SELECT INTO..# Performance Impact In SQL 7.0
Jan 18, 2001
I want to determine the performance impact caused by the extensive use of the 'select into #' statement in a production environment. The current situation is that our reports team extensively uses the 'select into #' statement to build smaller subsets of data. These subsets are then used as the basis to create summary style reports and exports. All this is accomplished via the use of SQL pass-through.
After these reports/exports are completed and tested, they are then released to our operations department and the users. The reports/exports then can be run against the production server at the discretion of the user, provided they have the appropriate permissions. These reports/exports target the live data on the primary production server that already has been designated for the use of the application software.
Now I know that reporting against a transactional-based server, where the users run the application, is not a very good idea. (Inherited) I am currently migrating all reports/exports to a reporting server. Although it will still be transaction-based, the reports/exports will be isolated from user activity. Eventually we will be moving toward a warehouse scenario.
I also know that the extensive use of the 'select into #' statement is not a coding practice for use in production. I provided several alternatives to this practice
1) insert..select 2) insert..execute - from stored procedure
I have read that in the in sql 6.5 that this may cause severe performance and locking behaviors in system db's and tempdb. However, in the following document on the Microsoft Knowledge Base, it indicates that SQL 7.0 may have corrected this issue.
Q153441 - FIX SELECT INTO Locking Behavior.htm
Despite the indication of being corrected, I am still not convinced. I am frequently seeing drastic performance hits, especially when several of the reports are running. (which is very common) My concern is that moving these reports/exports to a reporting server may save the users; I believe that it may be migrating the problem to another location. I will be working with the developers to optimize their code and will investigate index issues.
** To make a long story short. I would like someone who has experience with this provide me with the top 5+ reasons not to use the 'select into #' methodology in a production environment. Further, if anyone has any documentation, I would surely like the info.
Thanks, Dave
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Feb 19, 2004
Hi,
Anybody have any idea howmuch % of performance will be affect if we are using varchar instead of char data type?.
Thanks,
Ravi
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Apr 18, 2008
I have been collecting information about 20 performance counters (memory, IO, cpu, SQL) that refresh every 15 seconds, would that have any performance hit in the server? what are best practices when collecting information via performance counters?
Thanks
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Jan 15, 2008
I want to use "on delete cascade" in one of my tables but I'm worried though whether this can affect the performance when having millions of records. To explain more I'm working on a social networking website and I have two tables UserAccounts, in which I only keep the username and password and a few related fields, and Profiles in which I keep the profile data for users, I want to be sure that I won't have any records in the Profiles table without corresponding records in the UserAccounts table. Please see the DDL below to understand more the structure of the tables:
CREATE TABLE UserAccounts
(
UserID INT NOT NULL IDENTITY(1,1) PRIMARY KEY,
UserName VARCHAR(20) NOT NULL,
Password VARCHAR(20) NOT NULL,
--other fields (e.g. last login .. etc)
)
CREATE TABLE Profiles
(
UserID INT NOT NULL REFERENCES UserAccount(UserID),
-- other fields (e.g. birthdate, nationality .. etc)
)
Any suggestions are highly appreciated...
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Jun 21, 2007
Hello All,
When creating my database I have modeled some of the tables after the Adventureworks sample database.
There are some fields or entire tables in Adventureworks that I do not see an imediate use for, however; I would hate to ommit them to find out later they would have been benificial. (.eg territory table).
In general terms what would the impact be on size and performance of a database which contains tables or fields that do not contain data.
Thanks for your help!
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Jul 27, 2015
For example in a Select Statement we have many tables and we have Where Clause with many conditions with AND operations. Do the SQL SERVER would apply the Where clause after all fetch or can dynamically decide about to include the related Tables from Select Statement Orderly with respect to where clause predicates? (SQL SERVER would not fetch data of those tables for its Select, where the AND condition in Where clause fails or by logic would be fruitless/not-related.)
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Dec 4, 2007
I have a problem where my users complain that a select statement takes too long, at 90 seconds, to read 120 records out of a database.
The select statement reads from 9 tables three of which contain 1000000 records, the others contain between 100 and 250000 records.
I have checked that each column in the joins are indexed - they are (but some of them are clustered indexes, not unclustered).
I have run the SQL Profiler trace from the run of the query through the "Database Engine Tuning Advisor". That just suggested two statistics items which I added (no benefit) and two indexes for tables that are not involved at all in the query (I didn't add these).
I also ran the query through the Query window in SSMS with "Include Actual Execution Plan" enabled. This showed that all the execution time was being taken up by searches of the clustered indexes.
I have tried running the select with just three tables involved, and it completes fast. I added a fourth and it took 7 seconds. However there was no WHERE clause for the fourth table, so I got a cartesian product which might have explained the problem.
So my question is: Is it normal for such a type of read query to take 90 seconds to complete?
Is there anything I could do to speed it up.
Any other thoughts?
Thanks
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Nov 16, 2007
Hello,
I have a table which when i execute a select statement the execution lucks performance. The table currently has 1000 rows.
Table:
CREATE TABLE [dbo].[Listings](
[ListingID] [int] NOT NULL,
[UserID] [int] NOT NULL,
[NodeID] [int] NOT NULL,
[Title] [varchar](100) NOT NULL,
[Description] [varchar](500) NOT NULL,
[Keywords] [varchar](200) NOT NULL,
[URL] [varchar](150) NOT NULL,
[DateSubmited] [datetime] NOT NULL
) ON [PRIMARY]
Even a simple sql statement without any where clause will take 3 seconds to execute.
select LISTINGID, TITLE, DESCRIPTION from listings
Is there anyway to improve that?
Thanks in advance.
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Jan 24, 2008
I have a table of products which contains a parent-child hierarchy (a self-relationship, creating a built-in recursive structure using a foreign key). The point is: I must create a query that shows only products which are not parents. I can achieve this using a "not in" or a "full join".
Can anybody tell me which of the 2 below is the best option, and why?
Code Snippet
SELECT ProductID
FROM CRP.Product
WHERE ProductID NOT IN
(SELECT ProductFatherID FROM CRP.Product WHERE ProductFatherID is not NULL)
Execution plan:
Select (cost 0%) <--- Merge join (25%) <--- Clustered index scan (54%)
^--- Stream aggregate (1%) <--- Index seek (19%)
Code SnippetSELECT
PC.ProductID
FROM -- Product Child
CRP.Product PC
FULL JOIN -- Product Parent
(SELECT ProductFatherID ProductID
FROM CRP.Product
WHERE ProductFatherID is not NULL) PP ON (PC.ProductID = PP.ProductID)
WHERE
PP.ProductID is NULL
Execution plan:
Select (cost 0%) <--- Filter (2%) <--- Merge join (29%) <--- Clustered index scan (51%)
^--- Compute scalar (0%) <--- index seek (18%)
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Jul 12, 2004
I have only been working with sql server for sever months so I would consider myself a novice.
I am trying to return 3 different datasets from the same query information.
for example a person will do a search for articles on "flowers red annuals"
I first want to return a datase with item details. Name of book, copyright, author etc...
I then want to populate 2 drop down lists to help narrow down the search
1. Article type
Newspaper(count)
Magazine(count)
Hardback Book(count)
Softback book(count)
Etc...
2. Publisher
Publisher A(count)
Publisher B(count)
Publisher C(count)
etc....
I am currently running 3 separate stored procedures against the master file to return this data.
1. select ... for the detail
2. Select ...count() group by for the other 2
Is there a better way to get this information without having to run the query 3 times?
Is there a way to run the (select..group by) against initial detail information to populate the 2 drop down controls.
Is there a way to return more that one dataset of information from one stroed procedure?
Because the data source has millions of records I would assume that this is inefficient or does it matter?
Thanks in advance for any advice.
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Mar 23, 2006
We use an ASP/MS SQL 2000 system to send out our mass e-mailing to about 3,500 subscribers (and the list is growing). There are some duplicate entries in the DB and I was thinking about using this code
SELECT DISTINCT email FROM Subscribers
to remove the duplicates (at least until we can get around to cleaning up the data and then putting up new subscriber form to prevent duplicate entries).
I was wondering, though... Will this have a significant impact on our performance? I mean, that's a lot of e-mail addresses to process and I don't want to bog our system down unnecessarily.
What do you performance gurus think?
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Oct 17, 2007
I am running SQL 2000 SP4. I have a stored procedure which calls a function in an update statement. Previously, this SP which is pretty intensive and used to build a report would run in appox 10 minutes. Now it is taking 3 hours to execute. I have tracked the performance issue to the function. The function is taking 3 to 4 seconds to execute for each row and it is updating 2,600 rows.
I am including the select statement causing problems.
SELECT TOP 1
@m_ECodeMsg = tev.BillMsg
FROM tblUsageHistoryDetail tuhd
INNER JOIN tblMeterReadEcode tmre
ON tmre.MeterReadID = tuhd.CurrentMeterREadID
INNER JOIN tblUsageHistory tuh
ON tuh.UsageHistoryID = tuhd.UsageHistoryID
INNER JOIN tblTran tt
ON tt.TranID = tuh.TranID AND tt.ServiceLocationID = tuh.ServiceLocationID
INNER JOIN tblServiceLocation tsl
ON tsl.ServiceLocationID = tt.ServiceLocationID
INNER JOIN tblRateUsage tru
ON tru.RateID = tsl.RateID
INNER JOIN tblECodeValue tev
ON tev.ECodeValueID = tmre.ECodeValueID AND tev.ECodeTypeID = tmre.ECodeTypeID
WHERE tt.StatementID = @i_StatementID AND tru.AltServiceID = tsl.ServiceID
AND tt.TranTypeID = 2 AND tev.ECodeTypeID = 6
The function has been in use for over a year and SP4 has been installed on this server for serveral months now. If I run this on an old box with SP3a it runs fine. I have rewrote the statement without the "TOP 1" and execution of the function is less than 1 sec.
Any ideas as to why my performance has taken such a hit?
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Jul 11, 2007
Hello -- thank you for taking the time to read this.
I have a very large table that is used both for archives and new information. To get the current information, the table is queried by many different users at various polling periods. The SELECT required includes about fifteen JOINS, and only returns about 200 rows at any given time.
So I got to thinking if it might be faster to periodically run the big query as a SELECT INTO into a smaller table and letting the polling clients query the smaller table with SELECT *. Periodically, the smaller table would be DROPPED and refereshed with another SELECT INTO.
Trouble is, the data would have to be updated once every 30 seconds, and there are inbound polls coming at the rate of about 200 per minute. It got me to thinking what might happen if a client attemtped to query the smaller table when it was in the process of being dropped and refilled.
So my question is three-part:
1) assuming a larger table of about 500,000 records and only 500 pertinent at any given time, is there any real potential of performance enhancement by switching to a SELECT INTO table?
2) if so, is there a chance of a client failing a query if the inbound query somehow collides with the DROP/SELECT INTO procedure?
3) if so, is there any way to prevent it or a better way of doing this?
Thanks again for reading, and in advance for any help you can provide. I apologize if I sound like a dummy - it's hard to fake intelligence!
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Jul 20, 2005
Hi All,I am getting slower performance of select statements in MS SQL. I amfinding select statements in MS SQL are even slower than MS ACCESS. Isthere any way to improve the performance of select statements in MSSQL by tuning the database of anything else??Thanks in advance!Hoque
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Apr 29, 2008
I have a table that contains 10 millions records. The following 2 statements, which one provide better performance? Frankly, i have no idea how to compare the execution plan...
Select Top 10000 * From Table
OR
Set rowcount 10000
Select * From Table
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Mar 29, 2008
OK, I have figured out how to hide the sys views and Information_Schema views from users but before I try it on the live database I have a question:
If I Deny Select on the Master Public Role for the sys views and Information_Schema views, what impact will this have for users other than not being able to see those views? Anyone know this?
Your feedback is greatly appreciated.
Thanks.
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Jul 23, 2005
I've just inherited a system and have some concerns about the speed ofconnections to a remote server (SQL2000). If I do a simple selectstatement on the table below, it takes 14 minutes to retrive 6 millionrows across a 2Mb line. Obviously it's a reasonable amount of data toretrieve, but I would have thought this would be quicker if I'm honest.Run locally, this is 50 seconds.My thoughts are that there may be some issues with our connection (weget general network errors sporadically, which are being looked at),but wanted some thoughts if the performance is acceptable for what itis doing with what is available. I don't think there is a SQL issue,but want to check if this sounds about right.It's early days, so I'm after a general impression of the speed ofretrieval for the amount of data on the available bandwidth. Assuming abest performance scenario, what is the minimum time it should take as abest guess ?ThanksRyanCREATE TABLE [FIELD_VALUES] ([DEALER_DATA_ID] [int] NOT NULL ,[FIELD_CODE] [varchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NOTNULL ,[FIELD_VALUE] [numeric](15, 5) NULL ,[CHANGED_TYPE] [int] NULL ,CONSTRAINT [PK_FIELD_VALUES] PRIMARY KEY CLUSTERED([DEALER_DATA_ID],[FIELD_CODE]) WITH FILLFACTOR = 90 ON [PRIMARY]) ON [PRIMARY]GO
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Nov 28, 2007
Hi.
We are now working with SQL2000sp4, planning migration to SQL2005 in few months though.
I've faced performance issues with large tables (200-500 mln rows, 50-100Gb of data+indexes)
New data are uploaded into tables once a day, around 1mln rows. Thats the only time of inserting data, during daytime tables are used for SELECTs only.
The problem that daily INSERTs are taking too much time now, because of rebuilding few indexes for the table.
I noticed that partitioning solution looks like solving this problem well. So i splitted master data table into 4 tables:
old master table:
CREATE TABLE [dbo].[DTB] (
[report_date] [smalldatetime] NOT NULL ,
[param] [char] (10) COLLATE Cyrillic_General_CI_AS NOT NULL ,
[param_value1] [decimal](18, 2) NULL ,
[param_value2] [decimal](18, 2) NULL ,
[param_value3] [smallint] NULL
)
CREATE INDEX [IX_DTB_DT_ACC] ON [dbo].[DTB]([report_date], [param])
new partition1:
CREATE TABLE [dbo].[be_data_DTB_part_2007_q1] (
[report_date] [smalldatetime] NOT NULL ,
[param] [char] (10) COLLATE Cyrillic_General_CI_AS NOT NULL ,
[param_value1] [decimal](18, 2) NULL ,
[param_value2] [decimal](18, 2) NULL ,
[param_value3] [smallint] NULL ,
CONSTRAINT [CK_be_data_DTB_part_2007_q1_report_date] CHECK ([report_date] >= '2007-Jan-01' and [report_date] <= '2007-Mar-31')
)
CREATE CLUSTERED INDEX [idc_be_data_DTB_part_2007_q1_report_date_param] ON [dbo].[be_data_DTB_part_2007_q1]([report_date], [param])
Similar are definitons for other partitions - q2, q3 and q4.
And here is partitioned view itself:
create view dbo.data_DTB
as
select * from dbo.be_data_DTB_part_2007_q1
union all
select * from dbo.be_data_DTB_part_2007_q2
union all
select * from dbo.be_data_DTB_part_2007_q3
union all
select * from dbo.be_data_DTB_part_2007_q4
I want users to access data SELECTing from view data_DTB, while I perform daily inserts right into be_data_DTB_part_2007_q4.
In general, this solution works well. For example:
Code Block
set statistics profile on
go
select * from data_DTB where report_date = '2007-Apr-16'
go
set statistics profile off
go
1290674 1 SELECT * FROM [data_DTB] WHERE [report_date]=@1
1290674 1 |--Concatenation
0 1 |--Filter(WHERE:(STARTUP EXPR(Convert([@1])<='Mar 31 2007 12:00AM' AND Convert([@1])>='Jan 1 2007 12:00AM')))
0 0 | |--Clustered Index Seek(OBJECT:([MYDB].[dbo].[be_data_DTB_part_2007_q1].[idc_be_data_DTB_part_2007_q1_report_date_param]), SEEK:([be_data_DTB_part_2007_q1].[report_date]=Convert([@1])) ORDERED FORWARD)
1290674 1 |--Filter(WHERE:(STARTUP EXPR(Convert([@1])<='Jun 30 2007 12:00AM' AND Convert([@1])>='Apr 1 2007 12:00AM')))
1290674 1 | |--Clustered Index Seek(OBJECT:([MYDB].[dbo].[be_data_DTB_part_2007_q2].[idc_be_data_DTB_part_2007_q2_report_date_param]), SEEK:([be_data_DTB_part_2007_q2].[report_date]=Convert([@1])) ORDERED FORWARD)
0 1 |--Filter(WHERE:(STARTUP EXPR(Convert([@1])<='Sep 30 2007 12:00AM' AND Convert([@1])>='Jul 1 2007 12:00AM')))
0 0 | |--Clustered Index Seek(OBJECT:([MYDB].[dbo].[be_data_DTB_part_2007_q3].[idc_be_data_DTB_part_2007_q3_report_date_param]), SEEK:([be_data_DTB_part_2007_q3].[report_date]=Convert([@1])) ORDERED FORWARD)
0 1 |--Filter(WHERE:(STARTUP EXPR(Convert([@1])<='Dec 31 2007 12:00AM' AND Convert([@1])>='Oct 1 2007 12:00AM')))
0 0 |--Clustered Index Seek(OBJECT:([MYDB].[dbo].[be_data_DTB_part_2007_q4].[idc_be_data_DTB_part_2007_q4_report_date_param]), SEEK:([be_data_DTB_part_2007_q4].[report_date]=Convert([@1])) ORDERED FORWARD)
As far as i see it checks filter parameter fitting CHECK constraint for each partition. Then it peforms clustered index seek for partition actually containing data and avoids using 3 other partitions. Thats great! This example just illustraits that partitioning actually works for me.
Unfortunately, there is another query with just awful performance on partitions comparing to single table. Lets try to get few rows entered last day:
Code Block
set showplan_text on
go
select top 10 * from DTB order by report_date desc
go
set showplan_text off
go
|--Top(10)
|--Bookmark Lookup(BOOKMARK:([Bmk1000]), OBJECT:([MYDB].[dbo].[DTB]))
|--Index Scan(OBJECT:([MYDB].[dbo].[DTB].[IX_DTB_DT_ACC]), ORDERED BACKWARD)
Excellent! It runs just for only few seconds. But using partitions:
Code Block
set showplan_text on
go
select top 10 * from data_DTB order by report_date
go
set showplan_text off
go
|--Top(10)
|--Merge Join(Concatenation)
|--Merge Join(Concatenation)
| |--Merge Join(Concatenation)
| | |--Sort(ORDER BY:([be_data_ DTB_part_2007_q1].[report_date] ASC, [be_data_ DTB_part_2007_q1].[param] ASC, [be_data_DTB_part_2007_q1].[param_value1] ASC, [be_data_ DTB_part_2007_q1].[param_value2] ASC, [be_
| | | |--Clustered Index Scan(OBJECT:([MYDB].[dbo].[be_data_DTB_part_2007_q1].[idc_be_data_DTB_part_2007_q1_report_date_param]))
| | |--Sort(ORDER BY:([be_data_DTB_part_2007_q2].[report_date] ASC, [be_data_ DTB_part_2007_q2].[param] ASC, [be_data_DTB_part_2007_q2].[prama_value1] ASC, [be_data_DTB_part_2007_q2].[param_value2] ASC, [be_
| | |--Clustered Index Scan(OBJECT:([MYDB].[dbo].[be_data_DTB_part_2007_q2].[idc_be_data_DTB_part_2007_q2_report_date_param]))
| |--Sort(ORDER BY:([be_data_DTB_part_2007_q3].[report_date] ASC, [be_data_DTB_part_2007_q3].[param] ASC, [be_data_DTB_part_2007_q3].[param_value1] ASC, [be_data_DTB_part_2007_q3].[param_value2] ASC, [be_data_
| |--Clustered Index Scan(OBJECT:([MYDB].[dbo].[be_data_DTB_part_2007_q3].[idc_be_data_DTB_part_2007_q3_report_date_param]))
|--Sort(ORDER BY:([be_data_DTB_part_2007_q4].[report_date] ASC, [be_data_DTB_part_2007_q4].[param] ASC, [be_data_DTB_part_2007_q4].[param_value1] ASC, [be_data_DTB_part_2007_q4].[param_value2] ASC, [be_data_
|--Clustered Index Scan(OBJECT:([MYDB].[dbo].[be_data_DTB_part_2007_q4].[idc_be_data_DTB_part_2007_q4_report_date_param]))
As one can see that€™s just awful . When I make graphical execution plan with Ctrl+L it says costs for Sort operations are thousands. I didn€™t run this query to check statistics profile, because on our server it will run for hours.
I found a topic regarding this problem: http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=1270479&SiteID=17
Mostafa Elhemali describes exactly my problem in the last post. I also though that getting top 10 * from partitioned view shouldn€™t be a problem €“ it€™s quite obvious just to grab top 10 from each partition and then find top 10 amongst them. Looks like it doesn€™t work this way though.
So the question is. Is there any new workarounds for this problem? Or maybe it is already solved in latest patches for SQL2005? I know that SQL2005 introduces new way of partitioning tables, maybe the problem will go if using SQL2005 partitioned tables instead of oldstyle partitioned views?
Thank you.
p.s. Upon reviewing my post i noticed that issued ORDER BY report_date DESC against unpartitioned table, and ORDER BY report_date against partitioned view. Well, specifying ORDER BY report_date DESC for partitioned view gives similar results, except for few ASCs are replaced with DESCs.
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Jun 15, 2015
the cursor at the bottom  iterates only to print the number of rows.The problem is in the select. This takes 30 seconds to iterate through 1242 records.But if I add a TOP 1000000 or whatever number to the select, the same iteration takes less than a 1 second.I've tested each query without cursor, and  both have the same cost and performance. (Not exactly the same plan)Note that I got the same performance improvement declaring the cursor as STATIC.Why the top is affecting the cursor iteration so much?
Declare @query varchar(512)
DECLARE Itera CURSOR --LOCAL STATIC READ_ONLY FORWARD_ONLY
FOR
select --TOP 1000000
[code]....
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Dec 10, 2007
Hello, everyone:
I want to add a column, INT NOT NULL DEFAULT 0, to a table. There are about 9 mil. records, 57 columns in the table. SQL 2k on Win 2003. What impact maybe bring?
1) Is there a down time on database and server?
2) Is it possible to insert records during adding new column?
3) How long will be taken roughly?
Thanks a lot.
ZYT
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Oct 25, 2006
SQL 2000 Connection String:user id=MyUserName;password=MyPassword;initial catalog=MyDB;server=MyServer;Connect Timeout=30 This SELECT statement returns its 10 results nearly instantly:SELECT * FROM MyTableDitto from above, but completes in 30-40 seconds:SELECT * FROM [dbo].[MyTable]Ditto from above, but completes nearly instantly:
SELECT TOP 1000 * FROM [dbo].[MyTable] Obviously I have stopped using the [dbo] syntax in my SqlCommand's (SELECT's and EXECUTE's) but still would like to know why this is.vr, Rich
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Sep 13, 2005
For some reasons I need to access the same field of the same table twice in a query, and each give out a diferrent valueLike this:"SELECT myTable.id, myTable1.id as subID FROM myTable INNER JOIN ... INNER JOIN myTable as myTable1 ..."The question is, when I write it as myTable as myTable1 will it affect the query performance if myTable is a large table? will it create another so big copy of myTable? or I should create a view like "CREATE VIEW myTable1 AS SELECT id FROM myTable" to reduce the side of myTable1?Thank you.
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Feb 22, 2008
Hello,
I have the following queries that run on a view called EntrySummary:
1)
exec sp_executesql N'SELECT COUNT (1) FROM [dbo].[EntrySummary] WHERE [EntrySummary].[SubmissionStatusID] = @SubmissionStatusID0 AND [EntrySummary].[CreatedBy] = @CreatedBy1',N'@SubmissionStatusID0 int,@CreatedBy1 nvarchar(20)',@SubmissionStatusID0=4,@CreatedBy1=N'domainaperson'
2)
exec sp_executesql N'SELECT COUNT (1) FROM [dbo].[EntrySummary] WHERE [EntrySummary].[CreatedBy] = @CreatedBy1 AND [EntrySummary].[SubmissionStatusID] = @SubmissionStatusID0',N'@SubmissionStatusID0 int,@CreatedBy1 nvarchar(20)',@SubmissionStatusID0=4,@CreatedBy1=N'domainaperson'
(The only difference between the two queries being the order of the where clauses)
Both return the correct answer (4144), but Query 2 takes 10-15 seconds whereas Query 1 takes < second.
If the same query is resubmitted several times, this doesn't affect the times.
(The vast majority of the records have a status of 4, but only about 3% will be created by the person).
Replacing Count(1) with count(*) makes both queries return quickly.
Is sp_executesql creating poor execution plans ? Can anyone explain this behaviour?
Regards,
AndyM
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Jun 22, 2015
I have encountered a problem with a specific set of tables. The same select yields slightly differing execution plans in two different environments (instances). But the slight variation seems to contain a huge differences in stats. I don't know the significance of these stats. The two tables have the exact same indices.
This is the selcet statement:
SELECT 'xx' FROM DUKS.dbo.Profiler
WHERE DNA_Løbenummer IN
(SELECT DNA_Løbenummer FROM DUKS.dbo.Effektregister
WHERE Sagsnummer = '2015-00002')
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Jul 3, 2001
Hi All,
I want to know what will be the impact of changing the primarykey on a table which already has a lot of data.
For example, column A is unique, primary key. I want to make column B as unique, primary key.
Can I do that? What will be the impact on database performance?
Thanks
Sri
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Oct 4, 2006
Hi,
I am looking for a tool that is similar to SQL Impact (Quest). Quest has discontinued the tool.
This tool should be able to detect all database object dependencies for SQL Server, Sybase and Oracle. The objects should include tables, views, stored procedures, indexes and other objects. This should also detect DB object dependencies in front end applications as well.
Any suggestions are greatly appreciated...
Thanks!
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Jan 24, 2008
Hi,
Does anyone know how the key influencers impact values are calculated? Thanks!!
Kate
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May 13, 2008
Hi,
I am currently working on with the ASP encryption of my application. I've tried to test the encryption of the connection string using the capicom.dll in my local, and it works successfully. However, I am not quite sure if this will still work after my OS is upgraded to WIN2K3 (my current OS is WINXP). Will this dll component be impacted after the OS Upgrade? or will there be no impact at all?
Any inputs from you guys would be much appreciated.
Thank you.
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Mar 12, 2008
Hi all
I have a Large log table with large size data(I month only),If I run a query like SELECT * FROM <table_name> Server will go€¦very very slow€¦.
Because of large Data system is going slow€¦..
Please some body helps me with suggestion how get good performance.
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Jan 4, 2005
Thanks to all participants.
I am using SQL Server 2000 with replication object for two location. Log size on publisher go upto 25 times of data file size, I mean 80 MB Data files has maintains 2 GB log file and it is same for all five co's working on same windows 2000 advanced server board.
Since last week server randamly get disconnected from user applications and at that time few tables are not openable at server.
Can any one give a reason ? Why this type misbehaviou done by SQL Server 2000?
Thanks.
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Jul 13, 2007
I have a question regarding FUll and differential backup.
We we take full or diff back up, does it create lot of logs ie. Does full or diff backup has any impact on log size?
Thanks
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Sep 1, 2007
We have the following scenario:
Server A replicates Database A to Server B.
Server C has Database A on it as well, but in standby mode. We are applying the transaction logs generated by Database A on Server A to the database on Server C leaving it in standby mode each time.
Let's say we had planned maintenance for Server Aand dumped the last set of transactions on Server A in standby mode to be applied to to Server C. What happens to the replica on Server B? When I start to use Server C, can I backup its transactions and apply them to Server A, and then have those transactions replicated to Server B? And then what do I do when the maintenance is complete so that I can swithc back to Server A and have the replication continue on as before the maintenance to Server B?
Thanls
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May 17, 2015
What would happen to the the queries which are under execution when I change the MAXDOP value from say 0 to 1?
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