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Questions tagged [fragmentation]

Fragmentation exists when indexes have pages in which the logical ordering, based on the key value, does not match the physical ordering inside the data file.

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Rebuilding Indexes [closed]

I'm working with a db where I have tons of fragmentation issues. I'm rebuilding some of these indexes. Can anyone tell me how come the fragmentation of an index is not 0 after the rebuilding process. ...
2
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1answer
189 views

Table Fragmentation

If I execute the following: SELECT dbschemas.[name] as 'Schema', dbtables.[name] as 'Table', dbindexes.[name] as 'Index', indexstats.alloc_unit_type_desc, indexstats.avg_fragmentation_in_percent as ...
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1answer
218 views

Fragmentation Level for Heaps

I am currently using scripts provided by Mr. Ola Hallengren for executing maintenance job and of-late I have been noticing that there are many tables (heaps) fragmentation level is alarmingly high and ...
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2answers
66 views

Will frequent creation and deletion of TABLE (not indexes) cause fragmentation in database?

Does frequent creation and deletion of physical table in database causes fragmentation? I am frequently creating and deleting database for loading data warehouse load. I am using these table to hold ...
0
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1answer
77 views

MariaDB defragmenting with new option innodb-defragment=1

I try to defragment table using innodb-defragment=1 https://mariadb.com/kb/en/library/defragmenting-innodb-tablespaces/ But it was a bad experience : - locks on table - no a good defragmentation ...
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1answer
62 views

use DBCC SHRINKDATABASE after rebuild / reindex [duplicate]

I have little free disk space. Why shouldn't you use DBCC SHRINKDATABASE (DBName, TRUNCATEONLY) after every rebuild/reindex operation?
3
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2answers
124 views

SQL Server one-to-many and index fragmentation

I'm currently writing code to update an entities child collection (one-to-many relationship), and while thinking about how to write code to determine which entities have been added/removed/modified, I ...
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0answers
17 views

Does rebuilding and reorganizing indexes yield less fruitful results on tables that don't have clustered indexes?

I understand the operations of rebuilding and reorganizing indexes at a high level, but was wondering what they are actually doing on a table that doesn't have a clustered index (i.e. a table stored ...
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3answers
2k views

Table and Index fragmentation

Is there any way to check whether a table or index has been fragmented? How to check if table is fragmented or not? How to check if index is fragmented? I searched Google but didn't get ...
0
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1answer
83 views

Index Maintenance - Reorganize After BIG SQL Server Shrink

I'm planning to execute the below index maintenance created by Ola Hallengren in a 1TB Database. EXECUTE [dbo].[IndexOptimize] @Databases = 'USER_DATABASES', @FragmentationLow = NULL, @...
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0answers
56 views

Fragmentation of indexes with small a database

I'm trying to figure out whether its worth defragging a 2GB mssql database. indexs are above 70% fragmented but queries don't appear to be talking too along. That being said I am having a delay when ...
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2answers
334 views

How to Limit DTU Percentage Consumption for a Given Session in Azure SQL Database?

We have an Azure SQL Database tier S4 (200 DTU), and there is one big table inside When I run a "alter index rebuild..." statement, it takes about 18 mins to complete This particular nonclustered ...
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2answers
76 views

Is Ola Hallengrens Stored Procedure what we need and safe to use [closed]

I stumbled across a stored procedure and wanted to clarify a few things first as I’ve been told it needs “rigorous review before being executed on any server”, and “testing before we run it on a ...
3
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1answer
169 views

Is high index fragmentation an issue on performance

Below is a small sample (top 20ish) from over 8000 indexes in avg_fragmentation_in_percent descending order. Will this cause any performance issues?
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1answer
233 views

Fragmentation in InnoDB tables: dump all data together reduced size, but fragmentation got worse

I have a question about tables and fragmentation in MySQL My starting point is this question: How find and fix fragmented MySQL tables I have a table with 1 million of rows and 128MB of space. This ...
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3answers
109 views

DataBase Performance Issues with Indexes

I'm reviewing a production database with over 400 tables and 658 indexes. I have determined that only 440 of these indexes are being used. Of these, many have fragmentation approaching 100% so I will ...
1
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2answers
198 views

Should I defragment InnoDB table with fixed-length fields?

I am running MariaDB 10.2.13 on Linux (Debian). I am setting up an InnoDB table that will record a lot of data but I will keep only the last one-hour rows. Thus, the number of rows will remain ...
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1answer
246 views

test data to generate high index fragmentation level

I want to test the rebuild and reorganize operations for the indexes in sql server and for that I need to populate the db with test data that generates high fragmentation levels/percentages. Does ...
2
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1answer
74 views

defragment SQL server database

I have deleted some tables on a SQL server. Suddenly the size of the database jumped by 100Gb (whereas the deleted tables were taking 10% of that..). I have read good and bad things about SHRINK ...
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1answer
1k views

Fragmentation in PostgreSQL 9.1

How can I check for fragmentation in PostgreSQL 9.1?
3
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1answer
846 views

Non-Unique Clustered Indexes Administration

I have been recently assigned to administer a database in SQL Server 2016 and I have discovered that there are many tables in the database with Non-Unique Clustered indexes resulting in Non-Clustered ...
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2answers
309 views

Determining what objects SHRINKDATABASE will free space from

First off, yes, shrink is bad. Don't use it, ever. I understand. Unfortunately, it's kind of SOP and I'm not in a position to argue since it's usually a stopgap until we can get a maintenance window ...
0
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1answer
561 views

MSSQL: High number of logical reads when inserting into fragmented heap

I'm inserting a batch of rows - using INSERT INTO tblUploadBanking SELECT FROM ... - into a table, which is a heap and have 3 narrow NC indexes. When I execute the query from SSMS with SET ...
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1answer
923 views

Is there a way to get index fragmentation without using dm_db_index_physical_stats? [duplicate]

I am using SQL Server 2016 SP1 standard edition. The view dm_db_index_physical_stats is very slow on big databases. Even if I specify the 'LIMITED' option. I use the view to get index fragmentation, ...
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0answers
108 views

Does disk fragmentation affect DB performance?

In one of the recent interviews I was asked DB question - There is a DB with ta table having million rows. Over time will it's performance degrade. Why and how? My answer was due to fragmentation (We ...
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2answers
470 views

Online & Offline Index Rebuild

I had this weird case today. Inside a database I had about 50 (1000+ pages, most of them 50000+ pages) tables which had their indexes fragmented above 70% even though I am running a nightly rebuild ...
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2answers
81 views

Are there any (functional or nuanced) differences between rebuilding an index and a full drop/create? If so, what are they?

I have been working on index fragmentation for indexes that are heavily used and causing performance decreases. Our standard job checks fragmentation levels and reorgs if >5% and <30%, and rebuilds ...
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0answers
294 views

Extreme high index fragmentation in MS SQL Server

I have a problem with CLUSTERED INDEX, every one of my table have extemely high total fragmentation, around 92% with having page fullness in the same time at around 99%. So in my understanding pages ...
3
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1answer
1k views

How can I *actually* defragment my InnoDB tables?

After a recommendation by mysqltuner I've run mysqlcheck --optimize --all-databases successfully (all of the tables reported "note : Table does not support optimize, doing recreate + analyze instead" ...
3
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1answer
799 views

Do we have to run auto update statistics after index rebuild?

I want to rebuild one of my indexes because fragmentation has reached 97 percent. I want to know if after I rebuild my index, do I have to update the statistics as well? My auto update statistics ...
0
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1answer
487 views

Distributed database for worldwide LIDAR point cloud [closed]

I have an idea for a project that would build a free worldwide 3D scan of the real world. You may think of it as a high-definition version of OpenStreetMap (OSM) project. The point cloud data would ...
1
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1answer
459 views

Index with high fragmentation percentage

I have a very large table with enormous percentage of index fragmentation( almost 98 % !). Obviously, it needs index rebuild. Main problem is my SQL Server is in Standard edition, thats why I cannot ...
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0answers
20 views

InnoDB: in what scenarios, if any, is it okay to have random insert WRT primary key?

For now let's ignore the benefits of having a surrogate key for business logic reasons. Let's only consider performance (speed and disk usage). CREATE TABLE `person` ( `ssn` bigint(20) unsigned NOT ...
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1answer
163 views

What is Heap Fragmentation sans Indexes?

When you talk about fragmentation in a heap that has no indexes, there can't be logical order fragmentation, so does fragmentation in this instance only refer to non-contiguous pages? Edit: no. Is ...
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2answers
532 views

SQL Server heap tables fragmentation monitoring

As a SQL Server DBA I have maintenance jobs to regularly rebuild/reorganize indexes. Recently, I ask myself about table fragmentation in SQL Server. Then I have read article regarding heap tables and ...
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1answer
94 views

Considerations for performance comparison with a high fragmented heap?

I am planning to perform some performance comparisons for different structures of one and the same table. The table I want to investigate on is a heap having ~ 1Mio rows and 123 columns. Setup: I ...
2
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3answers
512 views

Update statistics more often and stop defragmenting indexes

I have several vendor databases that have most (99%) of the tables clustered on GUIDs. Currently we are rebuilding the tables every weekend. Most tables are 80% or more fragmented by this time. ...
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1answer
8k views

How to lower HEAP Fragmentation in SQL Server?

i recently found out that one heap table had more than 70% fragmentation. So i decided to do a ALTER TABLE dbo.myTable REBUILD Funny enough, afterwards i had 20% fragmentation. There was no write ...
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2answers
2k views

Does Clustered Index on GUID create more fragmentation than Non Clustered Index?

I have a simple table: CREATE TABLE [dbo].[UserTestGroups]( [UserTestGroupId] [int] IDENTITY(1,1) NOT NULL, [Token] [nvarchar](100) NOT NULL, [TestId] [bigint] NOT NULL, [Group] [...
3
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1answer
611 views

What is the impact of temporarily setting ALLOW_PAGE_LOCKS ON

The MSDN ALTER INDEX page says "An index cannot be reorganized when ALLOW_PAGE_LOCKS is set to OFF." I'm modifying our index reorg/rebuild process to be sensitive to indexes that have ...
1
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1answer
272 views

Optimising file shrink and index reorganization operations

I'm archiving my SQL tables. So I am shrinking my files (because I need the free space) and re-organising my indexes(to defragment them). I know shrinking a file causes the indexes to be fragmented. ...
15
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2answers
3k views

Can SQL Server system tables be defragmented?

We have several databases in which a large number of tables are created and dropped. From what we can tell, SQL Server does not conduct any internal maintenance on the system base tables, meaning that ...
1
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1answer
102 views

Effect of logical fragmentation of range scan in SQL Server Table

To the best of my knowledge, this is what happens during a range scan of a table for some data when the table has got a clustered index: The lower range is first found out, traced to the leaf node ...
3
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4answers
4k views

Index fragmentation increased significantly after rebuild

I've googled this and I know that some people say index fragmentation doesn't matter, but they go on to describe scenarios where it might matter. Mine might be such a scenario. I have an index on a ...
2
votes
1answer
800 views

SQL Server Index, difference between Average fragmentation and Total fragmentation

Using SQL server, If i navigate to a table in the object explorer, go to its indexes, go to its properties, and view the fragmentation tab, the top section has 2 lines for me, the Page fullness in ...
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1answer
215 views

Verify this TSQL to find the indexes fragmented over 50%

select OBJECT_SCHEMA_NAME(IPS.object_id) 'schema', OBJECT_NAME(IPS.object_id) as table_name,index_type_desc, round(avg_fragmentation_in_percent,2) 'avg_fragmentation_in_percent', si.name ...
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3answers
2k views

Manually create index fragmentation

Does anybody have a good approach to manually create a specific fragmentation to an index, ideally without increasing the number of rows in the underlying table? I need this for the purpose of a ...
5
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5answers
5k views

Does index rebuild time depend on the fragmentation level?

Is the required time for index rebuild dependent on the level of fragmentation? Does the rebuild of a 80% fragmented index approximately take 2 minutes if the rebuild of the same index fragmented 40%...
3
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1answer
771 views

Datetime Clustered Index Keeps getting fragmented

I have a large table (4 million Records) named CDR, which is used for storing CDRs (Call Detail Record)s from a Cisco router in a VoIP system, the table is constantly growing and will never have a ...
2
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4answers
3k views

What is the cause of high index fragmentation in SQL server?

We have an application which is using a SQL Server database. As the application is in use for many years, its database is of huge size, resulting in slowness of application. It was noticed that the ...