22 votes
Accepted

How to lower HEAP Fragmentation in SQL Server?

What does Fragmentation Means in a Heap The fragmentation value in Heap which you get from column avg_fragmentation_in_percent by querying sys.dm_db_index_physical_stats DMV states that Logical ...
Shanky's user avatar
  • 19k
15 votes
Accepted

Index fragmentation problem after disabling page-level locking for an Index

The answer to your query is buried in some documentation: Online index rebuilding may increase fragmentation when it is allowed to run with MAX DOP > 1 and ALLOW_PAGE_LOCKS = OFF options. The ...
Josh Darnell's user avatar
  • 29.2k
11 votes
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Can SQL Server system tables be defragmented?

Are you sure you have positively and accurately identified this system table as the sole source of "unnecessary pressure on the buffer pool and also negatively impacts the performance of operations ...
Aaron Bertrand's user avatar
11 votes
Accepted

Fragmentation Level for Heaps

Heaps have a few special challenges that you can't experience with clustered indexes: Forwarded Records Captive Pages I'd suggest running sp_BlitzIndex against your database to find out if either of ...
Erik Darling's user avatar
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11 votes
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How likely is fragmentation on a table with 40000 products likely to affect performance

Based on the data that you have provided - there are 67 total pages. Index fragmentation for such a small table would not affect the performance. I would not worry about index fragmentation for the ...
Kin Shah's user avatar
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9 votes
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Does Clustered Index on GUID create more fragmentation than Non Clustered Index?

Since you are indicating insert performance is the primary concern, I'd take the recommendation of the DBA and make the clustering key the identity column since it is a unique, monotonically ascending ...
Hannah Vernon's user avatar
  • 69.9k
9 votes

Can SQL Server system tables be defragmented?

Based on guidance from Aaron's answer as well as additional research, here is a quick write-up of the approach I took. From what I can tell, the options for inspecting fragmentation of system base ...
Geoff Patterson's user avatar
9 votes

Fragmentation in PostgreSQL 9.1

Fragmentation is often called bloat in PostgreSQL. It relates to its implementation of MVCC where rows are not updated in place or directly deleted, but are copied with a different ID. Those rows are ...
KookieMonster's user avatar
8 votes

Does index rebuild time depend on the fragmentation level?

For everyone interested, I have created a chart showing the index REBUILD duration of about 2500 index rebuilds within couple of weeks in relation to the fragmentation of the index and it's size in ...
Magier's user avatar
  • 4,777
8 votes
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Table Fragmentation

Ola Hallengren's index optimize script does not perform Heap defragmentation. In other words table rebuilds are not happening when running the procedure and that is expected. You could run ALTER ...
Randi Vertongen's user avatar
7 votes
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Non-Unique Clustered Indexes Administration

This one is hard to answer without knowing your query patterns, but you will most definitely cause side effects when dropping all clustered indexes and replacing them with something else. I also don'...
Tom V's user avatar
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7 votes
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Table and Index fragmentation

You need to use INDEX_STATS view to determine fragmentation. Firstly, You need to populate this view with an individual index by using : SQL> analyze index <your_index> validate structure; ...
Barbaros Özhan's user avatar
7 votes

How big of a table or how many data pages in an index is worth considering running index rebuild or index reorganize operations on?

Also "reducing fragmentation" is not per se a performance goal. On many (most?) modern storage platforms there is little difference between sequential and random IO, which is a major historical ...
David Browne - Microsoft's user avatar
6 votes

SQL Server heap tables fragmentation monitoring

I would suggest that, rather than 'roll-your-own', you save yourself a whole bunch of time and effort and implement Ola Hallengren's Index Maintenance script. https://ola.hallengren.com/sql-server-...
Scott Hodgin - Retired's user avatar
6 votes
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Huge Heap Table and table compression on SQL Server 2016

Still i think that the table size is huge for the no. of records. Why? What makes you say this? what it does is stores different version of same entry from another table. So it holds versions, ...
Sean Gallardy's user avatar
6 votes

Indexes getting highly fragmented during normal usage of system

If you can properly confirm that fragmentation really is a problem, for example because read performance drops measurably when read-ahead becomes less effective, or because the system is struggling to ...
Paul White's user avatar
  • 83.7k
6 votes

Will I need to fix fragmentation after shrinking a database full of only HEAPs?

Will you need to? No. But consider replacing them with clustered columnstore tables with archive compression. They will be defragmented, smaller, and much faster to scan.
David Browne - Microsoft's user avatar
5 votes

Verify this TSQL to find the indexes fragmented over 50%

Your query has most of the main elements, but you are missing the important index_id join predicate from sys.dm_db_index_physical_stats to sys.indexes: AND si.index_id = IPS.index_id You might like ...
Paul White's user avatar
  • 83.7k
5 votes
Accepted

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

You should not update statistics after you rebuilt the index as rebuilding it gives you up-to-date statistics. See Does rebuild index update statistics? by Jack Li for more info. You get updated ...
Tara Kizer's user avatar
  • 5,936
5 votes
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Determining what objects SHRINKDATABASE will free space from

A few thoughts: 1. Never use SHRINKDATABASE, always use SHRINKFILE. You want to be in control of which file it is taking space from, and exactly how much so you leave some space in reserve. Run a ...
BradC's user avatar
  • 9,954
5 votes

Indexes getting highly fragmented during normal usage of system

Some options: Just update statistics You mentioned that fragmentation was causing performance issues. A lot of times it seems like fragmentation is the issue, when in reality the problem is bad ...
Josh Darnell's user avatar
  • 29.2k
5 votes
Accepted

How do we select fragmented indexes from postgresql?

You can use pgstatindex from the pgstattuple extension to get the leaf fragmentation of all B-tree indexes: SELECT i.indexrelid::regclass, s.leaf_fragmentation FROM pg_index AS i JOIN ...
Laurenz Albe's user avatar
  • 50.3k
5 votes

Index maintenance for AG DBs

You're not alone on seeing sync latency with AGs when doing index rebuilds. From Sean Gallardy's blog post SQL Server Index Maintenance – You’re Doing It Wrong (emphasis mine): In the worst of the ...
Josh Darnell's user avatar
  • 29.2k
4 votes
Accepted

Optimising file shrink and index reorganization operations

Move your indexes into a new pre-sized (but fairly small) filegroup. Moving them will involve a rebuild, and your file will be small. If you do this to all the objects in your current filegroup you ...
Rob Farley's user avatar
  • 16.2k
4 votes

Index with high fragmentation percentage

Short definition of Index Reorganize, made by Kendra Little: Reorganize: This option is more lightweight. It runs through the leaf level of the index, and as it goes it fixes physical ordering of ...
Marcin S.'s user avatar
  • 723
4 votes
Accepted

SQL Server Index, difference between Average fragmentation and Total fragmentation

There's a big difference between your query and the query the UI sends (which you can spy on using server-side trace, Extended Events, etc). In yours, the last argument to sys....
Aaron Bertrand's user avatar
4 votes
Accepted

Effect of logical fragmentation of range scan in SQL Server Table

Can someone tell me why? Why is the physical order important at all? Please note, I am speculating as to why the decisions were made given the best possible information I have available to me. AFAIK ...
Sean Gallardy's user avatar
4 votes
Accepted

Does index rebuild time depend on the fragmentation level?

I know that it's old thread, but I think it will be beneficial to share Paul Randal's post here. Algorithm Speed An index rebuild will always build a new index, even if there’s no ...
Elvin Ahmadov's user avatar
4 votes

DataBase Performance Issues with Indexes

Fill factor will leave free space on your index pages. If you know that updates on index keys will need aditional space, then it may be ok to leave that 10% free. But if there will be no changes on ...
Pablo Javier's user avatar
4 votes

How likely is fragmentation on a table with 40000 products likely to affect performance

Indices are bound to fragment in course of usage (time). What matters is if it is affecting the performance. Usually we do not worry about of indices with page_count < 500. (We as in, my team)...
Ramakant Dadhichi's user avatar

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