At managing index SQL Server 6.5, there is distribution button. I have a database on production server, one of the table has 20 indexes. When I press the Distribution button, it reveals that most of the indexes have very poor selection of index, from 30% to 99%. There are 6 of them are very good. Based on this statistics, do you think I should remove these indexes? As the book says, if the statistics is higher than 5%, the optimizer will not use index but do a table scan. Removing those index should not affect the performance, is that right?
Your suggestion is very appreciated.
I have an index that shows distribution statistics of 98.20%, which is very poor. I set show query plan and show statis I/O on. This table has 1113675 rows of data.
************* select orderID, custId, intertcsi from tblorders where intertcsi = '2815'
STEP 1 The type of query is SELECT FROM TABLE tblorders Nested iteration Index : indxInterTCSI orderID custId intertcsi ----------- ----------- --------- 1015245 1011313 2815 2556392 2556392 2815 ....
Table: tblOrders scan count 1, logical reads: 104, physical reads: 58, read ahead reads: 0 *************** Then I use the same select statement to force a table scan:
select orderID, custId, intertcsi from tblorders (index=0) where intertcsi = '2815'
STEP 1 The type of query is SELECT FROM TABLE tblorders Nested iteration Table Scan orderID custId intertcsi ----------- ----------- --------- 60472 61084 2815 102184 102333 2815 ... Table: tblOrders scan count 1, logical reads: 110795, physical reads: 6891, read ahead reads: 103980
When the index is not provided, the logical reads and physical reads increased dramatically. Does this tell me that I should keep that index though it is a poor selection? Is that because a huge table like this make the optimizer use the index. The query without using index takes longer time to run. Any idea or comment would be very appreciated.
I have been asked to create a report for one of our clients. The report is pretty basic but I am concerned about the overheads with my planned approach.The report is at a table and field grain to include values for:
* Min column value * Max column value * Number of discrete values * Number of populated values (not NULL)
My current plan is to have a cursor over a limited view of sys.tables and sys.columns that will run a dynamic SQL query to import the results into a table that I can then output.There must be a better way of doing this and I don't have access to any DQS services.
What are some ways to analyze index coverage and usage? I have a 18 GB database, half is data, other half is indexes and I want to cut down that number as much as I can without affecting performance. Thanks
I have been monitoring some indexes on a table with a lot of inserts, no updates and no deletes. I was wanting to determine when to update the statistics on the index. Does anyone know what would be a good target range for the density when you run the dbcc show_statistics?
I was wondering how often you should reindex. By looking at dbcc showcontig and statistics I see that I am heavily fragmented and scan density is between 10-30% on my important indexes. I'm thinking of scheduling this to be done nightly. nay help is much appreciated.
I have a question regarding updating statistics for a primary key.
Background: An update statistics with fullscan is sometimes taking 30 minutes - the table is 80 million rows, with only 4 columns. The table is truncated, and then 80 million rows inserted all in one go.
Now why the update stats is taking that long is another question (I have no idea - any thoughts?), but my question is; Since you can't disable the "not automatically recompute statistics" option for a primary key, and you would think it would be imperitive for the stats to be kept up to date for a PK for inserts.... does this mean the stats would be kept up to date? and an update stat with fullscan isn't required?
I ran the DBCC SHOW_STATISTICS command for all of my indexes; I was told that high density numbers are bad, low numbers good. I have some questions about my results, though; I'm not sure how to interpret them.
Of 48 indexes, 14 have a density of 0. Does this mean that the indexes are not selective enough? Does it mean they're garbage and I should toss them?
6 have a density of NULL. They are all primary keys. I suppose this just means that they're never used because these tables are rarely queried. Would this assumption be correct?
13 have a density of 1. I have no idea what this means.
The others have densities ranging from 0.01210491 to 0.5841165. I was told that the lower this number is, the more selective and thus more useful an index is. I think 0.5841165 is too high a number. Would this be correct?
Is it neccessary to schedule a update statistics on index in sql server 2005 on daily basis Is it neccessary to schedule a rebuild index on index in sql server 2005 on daily basis
Is there any way to determine index usage statistics for a given table? For examle, I have a table, with three indices. I need to know how many times each index was used. Is it possible?
And second part of question: I need to know, which user overloads my base with their giantic queries. Is there any way to determine, how many system resources each of user's sessions uses?
We have a 20 GB database and reorganize indexes and update statistics maintainance takes about 4 hours and the log files grows out of control what is a serious problem since it can not be truncated (database mirroring).
We have implemented a very small reporting database which has a main table that started off small and has now grown to around half a million rows. Initially, there were no indexes on the table apart from a clustered index, but as the data has grown, performance has dropped and so we have added a number of indexes. This has resolved the performance issues.
Before creating the indexes SQL Server had auto created a number of statistic objects (_WA_Sys_000... etc). After creating the indexes, new statistic objects where created for the new indexes. In some cases, there are duplicate statistics (auto and index) for the same columns.Should I go through and drop the duplicate auto statistics? Will having duplicates cause issues at all?
At one of your client sides we have configured Always on with synchronous mode.Also we have schedule rebuild index and update statistics job which runs in night every alternate day. the issue is there are more then 100 sleeping queries which is blocking update statistics job.
I have to stop update statistics job manually once i come to office manually.
Once I have killed blocking sleeping query but then other sleeping query blocked it and so on.
I am really puzzled by an apparent difference between table index key column order and its statistics order. I was under understanding that index statistics mirror index definition. However, in my db 2470 index ordinal definitions match statistics definition but 66 do not. I also can reproduce such discrepancy in 2008 R2, 2012 and 2014.
As per definition,
stats_column_id int
1-based ordinal within set of stats columns
This script duplicates this for me.
BEGIN TRAN GO use tempdb GO CREATE TABLE [dbo].[ItemProperties]( [itmID] [int] NOT NULL, [cpID] [smallint] NOT NULL, [ipuID] [tinyint] NOT NULL,
[Code] ....
The result I get is this:
object_id      stats_name                                     stats_column_list 1525580473 PK_ItemProperties_itmID_ipuID_cpID itmID, cpID, ipuID,
and
object_id      index_name                                     index_column_list 1525580473 PK_ItemProperties_itmID_ipuID_cpID itmID, ipuID, cpID,
Also a query I used to discover this in my db is:
WITH stat AS ( SELECT s.object_id ,s.name as stats_name ,( SELECT c.name + ', ' as [data()] FROM sys.stats_columns as sc
On SQL Server 2005 SP2 for Publisher and Distributor on the same instance, my old snapshots are not being cleaned up.
The following error is in the agent history:
Executed as user: DomainMyUser. Could not remove directory '\vmsql01ReplDatauncPublication_TRANSACTIONAL20070702104416'. Check the security context of xp_cmdshell and close other processes that may be accessing the directory. [SQLSTATE 42000] (Error 20015). The step failed.
xp_cmdshell is enabled and I can run commands like :
exec master.dbo.xp_cmdshell ' md c:TestFolder'
The permissions to the snapshot share and file system are that DomainMyUser has full control.
I have logged into the machine as this user and can remove snapshots so it does not seem to be a permission issue.
On other machines I do not get any errors but the snapshot folder still is not cleaned up.
Hello group.I have an issue, which has bothered me for a while now:I'm wondering why the column statistics, which SQL Server wants me tocreate, if I turn off auto-created statistics, are so important to theoptimizer?Example: from Northwind (with auto create stats off), I do the following:SELECT * FROM Customers WHERE Country = 'Sweden'My query plan show a clustered index scan, which is expected - no indexexists for Country. BUT, the query plan also shows, that the optimizer ismissing a statistic on Country, which tells me, that the optimizer wouldbenefit from knowing this.I cannot see why? (and I've been trying for a while now).If I create the missing statistics, nothing happens in the query plan (andwhy should it?). I could understand it, if the optimizer suggested an indexon Country - this would make sense, but if creating the missing index, queryanalyzer creates the statistics with an empty index, which seems to me to beless than usable.I've been thinking long and hard about this, but haven't been able to reacha conclusion :) It has some relevance to my work, because allowing theoptimizer to create missing statistics limits my options for designingindexes (e.g. covering) for some rather wide tables, so I'm thinking why notturn it off altogether. But I would like to know the consequences - hopesomebody has already delved into this, and knows a good explanation.RgdsJesper
What is the unit of the numbers you get in the Time Statistics-part when running a query in Microsoft SQL Server Management Studio with Client Statistics turned on?
Currently I get mostly 0´s, but if I try and *** up a query on purpose I can get it up to around 30... Is it milliseconds or som made up number based on clockcycles or... ?
I would also like to know if it´s possible to change the precision.
please explain the differences btween this logical & phisicall operations that we can see therir graphical icons in execution plan tab in Management Studio
I am using Full Text Index to index emails stored in BLOB column in a table. Index process parses stored emails, and, if there is one or more files attached to the email these documents get indexed too. In result when I'm querying the full text index for a word or phrase I am getting reference to the email containing the word of phrase if interest if the word was used in the email body OR if it was used in any document attached to the email.
How to distinguish in a Full Text query that the result came from an embedded document rather than from "main" document? Or if that's not possible how to disable indexing of embedded documents?
My goal is either to give a user an option if he or she wants to search emails (email bodies only) OR emails AND documents attached to them, or at least clearly indicate in the returned result the real source where the word or phrase has been found.
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.
My SSIS package is running very slow taking so much time to execute, One task is taking 2hr for inserting 100k records, i have disabled unused index still it is taking time.I am rebuilding/Refreshing indexes and stats once in month if i try to execute on daily basis will it improve my SSIS Package performance?Â
hello friends i have table1 and 200 coulumn of table1 :) i have 647.600 records. i entered my records to table1 with for step to code lines in one day :) i select category1 category2 and category3 with select code but i have just one index.. it is productnumber and it is primarykey..So my select code lines is so slow.. it is 7-9 second.. how can i select in 0.1 second ? Should i create index for category1 and category2 and category3 ? But i dont know create index.. My select code lines is below.. Could you learn me and show me index for it ?? or Could you learn me and show me fast Select code lines and index or etc ??? Also my search code line have a dangerous releated to attaching table1 with hackers :) cheersi send 3 value of treview1 node and childnode and child.childnode to below page.aspx :) Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load If Not Me.IsPostBack Then If Request("TextBox1") IsNot Nothing ThenTextBox1.Text = Request("TextBox1") End If If Request("TextBox2") IsNot Nothing ThenTextBox2.Text = Request("TextBox2") End If If Request("TextBox3") IsNot Nothing ThenTextBox3.Text = Request("TextBox3") End If End If Dim searchword As String If Request("TextBox3") = "" And Request("TextBox2") = "" Then searchword = "Select * from urunlistesi where kategori= '" & Request("TextBox1") & "'" End If If Request("TextBox3") = "" Then searchword = "Select * from urunlistesi where kategori= '" & Request("TextBox1") & "' and kategori1= '" & Request("TextBox2") & "'" End If If Request("TextBox3") <> "" And Request("TextBox2") <> "" And Request("TextBox1") <> "" Then searchword = "Select * from urunlistesi where kategori= '" & Request("TextBox1") & "' and kategori1= '" & Request("TextBox2") & "' and kategori2= '" & Request("TextBox3") & "'" End If SqlDataSource1.SelectCommand = searchword End Sub
I'm running a merge replication on a sql2k machine to 6 sql2k subscribers. Since a few day's only one of the merge agents fail's with the following error:
The merge process could not retrieve generation information at the 'Subscriber'. The index entry for row ID was not found in index ID 3, of table 357576312, in database 'PBB006'.
All DBCC CHECKDB command's return 0 errors :confused: I'm not sure if the table that's referred to in the message is on the distribution side or the subscribers side? A select * from sysobjects where id=357576312 gives different results on both sides . .
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 ??
I am running a transactional replication on two servers. The distribution agent is reporting a timeout, eventhough the distribution database and the replicated database is on the same server.
Folks, We have just finished an application that requires every client PC to have a system DSN that reflects the new datasource. Is there an easier way to distribute this system DSN other than logging on to each pc and creating the datasource?? Thanks!
I'm new to working with replication & I'm just starting to test some implementations. We're still using the beta, v7.00.517. and... basically nothing works, I can't even open any of the replication management features in Enterprise Manager. As soon as I select any item from the replication menu I get:
Error 208: [Microsoft][ODBC SQL Server Driver][SQL Server]Invalid object name 'msdb.dbo.MSdistributiondbs'
It's either:
A: a bug, B: something screwed up in my system databases, or C: I'm missing something really obvious.
I've got replication set up as a publisher subscriber, to basically sync a primary server with a backup server. My distribution log keeps filling up, I've got a perf alert for now to truncate it at 75% full for now, but why does it fill up? it's size is about 1.5 gig My tran log for my database will also not remove about 500mb of data as well, is there any way to see what is going on?
