SQL 2012 :: Cluster Index Fragmentation
Jun 2, 2014We have few tables where we do truncate load or only do insert activities , why do the cluster index get fragmented very often to > 80%?
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SQL 2012 :: Possible Sources Of Fragmentation On Clustered Index
Jan 23, 2015I have a table that has a clustered index that is only the identity column on the table. The table is somewhere around 200K rows and has 3800 pages in the index. We run our index maintenance every other day on this database using Ola's scripts and this index is rebuilt because it is 40-60% fragmented after 2 days. Overall, this isn't really too much of a problem since the index rebuild doesn't take too long, but I am puzzled as to how this index is getting fragmented since the only column in it is the identity.
CREATE TABLE [dbo].[Example](
[ExampleID] [int] IDENTITY(1,1) NOT NULL,
[ExampleCode] [varchar](10) NOT NULL,
[ForeignID] [int] NOT NULL,
[AnotherID] [int] NOT NULL,
[code]...
) ON [PRIMARY]There is nothing strange like updates to the identity happening and while some records are deleted, there has only been about 20,000 in the life of the table (months). Not enough to account for the level of fragmentation that we're seeing on the index.About the only thing I can think of that would cause fragmentation on this index in this scenario are:
1. Page splits caused by starting with a small value in one of the VARCHARs and later inserting a larger value
2. Page splits caused by the NULLABLE column, ExampleDate, starting with NULLs and later updating them to a date.
For #1, I had development check the update scenarios for the varchar columns, especially the varchar(1000) one, and they didn't see it as a common thing where the values would go from small (or empty) to large.
For #2, I checked and found that the only value for that column in the table is NULL so while it always starts as NULL, it never gets updated to anything else.
I've tried looking at sys.dm_db_index_operational_stats and the leaf_update_count is around 300,000, but unless those updates are causing page splits, I don't see how they would contribute to fragmentation.
Index Fragmentation In AX Dynamics 2012 Database
Dec 17, 2014I've noticed that indexes in my AX 2012 database get very fragmented very quickly. Is this normal and that I should just defragment them regularly or is there a possible issue here that needs investigated?
View 6 Replies View RelatedIndex Fragmentation
Jun 22, 2008What functions of tools do you use for managing index fragmentation?
DBCC?
I am working through MS Press SQL 2005 book and it mentions the
sys.dm_db_index_physical_stats function? It then give an example of code which is very involved.
Does anybody use this function?
Thanks
Index Fragmentation
May 10, 2007before rebuild index
---------------------
tablenameIndexname
avg_fragmentation_in_percent
Payoff_QuotePK_Payoff_QuoteDetail
83.3333333333333
ALTER INDEX ALL ON Payoff_Quote REBUILD
after issue the above statement result remain same.
Index Fragmentation
Jun 24, 2007Hi
When I run sys.dm_db_index_physical_stats on AdventureWorks.Production.Product, I get an average fragmentaion of 46%, 0%, 25% & 50% on the Indexes.
I run ALTER INDEX ALL ON AdventureWorks.Production.Product
REBUILD WITH (FILLFACTOR = 80, SORT_IN_TEMPDB = ON,
STATISTICS_NORECOMPUTE = ON)
and the index fragmentation does not change...
Why is that?? I have tried refreshing the table and the statistics but why does it look like rebuilding the indexes has done nothing?
Index Fragmentation In The DMV
Sep 25, 2007I have a nice script that will look at the index fragmentation by using the DMV (sys.dm_db_index_physical_stats) and if its above a specificed threshhold, it will rebuild or reorg the index.
What I have noticed is that even after reorging and/or rebuilding the index, the fragmentation percent in the DMV does not change for some indexes. Other indexes are updated just fine.
Is this a result of updating statistics? Why would the fragmentation change for some indexes and not others? Why does it seem no matter how much rebuilding or reorging is done, the fragmentation percent for some indexes does not change?
- Eric
Index Showing Fragmentation
May 11, 2015We have nightly job running to reorg all in one of our prod database. But the index on one of the table fragmenting quickly by the morning showing 90% fragmentation.
View 9 Replies View RelatedIndex Fragmentation Issue
Feb 9, 2008
Hi,
It is natural that index gets fragment overtime. But I would like to know how you do the reindexing or defragment when your database table is big and you cannot afford the time to rebuild them. Thanks.
Index Fragmentation On SQL 2000
Nov 8, 2007I have several databases in which our indexes have not been rebuilt/reorganized. I have worked primarily on SQL 2005 but with 2000 I am not familiar with Logical vs Extent fragmentation. And on the 2000 server there is high Logical Fragmentation (1000+%). With me rebuilding the indexes on the 2000 server databases, will this reduce performance or halt functionality of the servers while this process is running???
View 6 Replies View RelatedIndex Fragmentation Strategy For VLDB
Nov 20, 2007I need to manage the problem of negative performance implications when I fragment a 1TB+ DB. I want to perform Index Reorganization if fragmentation is no higher than 30%, and Index Rebuild if the fragmentation exceeds 30%.
Firstly can anyone recommend a script which uses sys.dm_db_index_physical_stats system to ascertain the
fragmentation level. Secondly, is there a technique I can employ to prevent the ONLINE operation completely killing performance on 27/4 production system?
ALTER INDEX REORGANIZE/REBUILD WITH (ONLINE=ON)
Rebuild Does Not Appear To Change % Index Fragmentation
Apr 23, 2007I have been testing methods to maintain indexes in a SQL Server 2005 database which has been migrated from SQL Server 2000. The compatibility level is still set to 80. I used the query below to inspect the degree of fragmentation amongst other things.
SELECT a.index_id
, name
, database_id
, avg_fragmentation_in_percent
,index_type_desc
,fragment_count
,page_count
FROM sys.dm_db_index_physical_stats (NULL, NULL, NULL, NULL, 'DETAILED') AS a
JOIN sys.indexes AS b ON a.object_id = b.object_id AND a.index_id = b.index_id
Some of the indexes in the database had a high degree of fragmentation based on the avg_fragmentation_in_percent value. I tried drop+create, rebuild and reorganise commands on those indexes. Predictably, drop + create was the most effective, but even that did not always reduce fragmentation much. Sometimes the fragmentation was the same no matter what method I used. Other times drop+create helped, rebuild made it worse.
What is going on?
Total Fragmentation On Index Doesn't Drop
Sep 17, 2007I have a non-clustered index on a table. If I rebuild or reorganize it in SQL 2005, the total fragmentation percent reported by properties/fragmentation on the index stays at 33%.
Why doesn't the fragmentation go to 0% ?
If I totally drop/create the index, starts even higher, but beorg or rebuild simply goes to 33%. This even if using with use temp db for sort option.
Reorganizing/Rebuilding Index Results In More Fragmentation?
Dec 11, 2007I have been reworking my index maintenance jobs from my old SQL 2000 table and view references to the DMV's and System Tables in SQL 2005, and I noted that some of my indexes end up being more fragmented after a reorganization and or rebuild. That doesn't make much sense to me at all. The code I am executing is:
Code Block
print ' '
print '************* Beginning Index Updates for '+db_name()+' *************'
print ' '
DECLARE @tablename varchar(250),
@indexname varchar(250),
@fragpcnt decimal(18,1),
@indexid int,
@dbID int
-- Determine DB ID
SELECT @dbID = DB_ID()
DECLARE tnames_cursor CURSOR FOR
SELECT b.name, c.name, a.avg_fragmentation_in_percent, a.index_id
FROM sys.dm_db_index_physical_stats (@dbID, NULL, NULL, NULL, NULL) a
JOIN sys.indexes b ON a.object_id = b.object_id
AND a.index_id = b.index_id
JOIN Sys.objects c ON b.object_id = c.object_id
WHERE a.index_id > 0
ORDER by a.page_count DESC
OPEN tnames_cursor
FETCH NEXT FROM tnames_cursor INTO @indexname, @tablename, @fragpcnt, @indexid
WHILE (@@fetch_status = 0)
BEGIN
-- Declare and determine the tablename ID
declare @tablenameID int
select @tablenameID = object_id(@tablename)
IF @fragpcnt > 30
BEGIN
EXEC('ALTER INDEX ['+@indexname+'] ON ['+@tablename+'] REBUILD')
PRINT '***************************************************'
PRINT 'Index '+@indexname+' was rebuilt.'
PRINT 'Original framentation Percent: ' + convert(varchar, @fragpcnt) + '%'
SELECT @fragpcnt = avg_fragmentation_in_percent
FROM sys.dm_db_index_physical_stats (@dbID, @tablenameID, @indexid, NULL, NULL) a
JOIN sys.indexes b ON a.object_id = b.object_id
AND a.index_id = b.index_id
JOIN Sys.objects c ON b.object_id = c.object_id
PRINT 'Post Rebuild fragmentation Percent: ' + convert(varchar, @fragpcnt) + '%'
PRINT ''
END
ELSE IF @fragpcnt BETWEEN 5 AND 30
BEGIN
EXEC('ALTER INDEX ['+@indexname+'] ON ['+@tablename+'] REORGANIZE')
PRINT '***************************************************'
PRINT 'Index '+@indexname+' was Reorganized.'
PRINT 'Original framentation Percent: ' + convert(varchar, @fragpcnt) + '%'
SELECT @fragpcnt = avg_fragmentation_in_percent
FROM sys.dm_db_index_physical_stats (@dbID, @tablenameID, @indexid, NULL, NULL) a
JOIN sys.indexes b ON a.object_id = b.object_id
AND a.index_id = b.index_id
JOIN Sys.objects c ON b.object_id = c.object_id
PRINT 'Post Reorganization fragmentation Percent: ' + convert(varchar, @fragpcnt) + '%'
PRINT ''
END
ELSE
BEGIN
PRINT '***************************************************'
PRINT 'Index '+@indexname+' was left alone.'
PRINT 'Original framentation Percent: ' + convert(varchar, @fragpcnt) + '%'
PRINT ''
END
FETCH NEXT FROM tnames_cursor INTO @indexname, @tablename, @fragpcnt, @indexid
END
print ' '
print '************* NO MORE TABLES TO INDEX *************'
PRINT 'All indexes for the '+db_name()+' database have been updated.'
print ' '
DEALLOCATE tnames_cursor
Below are some snipits of the output:
***************************************************
Index _dta_index_wuci_history_8_1123587141__K2_K5 was rebuilt.
Original framentation Percent: 58.3%
Post Rebuild fragmentation Percent: 58.3%
***************************************************
Index PK__batchjob__776C5C84 was left alone.
Original framentation Percent: 0.0%
***************************************************
Index PK__ContactWebDetail__116A8EFB was rebuilt.
Original framentation Percent: 44.4%
Post Rebuild fragmentation Percent: 77.8%
***************************************************
Index PK__managed_object_s__5DCAEF64 was left alone.
Original framentation Percent: 0.0%
***************************************************
Index kb_IX_kb_scope_scope_role was rebuilt.
Original framentation Percent: 75.0%
Post Rebuild fragmentation Percent: 87.5%
***************************************************
Index PK__query__09A971A2 was left alone.
Original framentation Percent: 0.0%
***************************************************
Index PK__email_message__38996AB5 was rebuilt.
Original framentation Percent: 85.7%
Post Rebuild fragmentation Percent: 0.0%
***************************************************
If the index begins with PK, then it is the primary key index which is generally the clustered index on the table, but not always. If it has an IX on it, it is generally a non-clustered index on the table, but again not always. In the case of the above, the PK is a clustered index, and the IX is a non-clustered index.
Anyone have any ideas why this is functioning in this manner?
Thanks,
Jon
Transact SQL :: Index Fragmentation For Identity Column?
Jun 26, 2015In my database all columns have Identity Value as a PK.
Now today I check Index Fragmentation I saw that many cluster and Non cluster Index are avg.Fragmentation is around 99 % I thought that in Identity column record is always inserted at bottom so there is no fill factor assigned to it.
So in this case Do I need to set Fill factor for Cluster and Non Cluster Index?
If Yes Then For PK How much - 95 % or what? and same for Non cluster or It should around 85 to 90
PK Still Shows Fragmentation After ALTER INDEX.. REBUILD
Sep 4, 2007I am using sys.dm_db_index_physical_stats to identify indexes that need to be rebuilt based on a fragmentation limit. Once identified, I execute and ALTER INDEX... REBUILD on the index. If the index is clustered, only that index gets rebuilt for the table. After all the indexes are complete, I receive a report on the indexes that were rebuilt in the databases and what level of fragmentation the index was at before rebuilt. After checking these indexes, I still see that all the Primary Key indexes are still at the same fragmentation level. I run the process again and it does not change. I updated table usage and also ran update statistics after running the rebuild again, but the fragmentation does not change. Why can��t these PK Clustered indexes be rebuilt as expected? Do I need to drop and recreate the PK before this fragmentation changes?
View 7 Replies View RelatedIndex Fragmentation LogicalFragmentation -how Bad Is Bad - Silly Question Alter
Mar 10, 2007I thought I would delve into index fragmentation and I found somegreat sql from many posters (thanks Erland!).My question is how bad is bad? I know this is very subjective.Some scripts I found would reindex if the LogicalFragmenation is over30%.I have some tables that are 98% (I'm guessing really bad). I know itall depends..more as a learning point: I found a table that had over 30%logicalfragmentation, I dropped the indexes, created then ran thescript that used type code segment:'DBCC SHOWCONTIG(' + @TableName + ') WITH TABLERESULTS, ALL_INDEXES,NO_INFOMSGS')In one case, the indexes for the table dropped below 30%, in anothercase the index was still fragmented ever after I dropped and re-created index.SQL Server 2005 x64 SP2This is the script I am running (I found this in another thread thatErland posted):SET NOCOUNT ONUSE ds_v6_sourceDECLARE @TableName VARCHAR(100)-- Create a table to hold the results of DBCC SHOWCONTIGIF OBJECT_ID('Tempdb.dbo.#Contig') IS NOT NULLDROP TABLE #ContigCREATE TABLE #Contig ([ObjectName] VARCHAR(100), [ObjectId] INT,[IndexName]VARCHAR(200),[IndexId] INT, [Level] INT, [Pages] INT , [Rows] INT ,[MinimumRecordSize] INT,[MaximumRecordSize] INT , [AverageRecordSize] INT,[ForwardedRecords] INT ,[Extents] INT, [ExtentSwitches] INT, [AverageFreeBytes]NUMERIC(6,2),[AveragePageDensity] NUMERIC(6,2), [ScanDensity]NUMERIC(6,2) ,[BestCount] INT ,[ActualCount] INT , [LogicalFragmentation] NUMERIC(6,2) ,[ExtentFragmentation] NUMERIC(6,2) )DECLARE curTables CURSOR STATIC LOCALFORSELECT Table_NameFROM Information_Schema.TablesWHERE Table_Type = 'BASE TABLE'OPEN curTablesFETCH NEXT FROM curTables INTO @TableNameSET @TableName = RTRIM(@TableName)WHILE @@FETCH_STATUS = 0BEGININSERT INTO #Contig EXEC('DBCC SHOWCONTIG(' + @TableName + ') WITHTABLERESULTS, ALL_INDEXES, NO_INFOMSGS')FETCH NEXT FROM curTables INTO @TableNameENDCLOSE curTablesDEALLOCATE curTables
View 8 Replies View RelatedExtent Fragmentation Still High After Index Drop/create
Jul 20, 2005hello everyone,we dropped the clustered & nonclustered indeces on a table, thenrebuilt them. logical fragmentation is near zero, but extentfragmentation is about 40%. how can this be if the indeces are brandnew?
View 2 Replies View RelatedSQL Server Admin 2014 :: Reducing Index Fragmentation During Inserts
Apr 26, 2015We have a database with a table that contains around 180m records. Each day a further 70k are inserted. No records are ever deleted as this table is used for archiving only.Users are required to perform SELECTs on this table constantly but due to the high number of INSERTs the indexes become very fragmented very quickly. My aim is to avoid daily rebuilds of the indexes which is what our software house is telling us we have to do.
This is the DDL for the table:
CREATE TABLE [dbo].[Inventory](
[EAN] [bigint] NOT NULL,
[Day] [smalldatetime] NOT NULL,
[State] [int] NOT NULL,
[Quantity] [int] NULL,
[StockValue] [float] NULL,
CONSTRAINT [PK_Inventory] PRIMARY KEY CLUSTERED
[code]...
There are also three clustered Indexes on this table each referencing a single column. The problem from my side is that I cannot understand why the three columns in a primary key would also be configured as non-clustered indexes.My solution would be one of the following:
1. Accept the tables are going to be fragmented and require a daily rebuild (don't like this one!)
2. Partition the table
3. Remove the non-clustered Indexes and let the clustered index for the primary key do the work.
Script To Change Cluster Index To Non Cluster
May 20, 2003Hi all,
We have many tables which have cluster index on column with datatype 'Char(200)'.
Does anyone have script to change cluster index to noncluster for all user tables which have clustered index on a column with 'char(200)' datatype.
Thanks,
Deepak
Transact SQL :: Difference Between Cluster And Non-cluster Index
Jul 26, 2015Wanted to know about difference between cluster and non cluster index with example.
When to use cluster index and non cluster index .
SQL 2012 :: Advanced Cluster Preparation For New Instance On Existing Cluster
Apr 10, 2014I ran the Advanced cluster preparation for a new sql instance on an existing cluster.
Slq Server 2012.
After is completed, it was successful, I realized I specified the wrong Instance Root directory.
Is it possible to remove what the preparation installed? Or is it possible to change the root directory?
SQL 2012 :: Server Cluster Without Windows Failover Cluster
Feb 18, 2014I´ve been reading that SQL Server 2012 Always On is dependent on having a Windows Failover Cluster setup. Is that correct ?
View 6 Replies View RelatedSQL 2012 :: Full Text Index How To Make It NOT To Index Embedded Or Attached Documents
Sep 30, 2015I 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.
To Cluster Index Or Not
Mar 30, 2001I have inherited a db with no clustered indexes, but composite indexes on each table. The DB has about 500 tables(1-5 gig when fully loaded), but on a given session a user might only insert 1 or 2 records in 6-7 of the tables, with about 20-30 current users 8-5PM. THe DB is kinda of a mix between low-end OLTP and DSS. For space and performance I was going to drop the existing indexes and replace them with clustered indexes. Any opinions or gotchas appreciated
View 1 Replies View RelatedPrimary Key With Cluster Index
Oct 9, 2007Hi All,
One of my client having 1 million(nearly) records in a table.
I defined the table as below
1) Created table with one col(we can name it as "ID") having IDENTITY
2) Using "alter table", I created CLUSTERED PRIMARY KEY Constraint on Same field (ID)
3) The Primary key having 2 ref with another 2 tables
Now the issue is when we create or define a primary key (With Clustered Option) automatically cluster Index will be created on defined table
As such table having huge data whenever any updation or insertion against that particular table taking huge amount of time, because the cluster Index trying re-paging whole data. Because of re-paging each and every time "Transaction Log also growing in huge" (database is in full recovery mode and client wants in same mode only)
Data partitioning not posible because whole data related and current live data
I tried following options with vain
1) To Clear transaction log I suggested to take regular log backup's
2) I tried to drop cluster index and tried to implement non clustered index
Drop and re-create index is take taking huge amount of time
Even in this process I have to Re_Index remaining Index's also
Pls give me any other solution or suggestion in this regard
with Thanks & Regards
Bhaskara
SQL 2012 :: Clustered Index Key Order In NC Index
Mar 5, 2015I 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?
SQL Server 2008 :: Cluster Index Key Value
Sep 24, 2015I have a table which has cluster index on col1 column. If i insert 10 into my table what would be cluster index key value?Is it going to be 10 as well? How do i get cluster index key value?
View 5 Replies View RelatedCluster Index On 2 Columns Order
May 29, 2007
I have 2 columns in a table namely ColA and ColB.all DML operations are through views n every view has
Where clause i.e where ColA=�?�? with check option .
All most all my DML queries are using where clause on ColB
Where ColB=�?�?
Now my question is I have a clusted index on both ColA and ColB.in which order I have to create cluster index .
i.e ColA ASC,ColB ASC or ColB ASC,ColA ASC.
Is there any performance gain we can achieve with their order
SQL Server Admin 2014 :: Deadlock Because Of Non-Cluster Index
Jun 11, 2015Dead lock is coming in select query in application because of index. It is identified after enabling trace in database and identified by reading deadlock xml file. After index removal, deadlock is not coming in same query. But it is affecting query's performance slightly. Is it correct way to remove index if dead lock is coming because of index?
View 3 Replies View RelatedWhat Will Happen When A New Row Inserted In A Table Where A Cluster Index Is Defined
Sep 7, 2007As we all know that cluster index physically sort the table. Now what will happen if I insert a new row in the table which voilating the sort rule of table.
Will it inserte at the end of table or table is reordered as cluster index always keep table in physically sorted . Please cleaar my doubt.
SQL 2012 :: Failover Cluster Using Virtual Box
Mar 29, 2014I have virtualbox installed on my notebook. For testing purpose, is it possible to setup SQL Server Fail-Over cluster using virtual box? I don't have a shared storage. How can I simulate that?
View 1 Replies View RelatedSQL 2012 :: How To Create Failover Cluster Using VMs
May 5, 2014How to create a SQL 2012 Failover cluster using VMs?
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