Multiple Optimization Hints
Sep 3, 1999I need to use two hints (INDEX=indexname) and (NOLOCK).
I've tried
(INDEX=indexname),(NOLOCK)
(INDEX=indexname,NOLOCK)
(INDEX=indexname)(NOLOCK)
and nothing works.
Thanks
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Table Data Retrieval And Optimization Optimization Help
Apr 10, 2008Hello Everybody,
I have a small tricky problem here...need help of all you experts.
Let me explain in detail. I have three tables
1. Emp Table: Columns-> EMPID and DeptID
2. Dept Table: Columns-> DeptName and DeptID
3. Team table : Columns -> Date, EmpID1, EmpID2, DeptNo.
There is a stored procedure which runs every day, and for "EVERY" deptID that exists in the dept table, selects two employee from emp table and puts them in the team table. Now assuming that there are several thousands of departments in the dept table, the amount of data entered in Team table is tremendous every day.
If I continue to run the stored proc for 1 month, the team table will have lots of rows in it and I have to retain all the records.
The real problem is when I want to retrive data for a employee(empid1 or empid2) from Team table and view the related details like date, deptno and empid1 or empid2 from emp table.
HOw do we optimise the data retrieval and storage for the table Team. I cannot use partitions as I have SQL server 2005 standard edition.
Please help me to optimize the query and data retrieval time from Team table.
Thanks,
Ganesh
Hints ?
Jun 16, 2004Is there anything equivalent available in SQL Server for Oracle HINTS ?
eg : Oracle query
select /* + INdex(sno index1) */ sno from test_table
Thanks,
Sam
Hints
Jul 23, 2005I am kind of confused about the way SQL Server 2000 handles the hintsthat users supply with their SQL statements.[color=blue]>From BOL, it seems that one can specify them with "WITH (...)" clauses[/color]in SQL statements known as table hints. Sometimes, multiple uses ofthis form in a statement is OK. Then there is the OPTION clause forspecifying statement hints. However, the documentation on OPTIONsection discourages their use.Being relatively new to SQL Server and still learning about it, what isthe general practice? Use hints or not? And if so, how (through WITHor OPTION clauses)?Cheers!
View 5 Replies View RelatedQuery Hints
Sep 12, 2005My experience with query hints are that they are just that, a hint. What I don't understand is when does SQL decide to ignore your hint?
Index Hints
May 15, 2001I am running SQL7 SP2 and and noticing table the query processor table scans when I ussue a between 'date1' and 'date2' instead of using the datetime index. If I put in the index hint (index = ix_datetimeXXXX) the query runs fine. My question is does this index hint restict the use of other indexes in the query and secondly how can I specify multiple index hints? Thanks in advance.
View 1 Replies View RelatedQuery Hints
Sep 29, 2003Please advise.
Whilst running a query I recieved the error below.
Cannot create a worktable row larger than allowable maximum. Resubmit your query with the ROBUST PLAN hint.
What is ROBUST PLAN hint?.
Help Appreciated.
Locking Hints
May 1, 2007Hi
My VB.Net (with SQL Server backend) application currently allows more than one user to look at a particular record at the same time. This is not a problem unless both those users also try to update that record as well. One user's changes then overwrite the other's.
I've been reading up on locking hints but my database knowledge is a little scant and I'm also rather dense and need things spelling out for me!! So I have a few questions that I hope someone can help with:
If I add an updlock to my update SQL statement, this would allow both users to view the record but would only allow one user's changes through. Is that correct?
For the other user, would SQL Server return an error message that I can use to tell the user that their update has not worked?
Would I have to get my VB.NET application to re-get the record information so that the user who's update failed can see the changes made by the other user and reapply their own changes?
Does the updlock become unlocked once the record is updated or do I need to specifically unlock it somehow?
Thanks!
BUG With Join Hints
Apr 20, 2007I am having problems with doing what seams to be a very easy query. For some reason the SQL Server is trying to do nested loops instead of hash join. I tried to force the use of the hash join using the join hint.
Query 1
select *
from DIM_DATE DD
inner hash join (
select A.student_key,
CONVERT(int, CONVERT(varchar, COALESCE (A.date_withdrawn, getdate()), 112)) AS date_withdrawn_current
FROM FACT_STUDENT AS A
) SSE on DD.date_key= date_withdrawn_current
This query gives an error:
Msg 8622, Level 16, State 1, Line 1
Query processor could not produce a query plan because of the hints defined in this query. Resubmit the query without specifying any hints and without using SET FORCEPLAN
Second query is not really what I want but it illustrate that it works fine when getdate() is not used.
Query 2
select *
from DIM_DATE DD
inner hash join (
select A.student_key,
CONVERT(int, CONVERT(varchar, COALESCE (A.date_withdrawn, A.date_enrolled), 112)) AS date_withdrawn_current
FROM FACT_STUDENT AS A
) SSE on DD.date_key= date_withdrawn_current
Is there some problem with using function getdate() ? It works fine in SQL Server 2000
This problem occurs on the SQL Server 2005 SP2 ( 9.00.3050.00 (X64) )
and (9.00.2050)
Confused About Using Lock Hints?
Mar 19, 2006I noticed that the online books say the following:
Note The SQL Server query optimizer automatically makes the correct determination. It is recommended that table-level locking hints be used to change the default locking behavior only when necessary.
Also, at another place in online books, it says:
The table hints are ignored if the table is not accessed by the query plan.
From the above, it seems that using locking hints is not going to guarantee that SQL Server will follow them. Is this true?
JOIN Hints: Why SQL Works As Follows?
Sep 9, 1998Hi,
Why SQL server dose work as follows when I dose not provide any join hints?
It looks like HASH join is the best plan, but SQL dose not. What kind of
JOIN method is used by SQL optimizer?
Thanks in advance,
Wonhyuk William Chung
wonhyukc@usa.net
MCSE/ MCT
-----------
use northwind
go
select orderid, CompanyName --productname,
from orders o inner join customers c on o.customerID = c.CustomerID
/*
Table `Orders`. Scan count 91, logical reads 184, physical reads 0,
read-ahead reads 0.
Table `Customers`. Scan count 1, logical reads 1, physical reads 0,
read-ahead reads 0.
.0553
*/
select orderid, CompanyName --productname,
from orders o inner hash join customers c on o.customerID = c.CustomerID
/*
hash
Table `Customers`. Scan count 1, logical reads 1, physical reads 0,
read-ahead reads 0.
Table `Orders`. Scan count 1, logical reads 4, physical reads 0, read-ahead
reads 0.
.115
*/
select orderid, CompanyName --productname,
from orders o inner merge join customers c on o.customerID = c.CustomerID
/*
merge
Table `Customers`. Scan count 1, logical reads 4, physical reads 1,
read-ahead reads 3.
Table `Orders`. Scan count 1, logical reads 4, physical reads 0, read-ahead
reads 0.
.115
*/
select orderid, CompanyName --productname,
from orders o inner loop join customers c on o.customerID = c.CustomerID
/*
loop
Table `Customers`. Scan count 830, logical reads 1681, physical reads 0,
read-ahead reads 0.
Table `Orders`. Scan count 1, logical reads 5, physical reads 0, read-ahead
reads 0.
.116
*/
Reason To Use Optimizer Hints
Aug 5, 1999While investigating performance problems within an application recently I carried out some tests using SET SHOWPLAN ON.
I had a query like this within a stored procedure:
SELECT MAX(X) FROM Y WHERE Z LIKE @MYVAR
Where @MYVAR was passed in. I discovered that SQL Server did a Table Scan even when Z had an index on it. A problem with 200,000 rows!
If I said
SELECT MAX(X) FROM Y WHERE Z LIKE 'HELLO%'
(i.e., used a constant instead of a variable) SQL Server did use the index correctly and did not do a table scan.
I got around this by rewriting my statement:
SELECT MAX(X) FROM Y (INDEX=MYINDEX) WHERE Z LIKE @MYVAR
in other words by manually specifying the index I had created on the Z column.
Hope this helps someone.
Subquery Woes; Hints ?
Feb 9, 2008hi all,
I'm trying to run queries on relatively small tables (a few hundred thousand rows) with subqueries of counts per primary key columns as such:
(ColA in tableA is the primary key)
select * from tableA p
where exists (select 1 from ( select ColA, count(1) cnt
from TableA
group by ColA
having count(1)>1 ) t
where t.ColA= p.ColA)
order by some_col
my problem is that sqlserver 2005 sp5 does not materialize the internal subquery properly, or execute it beforehand and it gets confused as heck and pegs the CPUs at 100% forever.
What hints can I use to solve this issue?
I've tried to use ..... "with ...." to prepare/materialize the table upfront, no luck, one version of statement pegged one cpu at 100%, while the other statement pegged ALL cpu's at 100% -- don't remember which.
My only solution right now was to create these subqueries as PHYSICAL tables -- and this would solve the problem but that would entail creating a lot of un-necessary objects.
thanks much for any feedback!!
Cos
Traceflag To Ignore Index Hints
Jul 23, 2001Hello.
There is a trace flag that tells SQL Server to ignore index hinting in incoming queries. I'm having a Monday morning problem and I can't remember the trace number nor find it in my notes. Can anyone else come up with it?
Thanks in advance,
-darin
Lots Of Txt Files Has To Be Loaded (hints??)
Aug 18, 2006have a dts package that does txt -> sql server.
i have 200 txt files with the same exact format.
just want to know if i can write a SP passing a parameter that loads this txt files. because i dont wanna create 200 packages or 200 sources to load 200 txt files.
say:
exec SP_loadTXT txt1
or should i use bulk insert?
any approaches are fine. any suggestions are fine too.
SQL Seems To Ignore UPDLOCK && ROWLOCK Hints
Dec 3, 2007
I've got a SELECT WITH (UPDLOCK, ROWLOCK) WHERE followed by an UPDATE WHERE statement. The results of the SELECT statement are deserialized in C# and updates are made to the deserialized object. Then the object is serialized back into the table with the UPDATE statement. I've got this code running within a transaction scope with the ReadCommited isolation level.
My service receives requests to update data and the requests can come in on different threads. What I'm seeing, is that once in a while, the log messages from my application indicate that two different threads are able to issue the above SELECT statement and both are receiving results. This is a problem since the thread that issues the last UPDATE will overwrite the changes made by the first. Each thread has its own connection and transaction scope.
I've researched all over the place and have tried a few different things, but all things point to the fact that query hints are just hints and that SQL may or may not pay attention to them. If that's the case, how am I suppose to perform a SELECT with the intention of updating so that no one else can do the same? I haven't tried table level locking, but I'd really like to avoid that if possible.
-Mike
Join Filter Causes Conflicting Locking Hints
Jul 14, 2006Hi,
Using Merge replication, I have a table that is filtered using the HOST_NAME() function. The filter also makes use of a function (as the HOST_NAME() is overriden to return some complex data).
Everything replicates and filters just fine. but when I add a join filter on a different table (the join filter is a simple foreign key join) I get the following error when the snapshot agent is run:
Message: Conflicting locking hints are specified for table "fn_GetIDList". This may be caused by a conflicting hint specified for a view.
Command Text: sp_MSsetup_partition_groups
Parameters: @publication = test1
fn_GetIDList is the function used in the original filter.
Thanks for any help
Graham
Table And Query Hints Not Working In SSCE 3.1 ?
Aug 23, 2007I am trying to use hints and they don't seem to be working.
Something like:
select * from TABLE_NAME with (tablock,xlock)
fails.
Documentation clearly states that this is supported (TABLOCK, NOLOCK, XLOCK, etc.), so I must be missing something simple.
Please let me know how do I use Hints in SQL Server 2005 Compact.
Thanks.
PS.
I am using C#. It doesn't work in my code when I use
SqlCeDataReader rs = cmd.ExecuteReader();
And it doesn't work from inside the VS 2005 "query tool" or whatever it is called, when you do "Connect to Database" and so on.
Using Lock Hints In Query In An OLE DB Command Component
Dec 3, 2007Do you know of a way, in the OLE DB Command (Executing a sql command for each record), to specify a lock hint?
Example: in my component, I want to update a table but I want to specify a ROWLOCK or UPDLOCK hint.
When I try using this sql statement in the 'SqlCommand' property:
UPDATE DIM_Accounts WITH (UPDLOCK)
SET COL1 = ''
SSIS gives a syntax error.
Do you know any workarounds?
Thanks!
Standard Packages - Where To Store? Hints Needed
Jul 25, 2006Hi,
I would like to implement a kind of standard packages which can be used in all other processes and will be started using the variables.
But I do not know where to store these kind of packages in "best practise", because we
- would like to use them in Dev and in "Real" also without having to change something in the other processes
- we are storing the packages in the folders of the package store
and as far as I understood I would have to share the package store to all developers though that they would be able to do this?
Then I would better choose another folder with defined access rights I think...
Or would it be better to spend some time in developing a custom component?
But this component would work with recordsets rather than the standard data flow elemtents and therefor I would expect a leak of performance...
Or is it possible to do "trasnformation" from a packae to a custom component?
Thanks in advice!
cheers,
Markus
Queue Processing Using Updlock, Readpast Locking Hints
Apr 25, 2008This article instructed me on how to process rows from a table used as a data queue for multiple processes.
http://www.mssqltips.com/tip.asp?tip=1257
I tested this against the AdventureWorks DB (SQL 2005) and multiple SQL connections inside of Sql Mgmt. Studio).
Connection1:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) --skips over locked rows
--COMMIT TRANSACTION
Connection2:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) --skips over locked rows
COMMIT TRANSACTION
This works like I want where connection 2 skips over the locked row from connection 1 and gets the next available record from the table / queue. However, when I add ORDER BY tsql to each sql statement, connection 2 is now blocked waiting for Connection 1 to commit. (This is not what I want)
Connection1:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) order by DueDate
--COMMIT TRANSACTION
Connection2:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) order by DueDate --is blocked until connection 1 commits transaction
COMMIT TRANSACTION
How do I prevent blocking when using these locking hints with ORDER BY?
thanks
SQL 2005: Query Is Not Using Non-clustered Index! Need To Avoid Hints!
Oct 26, 2006Greetings,
I have two tables:
CustomerOrder
----
ID
CustomerID
StatusID
CustomerOrderDetail
----
ID
Order_ID
StockID
Quantity
CustomerOrderDetail table has clustered unique index for ID and non-clustered for Order_ID
SQL Server 2005 is using table scan for CustomerOrderDetail table When I user the following query:
select
cod.*
from CustomerOrder co
inner join CustomerOrderDetail cod ON cod.Order_ID = co.ID
where
co.StatusID = 8 -- Pending
Both of the tables are pretty big, detail table has more than million records, so scanning the table is a bad idea.
When I specify hint to use index then sql seeks, but how do I make SQL server to use index automatically? I don't want to use hints in my queries.
Thanks!
Need Optimization
Jun 6, 2007Dear Advance,I used one stored procedure to retrive 3 different result set. and in the codebehind i seperate it. means from the dataset i seperate three different datatable and then show my data as my need.but the main problem is ... after retriving the datafrom the database i have to user foreach loop to bind the coulmns data to my different custom class.example: foreach (DataRow oDrow in MyDataTable.Rows) {oClass=new Class();oClass.Name1=oDrow["Name1"] .toString();oClass.Name2=oDrow["Name2"] .toString();.... } 1. so my first question is there any optimization possible ?2. my result set is too loong ... so should keep just one hit to database or hit more than one time Currently i am optimizing my web application. in the previous version 1 have to hit the database 3/4 times for different purposes. but now it hits only one time... but it takes time in the codebehind to perform different operation.Any Suggestion
View 1 Replies View RelatedOptimization Of An SP
Dec 11, 2001I have a SP that calls about 10 stored procedures sequentially. The 10 SP's are basically complex update statements, each one individual. Is there any way to optimize this?
I know putting the 10 into 1 SP would make it compile faster but thats about it. Are there any execution tricks of Stored Procedures firing off sequentially?..or anything I should know?
-thanks
Bartman
Optimization
Mar 2, 2001Hello All,
What is the best way to optimize this code or rewrite it using ISNULL ?
CREATE PROCEDURE get_employees (@dept char(8), @class char(5))
AS
IF (@dept IS NULL AND @class IS NOT NULL)
SELECT * FROM employee WHERE employee.dept IS NULL
AND employee.class=@class
ELSE IF (@dept IS NULL AND @class IS NULL)
SELECT * FROM employee WHERE employee.dept IS NULL
AND employee.class IS NULL
ELSE IF (@dept IS NOT NULL AND @class IS NULL)
SELECT * FROM employee WHERE employee.dept=@dept
AND employee.class IS NULL
ELSE
SELECT * FROM employee WHERE employee.dept=@dept
AND employee.class=@class
Thanks in advance.
-Praveena
Optimization
Jul 6, 2001I am wondering if the size of the data file makes a difference in running Insert's and/or doing Fetch's. Our DB was 11GB in size, I ran a dbcc shrinkdatabase and it shrank it to 5.5 GB in size, now that it is smaller will it run a select query faster as opposed to when we run large inserts and it has to automatically grow to accommodate the insert. I am trying to figure out if I should leave my .mdf file large or keep it small or does it even make a difference. I am only doing large inserts while loading data to get ready for production after that the inserts will be hourly but much smaller, however our queries to the DB after it is in production will be much more intensive.
Hope this makes sense. Appreciate your help.
Optimization
Jan 9, 2006Hi All,
I am writing a script that runs the optimization process. I am not sure how to test it? Any help is greatly appreciated.
SQL Optimization
Dec 20, 2006Hello,
Is there a tool to optimize SQL procedures code?
Thanks,
Miguel
Optimization
Jul 20, 2005We're building a company wide network monitoring systemin Java, and need some advice on the database design andtuning.The application will need to concurrently INSERT,DELETE, and SELECT from our EVENT table as efficiently aspossible. We plan to implement an INSERT thread, a DELETEthread, and a SELECT thread within our Java program.The EVENT table will have several hundred million recordsin it at any given time. We will prune, using DELETE, aboutevery five seconds to keep the active record set down toa user controlled size. And one of the three queries willbe executed about every twenty seconds. Finally, we'llINSERT as fast as we can in the INSERT thread.Being new to MSSQL, we need advice on1) Server Tuning - Memory allocations, etc.2) Table Tuning - Field types3) Index Tuning - Are the indexes right4) Query Tuning - Hints, etc.5) Process Tuning - Better ways to INSERT and DELETE, etc.Thanks, in advance, for any suggestions you can make :-)The table is// CREATE TABLE EVENT (// ID INT PRIMARY KEY NOT NULL,// IPSOURCE INT NOT NULL,// IPDEST INT NOT NULL,// UNIXTIME BIGINT NOT NULL,// TYPE TINYINT NOT NULL,// DEVICEID SMALLINT NOT NULL,// PROTOCOL TINYINT NOT NULL// )//// CREATE INDEX INDEX_SRC_DEST_TYPE// ON EVENT (// IPSOURCE,IPDEST,TYPE// )The SELECTS areprivate static String QueryString1 ="SELECT ID,IPSOURCE,IPDEST,TYPE "+"FROM EVENT "+"WHERE ID >= ? "+" AND ID <= ?";private static String QueryString2 ="SELECT COUNT(*),IPSOURCE "+"FROM EVENT "+"GROUP BY IPSOURCE "+"ORDER BY 1 DESC";private static String QueryString3 ="SELECT COUNT(*),IPDEST "+"FROM EVENT "+"WHERE IPSOURCE = ? "+" AND TYPE = ? "+"GROUP BY IPDEST "+"ORDER BY 1 DESC";The DELETE isprivate static String DeleteIDString ="DELETE FROM EVENT "+"WHERE ID < ?";
View 2 Replies View RelatedAbout Optimization?
Jul 17, 2007There are two main tables in my app,in order to optimize search via scope condition, I set many indexs for these two tables
however,at the same time the two tables are also used for my etl app,everyday there are more than thousands of data need to be updated or inserted, but index is not suitable for huge modification,any idea about how to handle this?
thanks in advance
Optimization
Oct 15, 2007
Hello,
what is the meaning about <MissingIndexGroup Impact="99.9521"> in the Queryplan? Should I create a Grouped Index? An what is the meaning about Impact="99.9521"?
If the Impact =100 you get a 100% better performance, and if the impact =20 ypu get a 20% better performance, is this the meaning?
finchen
Query Optimization - Please Help
Aug 15, 2007Hi,
Can anyone help me optimize the SELECT statement in the 3rd step? I am actually writing a monthly report. So for each employee (500 employees) in a row, his attendance totals for all days in a month are displayed. The problem is that in the 3rd step, there are actually 31 SELECT statements which are assigned to 31 variables. After I assign these variable, I insert them in a Table (4th step) and display it. The troublesome part is the 3rd step. As there are 500 employees, then 500x31 times the variables are assigned and inserted in the table. This is taking more than 4 minutes which I know is not required :). Can anyone help me optimize the SELECT statements I have in the 3rd step or give a better suggestion.
DECLARE @EmpID, @DateFrom, @Total1 .... // Declaring different variables
SELECT @DateFrom = // Set to start of any month e.g. 2007-06-01 ...... 1st
Loop (condition -- Get all employees, working fine)
BEGIN
SELECT @EmpID = // Get EmployeeID ...... 2nd
SELECT @Total1 = SUM (Abences) ...... 3rd
FROM Attendance
WHERE employee_id_fk = @EmpID (from 2nd step)
AND Date_Absent = DATEADD ("day", 0, Convert (varchar, @DateFrom)) (from 1st step)
SELECT @Total2 ........................... same as above
SELECT @Total3 ........................... same as above
INSERT IN @TABLE (@EmpID, @Total1, ...... @Total31) ...... 4th
Iterate (condition) to next employee ...... 5th
END
It's only the loop which consumes the 4 minutes. If I can somehow optimize this part, I will be most satisfied. Thanks for anyone helping me....
SQL Connection Optimization
Jun 23, 2004Hi guys,
Could any one tell me what is the best way to declare a connection from ASP .net to a SQL database so the sql could support the maximum users, because it seems that the way i'm using is not correct cuz when i make some transactions from my website to the database, the database send an error message saying that there are no more free connections.
Thnx