Questions tagged [page-splits]

The process of splitting a physical storage page in two or more pages to accommodate new or changed rows.

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4answers
95 views

Can lowering fill factor result in more page splits? [closed]

We've been having a problem with page splits on a table that is a particular nuisance - its an audit log of activities in the database and has grown over 1TB. The main indexes are on the record type, ...
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1answer
31 views

How to find if my innodb row uses overflow/off pages?

I use INNODB engine. My row format is Dynamic. For variable-length columns like TEXT, BLOB and varchar etc. , data is stored in off page and not in the same page itself. Do I have a way to ...
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1answer
32 views

Need some insights on 'index_page' variables in Innodb_Metrics Table

I was experimenting with page-split behaviour for sequencial vs random ordered inserts in Mysql,Innodb. For sequencial Inserts I got: index_page_splits: 3199 index_page_merge_attempts: 0 ...
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1answer
59 views

How are page splits determined internally in MySQL?

Going through this answer for a stack-overflow question, I found a fact that In The physical structure of InnoDB index pages I describe the Last Insert Position, Page Direction, and Number of ...
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1answer
26 views

Can an InnoDB page contain data from different indexes?

(In this question, I assume that the data of a table is acťually an index (PRIMARY), so I don't differentiate between table data and column indexes) I've compacted an "old" InnoDB table (via null ...
2
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1answer
77 views

Page Splits on an empty table

I have a monitoring tool that alerted me to high page splits, 50% of new allocations. After some Google Fu, I found the following query to look and see: SELECT IOS.index_id, O.NAME ...
2
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0answers
50 views

MSSQL Page Split Spike on AlwaysOn Readable Secondary

Recently I caught a massive page-split spike on an AlwaysOn Secondary instance that was not mimicked in any way by the active primary. I'm interested in what might cause this on a readable secondary ...
2
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1answer
51 views

Is it possible to get a “pages touched” statistic from PostgreSQL?

With PostgreSQL one can measure disk reads and cache hits. Is it possible to have a clearer statistic of how many index pages were "touched" to run a query? If so, how?
3
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1answer
760 views

Finding reason for page splits

So normally we have 20-85 Page splits/s but sometimes this spikes up the 700 - 2500 range. So to figure out what was happening i created a Extended Event with the following: CREATE EVENT SESSION ...
6
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1answer
842 views

Index Pages (page type 2)

I trying to understand page splits in SQL Server, reading WHAT IS A PAGE SPLIT? WHAT HAPPENS? WHY DOES IT HAPPEN? WHY WORRY? by Tony Rogerson CREATE TABLE mytest ( something_to_see_in_data ...
7
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1answer
510 views

MS SQL Page split confusion

I am a bit confused about page splits in MS SQL and I'm looking for a definitive answer. There seem to be two versions of the story: 1 - Fillfactor only affects how full pages are at the time the ...
0
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1answer
277 views

Is there a way to track page splits on an InnoDB table?

Is there a way to track the number of page splits on an InnoDB table? I've inherited a couple high-volume tables with integer primary keys in which values are often inserted out of order and I'd like ...
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0answers
54 views

Refactoring 80 GB table that stores massive amount of calculated results

Trying to evaluate architectural changes to improve the performance of an app that calculates a lot of individual values and stores each of these results as a row. The storage size for one of the ...
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2answers
949 views

Merits of inserting to temp table and renaming versus just adding/removing columns

If I add or drop columns from a SQL Server table I presume I get page splits or gaps. Since the size of the row has changed. When I use RedGate SQL Compare to create conversion scripts its strategy ...
0
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1answer
81 views

SQL Server 2000 Page Splits per second higher han 12 million?

I was reading about index fill factors & performance, and out on a whim I tried the query given by the webpage on the company's production SQL Server 2000 server: SELECT * FROM MASTER.dbo....
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2answers
524 views

Analyse what caused a pagesplit afterwards?

Ok normally we have 0-20 page splits per second, but last night it spiked to ~500. Now is there any way to figure out what caused it? I know i can run the following to find mid page splits but it ...
3
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1answer
445 views

Why only 8kb per page?

I just want to know how they came to 8kb when striking a balance between: smaller page = more page splits bigger page = longer to look through to find value I expect there are many more pros and cons ...
3
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2answers
13k views

Page Break is splitting in the middle of a single row in SSRS

I have an SSRS report for an Invoice and it generally works perfectly but occasionally it will page break in the middle of a row in the main Tablix. The row will split and leave part of the text on ...
3
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1answer
193 views

Page Split Timing

So, imagine I have a page that I intend to cause to split. USE master ; GO IF DATABASEPROPERTYEX (N'Pages', N'Version') > 0 BEGIN ALTER DATABASE Pages SET SINGLE_USER WITH ROLLBACK IMMEDIATE; ...
8
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1answer
1k views

B-tree node split strategy in SQL Server for monotonically increasing value

Consider a B-tree index on a value that will always increase monotonically, e.g. a column of type IDENTITY. With a conventional B-tree implementation, whenever a node is full, it will be split 50%/50% ...