Questions tagged [page-splits]
The process of splitting a physical storage page in two or more pages to accommodate new or changed rows.
21
questions
7
votes
1answer
130 views
Updating rows in Azure SQL Server causing unexpected page splits
I'm getting a lot of page splits in a live environment using Azure SQL Server PAAS that I don't understand. The update that's occurring should not increase the size of the row and therefore never ...
5
votes
4answers
153 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, ...
0
votes
1answer
242 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 ...
0
votes
1answer
75 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
...
1
vote
1answer
260 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 ...
0
votes
1answer
29 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 ...
1
vote
1answer
141 views
Page splits on an empty table
I have a monitoring tool that alerted me to high page splits, 50% of new allocations. I found the following query to look and see:
SELECT IOS.index_id,
O.NAME AS ...
2
votes
0answers
70 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
votes
1answer
84 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
votes
1answer
911 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 ...
7
votes
1answer
955 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 CHAR(...
8
votes
1answer
601 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
votes
1answer
346 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 ...
0
votes
0answers
58 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 ...
1
vote
2answers
1k 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
votes
1answer
89 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....
0
votes
2answers
565 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
votes
1answer
555 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
votes
2answers
14k 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
votes
1answer
202 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;
...
9
votes
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% ...
