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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Index Fragmentation - log issues

I have a few questions that I want to understand in order to take informed decision. I am not a DBA by profession, I have done some administrative tasks in the past and now I would have to create a ...
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Is fragmentation at non-leaf levels a problem?

SQL version: 2017 Standard x64 OS: Windows Server 2016 Datacenter (10.0) I've just created some minimal indexes on ETL tables which were previously heaps with no indexes. Both R and W performance ...
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SQL Server - Very high disk activity after running query?

I'm running SQL Server Express 12.0.4100 on an AWS instance with 16 cores and 64 GB of RAM with a 3TB and 9000 IOPS EBS attached. This has been running for 2 years perfectly with no issues until this ...
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How big of a table or how many data pages in an index is worth considering running index rebuild or index reorganize operations on?

In the Books Online for Reorganize and Rebuild Indexes Microsoft mentions: Rebuilding or reorganizing small rowstore indexes often does not reduce fragmentation. What magnitude of number of rows ...
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Do I need to rebuild heap table after rebuilding a non-clustered index?

Assume that I have a heap table with a higher fragmentation percentage and that table also has a non-clustered index with higher fragmentation too. I can't reproduce this case right now but maybe ...
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IndexOptimize is successful, but sys.dm_db_index_physical_stats still shows huge fragmentation

I'm working on a project that requires a database shrink. Following the shrink, I checked sys.dm_db_index_physical_stats and can see a lot of my indexes are over 99% fragmented (...
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MongoDB Fragmentation affect the Performance in WiredTiger

Im using MongoDB 3.6 I have a huge number of fragmentation in my collections. 300+ GB on one collection. WiredTiger is the storage engine. I know its bad for the OS and much wasted space. This ...
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Problem with calculating an approximate space required for online index rebuild

I have a database called TestDB which is in simple recovery model. I performed index rebuild on my Test Server which has no other user transactions except me. Before an online index rebuild the sizes ...
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4answers
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Is fragmention limited to indexes in sql server?

As far as I can see with research the only thing that fragments is indexes no other objects in SQL can fragment. I have to keep track of fragmentation within multiple databases, would it be correct ...
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How likely is fragmentation on a table with 40000 products likely to affect performance

So database administration is not a strong point of mine, so I have a few questions. This all relates to the performance of a website I'm looking at, and have spent a fair bit of time researching/...
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34 views

Not lowering avg fragmentation

I have a script which iterates through all database and underlying tables. With this script i want to rebuild/reorganize the indexes and i am testing this on AdventureWorks2017 database. So after ...
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Index fragmentation problem after disabling page-level locking for an Index

I have an Index which has page level locking disabled and now I have index fragmentation issues for that index. I was aware that I won't be able to Reorganize the index, but I believed that I would ...
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Indexes getting highly fragmented during normal usage of system

I am using MS SQL Server 2014 Standard Edition in my project and recently I have encountered an issue with index fragmentation getting high during normal usage of the system by the users. Currently ...
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Huge Heap Table and table compression on SQL Server 2016

My database size is huge, and recently I noticed that a new table added few months ago is the culprit. Here is the table script. SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo]....
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Is this database fragmentation or something else? What can be done?

I have the table below in PostgreSQL (automagically generated with insertions using Marten): create table mt_doc_order ( id uuid ...
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3answers
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Query to see Index Fragmentation on all databases without using SP or temp tables

I am trying to compile a index fragmentation report on all databases, in a multi-server environment. The query will be executed via an openquery command, so I would like to make it as simple as ...
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69 views

Is there any way to find information of index fragmentation, Statistics information with the help of system tables in SQL Server

I am working on a report which will give information for different segments like blocking process slow running queries disk space etc. I also want to add one more segment where I can get ...
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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
478 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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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 ...
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486 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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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?
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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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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 ...
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191 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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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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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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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 ...
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468 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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Fragmentation in InnoDB tables: dump all data together reduced size, but fragmentation got worse [closed]

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
158 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 ...
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2answers
303 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
512 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 ...
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1answer
229 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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Fragmentation in PostgreSQL 9.1

How can I check for fragmentation in PostgreSQL 9.1?
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1answer
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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
498 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 ...
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1answer
964 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
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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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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
630 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
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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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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 ...
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1answer
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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" ...
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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 ...
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1answer
737 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 ...
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1answer
540 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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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
202 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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592 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 ...