I would like to know the impacts (if any) of adding nonclustered index with included columns on large tables (these tables are populated by bulk insert from text files).
View 3 RepliesI am trying to tune a process that is running slowly. I analyzed the process using the Database Engine Tuning Advisor, and it recommended the creation of 3 indexes, all non-clustered:
1) ColA, include ColB
2) ColA, include ColC
3) ColA, include ColD
So... I created a single non-clustered index on:
4) ColA, include ColB, ColC, ColD
That should do the same thing, right? A look at my execution plan shows that the index I created is being scanned -- 3 times. What is puzzling me, though, is that the Database Engine Tuning Advisor is still recommending I create these 3 separate indexes, even with the index (4) that I created in existence.
If it matters, ColA, ColB, ColC and ColD are all int FKs.
Hi, all experts here,
Thanks a lot for your kind attention.
As I am creating the non-clustered indexes for the tables, I dont quite understand how dose it really matter to put the columns in the index key columns or put them into the included columns of the index?
I am really confused about that and I am looking forward to hearing from you and thank you very much again for your advices and help.
With best regards,
Yours sincerely,
I have large table with 10million records. I would like to create clustered or non-clustered index.
What is the quick way to create? I have tried once and it took more than 10 min.
please help.
I'm using sys.dm_db_missing_index_details to find missing indexes on a database that is currently in testing. After running a bunch of our reports, there are several suggested indexes on 3 or 4 columns that have 15 - 20 included columns. The included columns are mostly varchars ranging from 1 to 150 characters along with a couple of date columns. My index size on that table is already nearly twice the size of the data.
I don't think it's a good idea to add an index with that many columns, but the information I've read on included columns is very general. I'm wondering if there is something about them that I don't understand that would make this a good idea.
I need to create a Clustered Index (CI) on a very large SQL Server 2012 database table. This table has about approximately 10 billion rows, 500 GB in size. The job ran for about 20 hours into it and then fails with error: "Out of disk space in tempdb". My tempDB size is 1.8TB, but yet it's still not enough.
Here is my script:
CREATE CLUSTERED INDEX CI_IndexName
ON TableName(Column1,Column2)
WITH (MAXDOP= 4, ONLINE=ON, SORT_IN_TEMPDB = ON, DATA_COMPRESSION=PAGE)
ON sh_WeekDT(Day_DT)
GO
I have a table<table1> with 804668 records primary on table1(col1,col2,col3,col4)
Have created non-clustered index on <table1>(col2,col3,col4),to solve a performance issue.(which is a join involving another table with 1.2 million records).Seems to be working great.
I want to know whether this will slow down,insert and update on the <table1>?
the query:
SELECT a.AssetGuid, a.Name, a.LocationGuid
FROM Asset a WHERE a.AssociationGuid IN (
SELECT ada.DataAssociationGuid FROM AssociationDataAssociation ada
WHERE ada.AssociationGuid = '568B40AD-5133-4237-9F3C-F8EA9D472662')
takes 30-60 seconds to run on my machine, due to a clustered index scan on our an index on asset [about half a million rows]. For this particular association less than 50 rows are returned.
expanding the inner select into a list of guids the query runs instantly:
SELECT a.AssetGuid, a.Name, a.LocationGuid
FROM Asset a WHERE a.AssociationGuid IN (
'0F9C1654-9FAC-45FC-9997-5EBDAD21A4B4',
'52C616C0-C4C5-45F4-B691-7FA83462CA34',
'C95A6669-D6D1-460A-BC2F-C0F6756A234D')
It runs instantly because of doing a clustered index seek [on the same index as the previous query] instead of a scan. The index in question IX_Asset_AssociationGuid is a nonclustered index on Asset.AssociationGuid.
The tables involved:
Asset, represents an asset. Primary key is AssetGuid, there is an index/FK on Asset.AssociationGuid. The asset table has 28 columns or so...
Association, kind of like a place, associations exist in a tree where one association can contain any number of child associations. Each association has a ParentAssociationGuid pointing to its parent. Only leaf associations contain assets.
AssociationDataAssociation, a table consisting of two columns, AssociationGuid, DataAssociationGuid. This is a table used to quickly find leaf associations [DataAssociationGuid] beneath a particular association [AssociationGuid]. In the above case the inner select () returns 3 rows.
I'd include .sqlplan files or screenshots, but I don't see a way to attach them.
I understand I can specify to use the index manually [and this also runs instantly], but for such a simple query it is peculiar it is necesscary. This is the query with the index specified manually:
SELECT a.AssetGuid, a.Name, a.LocationGuid
FROM Asset a WITH (INDEX (IX_Asset_AssociationGuid)) WHERE
a.AssociationGuid IN (
SELECT ada.DataAssociationGuid FROM AssociationDataAssociation ada
WHERE ada.AssociationGuid = '568B40AD-5133-4237-9F3C-F8EA9D472662')
To repeat/clarify my question, why might this not be doing a clustered index seek with the first query?
I have a table with clustered index on that. I have only 5 columns in that table. Execution plan is showing that Index scan occurred. What are the cause of the Index scan how can we change that to index seek?
I am giving that kind of similar query below
SELECT @ProductID= ProductID FROM Product WITH (NOLOCK) WHERE SalesID= '@salesId' and Product = 'Clothes '
Hello!!
Can any one help me out how to find the list of tables those do not have the cluster indexes on it.
TIA,
Paul
Is there any reason why only heaps can have forwarded records while tables with clustered index have to resort to page split when a page becomes saturated with data due to an update or insertion? Both have drawbacks, forwarded records add another level of indirection, leading to increased I/O overhead, while page split may cause further split in the parent pages which can cascade even further. May be that the cascading is a one-time only cost to be incurred, while the indirection overhead repeats everytime there is a query. Then why not go for page split in heap also? The additional overhead to be had for adding another pointer to the IAM page is also one-time.
View 2 Replies View RelatedI need to find out all the tables in database, which has FK columns and don’t have any Non-clustered index on them.
View 11 Replies View RelatedJust wonder if system base tables always use clustered index? I am using SQL Server 2005 and find sys.sysidxstats base table is using heap, not clustered index. Why?
View 2 Replies View RelatedWhat is the best procedure/sequence to reduce some tables containing large number of rows of
a SQL 2000 server?
The idea is first to check which tables grow extremely fast (all statistics, user or log tables), reduce the table
according to the number of months the user wishes to keep in the table.
As a second step backup remaining rows of table as txt files on harddisk (using DTS), UPDATE STATISTICS and re-indexing reduced table.
Run DTS Package every month once (delete oldest month and backup newest month) and do the same as above to keep size of tables adequate.
What is a fast way to reduce number of rows of a large table - the following example produces an error (timeout expired) of my
ADO connection when executing:
SET @str = 'DELETE FROM ' + @ProcessTable + ' WHERE ' + @SelectedColumn + ' < DATEADD (m,' +' -' +
@KeepMonthsInDatabase + ',
+ GETDATE())'
EXEC (@str)
Adding ConnectionTimout = 0 did not help unfortunately.
What is the best way to re-index the table just maintained?
Thanks
mipo
We are having very big tables in TBS and wanted to setup a strategy for index maintenance.
View 3 Replies View RelatedI created columnstore index on the table with 20 columns and about 1000 000 000 rows
every day added about 5M rows
"select" queries became faster because of batch mode and table demand less disk space then before
I have also 6 similar tables with 5 000 000 000 rows and plan to move them on columnstore index
server has 128 G RAM
What pitfalls I could face if I will have so many columnstore indexes on one server?
How a could see problems in DMV?
We are going to use SQL Sever change tracking. The problem is that some of our tables, which are to be tracked, have no primary keys. There are only unique clustered indexes. The question is what is the best way to turn on change tracking for these tables in our circumstances.
View 4 Replies View RelatedI desire to have a clustered index on a column other than the Primary Key. I have a few junction tables that I may want to alter, create table, or ...
I have practiced with an example table that is not really a junction table. It is just a table I decided to use for practice. When I execute the script, it seems to do everything I expect. For instance, there are not any constraints but there are indexes. The PK is the correct column.
CREATE TABLE [dbo].[tblNotificationMgr](
[NotificationMgrKey] [int] IDENTITY(1,1) NOT NULL,
[ContactKey] [int] NOT NULL,
[EventTypeEnum] [tinyint] NOT NULL,
[code]....
I have created two tables. table one has the following fields,
Id -> unique clustered index.
table two has the following fields,
Tid -> unique clustered index
Id -> foreign key of table one(id).
Now I have created primary key for the table one column 'id'. It's created as "nonclustered, unique, primary key located on PRIMARY". Primary key create clustered index default. since unique clustered index existed in table one, it has created "Nonclustered primary key".
My Question is, What is the difference between "clustered, unique, primary key" and "nonclustered, unique, primary key"? Is there any performance impact between these?
Hi there, I have a table that has an IDENTITY column and it is the PK of this table. By default SQL Server creates a unique clustered index on the PK, but this isn't what I wanted. I want to make a regular unique index on the column so I can make a clustered index on a different column.
If I try to uncheck the Clustered index option in EM I get a dialog that says "Cannot convert a clustered index to a nonclustered index using the DROP_EXISTING option.". If I simply try to delete the index I get the following "An explicit DROP INDEX is not allowed on index 'index name'. It is being used for PRIMARY KEY constraint enforcement.
So do I have to drop the PK constraint now? How does that affect all the tables that have FK relationships to this table?
Thanks
I am trying to index through the columns of MyTable so I can do the same work on all columns. I know how to get the column names from MyTable but when I use @MyColName in the SELECT statement to get MyTable Column 0 Row values I get a table with the column name in each row cell. I can't get the syntax correct to return the value in each cell for that column.
This is a extremely simplified example !!!!!!DECLARE @MyColName nvarchar(30)
--Get the MyTable Column 0 NameSELECT @MyColName = Col_Name(Object_ID('MyTable'), 0)
--Display the MyTable Column 0 Row valuesSELECT @MyColName FROM MyTable --This is the syntax I can not get correct
Can anyone help ?
Thanks
Hi everybody!
I just ran the Database Engine Tuning Advisor on a relative complex query to find out if a new index might help, and in fact it found a combination that should give a performance gain of 94%. Fair enough to try that.
What I wonder about: The index I should create contains 4 columns, the last of them being the Primary Key column of the table, which is also my clustered index for the table. It is an identity integer btw.
I think I remember that ANY index does include the clustered one as lookup into the data, so having it listed to the list of columns will not help. It might at worst add another duplicate 4 bytes to each index entry.
Right? Wrong? Keep the column in the index, or remove it since it is included implicit anyway?
Thanks for suggestions!
Ralf
I'm looking for a query that will return all index names, the table the index is on and the columns in the index...
View 1 Replies View RelatedWhat is the impact on the users to drop an index on a table while in use? I will recreate the index afterwards. The table is used constantly by a three of processes/users at all times.
View 3 Replies View Related
Dear All.
We had Teradata 4700 SMP. We have moved data from TD to MS_SQL SERVER 2003. records are 19.65 Millions.
table is >> Order_Dtl
Columns are:-
Client_ID varchar 10
Order_ID varchar 50
Order_Sub_ID decimal
.....
...
..
.
Pk is (ClientID+OrderId+OrderSubID)
Web Base application or PDA devices use to initiate the order from all over the country. The issue is this table is not Partioned but good HP with 30 GB RAM is installed. this is main table that receive 18,0000 hits or more. All brokers and users are using this table to see the status of their order.
The always search by OrderID, or ClientID or order_SubNo, or enter any two like (Client_ID+Order_Sub_ID) or any combination.
Query takes to much time when ever server receive more querys. some orther indexes are also created on the same table like (OrderDate, OrdCreate Date and Status)
My Question are:-
Q1. IF Person "A" query to DB on Client_ID, then what Index will use ? (If any one do Query on any two combination like Client_ID+Order_ID, So what index will be uesd.? How does MS-SQL SERVER deal with these kind of issues.?
Q2. If i create 3 more indexes on ClientID, ORderID and OrdersubID. will this improve the performance of query.if person "A" search record on orderNo so what index will be used. (Mind it their would be 3 seprate indexes for Each PK columns) and composite-Clustered index is also available.?
Q3. I want to check what indexes has been used? on what search?
Q4. How can i check what table was populated when, or last date of update (DML)?
My Limitation is i Dont Create a Partioned table. I dont have permission to do it.
In Teradata we had more than 4 tb record of CRM data with no issue. i am not new baby in db line but not expert in sql server 2003.
I am thank u to all who read or reply.
Arshad
Manager Database
Esoulconsultancy.com
(Teradata Master)
10g OCP
We have 3 maintenance jobs configured in this particular DB instance:
Daily backup of system database - SubPlan1 (Check Database Integrity Task --> Rebuild Index Task-->Backup Database Task)Daily backup of user databases - Five subplans for each task : (Check DB integrity --> Rebuild Index -->Backup User Database, Backup Log -->Cleanup History)Weekly maintenance - SubPlan1 (Check Database integrity job (system+user DB) + rebuild index job (system+user DB) )
PROBLEM: I just noticed that the User DB Rebuild Index task has been running since the 03/04 and the Weekly maintenance plan - subplan1 since the 12/04.
Which job is "safe" to stop without impacting the database?
Hi everyone,
When we create a clustered index firstly, and then is it advantageous to create another index which is nonclustered ??
In my opinion, yes it is. Because, since we use clustered index first, our rows are sorted and so while using nonclustered index on this data file, finding adress of the record on this sorted data is really easier than finding adress of the record on unsorted data, is not it ??
Thanks
I have a clustered index that consists of 3 int columns in this order: DateKey, LocationKey, ItemKey (there are many other columns in this data warehouse table such as quantities, prices, etc.).
Now I want to add a non-clustered index on just one of the other columns, say LocationKey, like this:
CREATE INDEX IX_test on TableName (LocationKey)
I understand that the clustered index keys will also be added as key columns to any NC indexes. So, in this case the NC index will also get the other two columns from the clustered index added as key columns. But, in what order will they be added?
Will the resulting index keys on this new NC index effectively be:
LocationKey, DateKey, ItemKey
OR
LocationKey, ItemKey, DateKey
Do the clustering keys get added to a NC index in the same order as they are defined in the clustered index?
Quick question about the primary purpose of Full Text Index vs. Clustered Index.
The Full Text Index has the purpose of being accessible outside of the database so users can query the tables and columns it needs while being linked to other databases and tables within the SQL Server instance.
Is the Full Text Index similar to the global variable in programming where the scope lies outside of the tables and database itself?
I understand the clustered index is created for each table and most likely accessed within the user schema who have access to the database.
Is this correct?
I am kind of confused on why you would use full text index as opposed to clustered index.
Thank you
Goldmember
The Delete-Insert update happens for key columns of Indexes and that makes sense.
But I am confused that why Delete-Insert update happens for Included columns of nonclustered indexes, where I expected them to be InPlace updates ???
Hello I want to learn disparity clustered index or nonclustered index and in queries which one run better.
example
select * from orders where orderID=5
to this query clustered or nonclustered
thanks
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!
What does an index add to the performance?
Why do we use Clustered Index and Non-clustered Index?
thanks