login
- Change Compatibility level to: SQL Server 2005 (90)
Now, open 3rd party application and connect to the new database server (via IP address), the application was connecting ok and access data without no problem. However, database take more than 5 minute to connect/open instead of 30sec via the old the server?
Please adivse what could be the issue? Thanks!
OK so I have this EAV system on a server that is old enough for kindergarten. Insanely enough, this company that makes more money than any of your gods can not buy me a new box.
Before you say "redesign", I need funding allocated for that. See my first statement.
Anywho, I have this page that touches the dreaded Value table and does a clustered index seek on it. Can't search faster than that, right? Well I am getting some funding for "performance tuning". I am wondering if maybe incorporating some clustered index views involving the value table and producing a smaller clustered index for it to seek may alleviate some of this. Any thoughts?
Dear All,
i've tried with indexed views, but because the view is referenceing another view, i was unable to create a clustered index on that view.
so please let me know how can i improve the performance of the view.
thank you very much
Vinod
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