When do we should not use the indexes?
In Inserts? In Updates? in Deletes?
If i have a massive delete like:
delete from table1 where column1='X' (2 million rows) should i have the index enabled or not?
Whats the best option? To disable indexes on massive inserts and then rebuild or to delete and recreate?
Best Regards
I'm working to improve performance on a database I've inherited, and there are several thousand indexes. I've got a list of ones which should definitely exist within the database, and I'm looking to strip out all the others and start fresh, though this list is still quite large (1000 or so).
Is there a way I can remove all the indexes that are not in my list without too much trouble? I.e. without having to manually go through them all individually. The list is currently in a csv file.
I'm looking to either automate the removal of indexes not in the list, or possibly to generate the Create statements for the indexes on the list and simply remove all indexes and then run these statements.
As an aside, when trying to list all indexes in the database, I've found various scripts to do this, but found they all seem to produce differing results. What is the best script to list all indexes?
So I'm reading http://www.sql-server-performance.com/tips/clustered_indexes_p2.aspx and I come across this:
When selecting a column to base your clustered index on, try to avoid columns that are frequently updated. Every time that a column used for a clustered index is modified, all of the non-clustered indexes must also be updated, creating additional overhead. [6.5, 7.0, 2000, 2005] Updated 3-5-2004
Does this mean if I have say a table called Item with a clustered index on a column in it called itemaddeddate, and several non-clustered indexes associated with that table, that if a record gets modified and it's itemaddeddate value changes, that ALL my indexes on that table will get rebuilt? Or is it referring to the table structure changing?
If so does this "pseudocode" example also cause this to occur:
sqlstring="select * from item where itemid=12345"
rs.open sqlstring, etc, etc, etc
rs.Fields("ItemName")="My New Item Name"
rs.Fields("ItemPrice")=1.00
rs.Update
Note I didn't explicitly change the value of rs.fields("ItemAddedDate")...does rs.Fields("ItemAddedDate")=rs.Fields("ItemAddedDate") occur implicitly, which would force the rebuild of all the non-clustered indexes?
I have a requirement to only rebuild the Clustered Indexes in the table ignoring the non clustered indexes as those are taken care of by the Clustered indexes.
In order to do that, I have taken the records based on the fragmentation %.
But unable to come up with a logic to only consider rebuilding the clustered indexes in the table.
create table #fragmentation
(
FragIndexId BigInt Identity(1,1),
--IDENTITY(int, 1, 1) AS FragIndexId,
DBNAME nvarchar(4000),
TableName nvarchar(4000),
[Code] ....
What is the difference please?
View 1 Replies View RelatedSir,
1. How do I call the indexes created in SQL server for a table from Front end VB programming ?
2. How can I use SEEK command with ADODB control ?
Please give me some tips & samples
Sundar Raman
Does anyone have the idea why the Indexes with _WA.....(like _WA_Sys_au_fname_07020F21) gets created.I don't how this index got created. I did not create this Index.
My Question is does the system creates these indexes or something else does this.
Thanks
Chak
Is there a way to tell how many indexes exist for an entire database, all I'm looking is for a count or generating a report list.
any help would be appreciated, thank you
At present I have been assigned to create indexes to retrieve the information fast, from the table. The existing table doesn’t have primary key, foreign key and unique constraints but I found to many default indexes already created by the system. I would like to know how this happened? Please inform how to delete these default indexes. Further, inform me other possible ways for the faster retrieval in SQL sever 7.0, if there are any.
I would appreciate if you send me a step by step explanations for the above problems.
Thanks a lot
I have run into a snag on my development server. Queries that are selecting data based on indexed fields in a where clause are using the wrong indexes. They are arbitrarily using the clustered index which isn't in the select at all and causing big performance problems. I can run the same statements on my production server and it runs based on the proper indexes. I used query execution plans to determine that this was infact the case.
I run DBCC Checkdb everynight and it comes back with no errors. I also rebuild the indexes. We also don't receive any other errors inputting or updating data. This sounds like corruption to me but if it's something else I don't want to spend the night restoring from production if there is another reason.
Has anyone encountered this before? Any ideas?
Appreciate it, K.
Is there any way for me to find out when last indexes have been used so that the one I don't need can be dropped.And also the one's that are of no use at all.
I need this as i am trying to dump all duplicated indexe . i know i can do this in ver 7
thanks
when executed sp_help tablename, I get lot of statistics and indexes like the following. Can anyone please tell me how it is generated automatically. as far i know statistics are generated only for primary keys. Can you please tell me what is clustered , hypothetical and the indexes starting with _WA supposed to be. Also there are lot of duplicate stats. Is it Ok to deletes those.
_WA_Sys_is_platinum_0A9D95DB
_WA_Sys_active_0A9D95DB nonclustered, statistics, auto create located on PRIMARY Active
hind_c_33_15 nonclustered, statistics located on
hind_c_37_1 clustered, hypothetical located
Thanks
Raj
Is there a way T-SQL script can find out all indexes built on a set of tables, drop them and periodically ( quarterly as an example ) re-build them ?
Thanks in advance for help.
Ivan
How do you find out indexes ( with column names info ) on a table ?
Thanks in advance.
Ivan
I am on SQL 6.5.
I have a question about speed and indexes. I have a static table (no updates except once a year). I want to be able to search data quickly on one column or many columns. I have created nonclustered indexes on each of the columns I search by. Is there anything else I can do to speed up my queries? Unfortunately all the searches involve using the like operator. I have even broken my table down into 2 smaller tables (Table A ~ 3 million rows, Table B 8 million rows).
All suggestions will be appreciated.
Thanks,
Eric
We have to interduce a new naming convention for the indexes currently available in the user databases.
We also have to drop all the old indexes available in about 250 tables and recreate them all acording to the naming convention we are coming up with.
Can any body suggest any idea.
I thank you guys in advance for your considaration.
hi.
there 2 different queries
1
[MYSQL].... where Cat=@CatID and Date=@Date[/MYSQL]
2
[MYSQL]... where Cat=@CatID and Date=@Date and Salesman=@SID[/MYSQL]
these queries are often used.
my question is about indexes.
should I use two different indexes?
index 1 : Cat,Date
index 2 : Cat,Date,Salesman
or only index 2 is enough ?
I need to alphabetize PART of a union all query, and was told that this may be accomplished with an index. I tried joining two views, but it does not work! I have NO experience with indexes and need some help.
Here is my code:
Select id, country from countries where id = 6 union all Select id, country from countries where id <> 6
I want the country with id 6 (USA) to be the default on a drop down list, then all the other countries listed after it in alphabetical order. Can you do this with an index? If so, how do I proceed?
Thanks!
Ronna
Hi all,
I want to know all indexes in database.
What do I do to get them?
Thanks in advanced,
Thi Nguyen
We recently updated some of the databases from MS Access 2000 to SQL Server 2000. In Access we had columns which were set to Indexed No Duplicates, these were not Primary key fields. Is this possible to set some indexes to prevent duplicates in SQL Server without creating performance issues?
Miranda
Do you have to take the DB offline to create or run indexes in SQL Server 2000??
View 2 Replies View RelatedQ1
The table i have stores max 2000 records. Not sure if i neeed a clustered index for this few records. I guess not.
Q2
For the same table as above. How do you create primary keys if there is not unique records.
Do i create a new column? like newColumnID identity? and create a primary key on this new column? Ok even if i create this newcolumn. I don't think it will improve the retrieving speed cause i'm not selecting this column.
Opinions, ideas?
i am running a stored procedure which has got clustered indexes created after creating table and data is inserted into it after creating clustered indexes. The tables which are meant in this sp is temporary tables and how to gain the performance of a query
View 2 Replies View RelatedI've created indexes for the queries below running select getdate() before and after the query to determine the time. I'm curioius as to how sql server determines and decides how and when to use the indexes for the queries and how the run times of these queries compare. I'm also curious to know what kind of difference there would be on the last two queries as the only difference is the values.
For the last two queries I don't think there would be a difference but hoping that someone would know.
Below are my results:
select count(distinct CustomerID)
from Orders
where Status = 5
SELECT getdate()
go
Create Index Orders_Index On Orders(customerID)
go
SELECT getdate()
select sum(TotalDue)
from Orders
where CustomerID = 11212
select getdate()
go
Create Index Orders_Index On Orders(customerID)
go
select getdate()
select count(distinct AccountNumber)
from Orders
where SalesPersonID = 288
select getdate()
go
Create Index Orders_Index On Orders(salespersonID)
go
select getdate()
select count(distinct AccountNumber)
from Orders
where SalesPersonID = 276
select getdate()
go
Create Index Orders_Index On Orders(salespersonID)
go
select getdate()
where can i find a example on how tobuild a script to reindex all my tablesTksDaveP
View 2 Replies View RelatedI have a very large table (about 200,000 records), but there are only 2 fields in the table only one populated with data. I need to update the 2nd field with the first field's data.
UPDATE Table1
SET field2 = field1
This is taking a really long time to run about 3.5 minutes.
Is this normal? Can I create an index? What can I do to shorten the run time?
Thanks,
Ninel
Aren't all indexes created as separate structures from a table?
Although the index is created against a particular
table, doesn't the index itself exist in the database as a separate,
self-contained structure?
Which index type -- clustered or nonclustered -- logically
sorts the database of a table?
Hi,
I need some help in deciding for the best index design possible for my requirements.
Well basically i have 3 tables (lets call it T1, T2 and T3 ).
T1 is only used like a source...
T2 is a source and destination...
T3 is only a destination table.
Lets suppose all tables have the same columns structure.
In the first phase i insert records from T1 into T2 using lots of different queries filters like this:
WHERE Col1 = x
AND Col2 IN (A and B)
AND Col3 Between Int1 and Int2
AND Col4 = y
Other queries looks the same but diferent column is used in the Col4 place... so it can be Col5, 6 or 7 for example.
In the second phase i do the same but from T2 into T3...
Whats the best index design in this case?
Should i disable indexes in the destination table T2 while i am loading it and the rebuild? This can take alot of time, any other way? Is it best to leave it enabled all the time?
What kind of indexes should i create? Multi Column indexes or single ones for Col1, 2 3 4 5 6.. etc??
Best Regards
i have some confusions with keys and indexes.. plz let me know whether the following are correct..- Every Primary Key is a Clustered Index- A Primary Key cannot exist without a Clustered Index- Every Unique Key is a Non-Clustered Index - Non-Clustered Index is the DEFAULT Index- A table can have only 1 Primary key- A table can have only 1 Clustered Index- A table can have any number of Unique Keys- A table can have any number of Non-Clustered Indexes
Just a quick question, Is it better to build an Indexindicies after creating a new table or after populating the table with the data. Which is quicker? What about statistics? This table is dropped/and then recreated on a weekly basis. It is a reporting database.
Thanks.
Hi!
I was wondering what kind of locks (if any) SQL Server 2000 holds on tables while rebuilding clustered and non-clustered indexes.
Thanks!
We are developing an Access application that will be used to run adhoc reports against a SQL Server table. Selection criteria is entered on a form, a passthru query is built on the fly, and the results are formatted for output via an Access report.
There are 16 different fields on the query form. Two are date fields (from / to), the rest are text. The user is required to supply a date range for the report. They may specify any combination of the remaining query fields.
Examples:
From/To dates, part number, work order number
From/To dates, location, operation, sales order number, operator
What is the best scheme to use for the indexes? One index for each potential query field? Or, a single index that includes ALL query fields? Or, some other combination?
I should also mention that there will be no realtime updates to the table. On a weekly basis, we will import updates from a mainframe extract (dropping the indexes prior to the import, rebuilding them afterwards).
I need to know what indexes are on some particular table, their names, what columns they are on.
The databse is remote & I can't use sp_statistics, only select statement.
Any ideas anyone?