When Page Prefetching Takes a Back Seat – Exploring Trace Flag 652 in SQL Server
Learn how a trace flag affects SQL Server reading from disk and where this might be a useful thing for you to enable.
2025-09-24
2,506 reads
SQL Server internal storage
2025-05-16
624 reads
2025-01-15
1,860 reads
What happens when we drop a column on a SQL Server table? Where's my space?
You have dropped a column and wondering why you haven't recovered any space? Let's take a look.
2024-08-01 (first published: 2024-04-26)
4,916 reads
Identify Tables With Dropped Columns
How easily can we find tables with dropped columns that need cleanup?
2024-06-07
2,576 reads
2024-04-10
458 reads
Understanding CRUD Operations on Tables with B-tree Indexes, Page-splits, and Fragmentation
Introduction Every DML transaction reads the data before it makes any changes. Not only during a SELECT query, but when you run any DML statement, insert, update, or delete, SQL Server first fetches a bunch of pages into the buffer pool locating the desired rows and changes them while synchronously writing to the transaction log […]
2021-05-10
8,628 reads
Understanding CRUD Operations Against Heaps and Forwarding Pointers
In this article, we examine how data changes are made against heaps.
2021-05-03
4,857 reads
Understanding the Internals of a Data Page
In Part 1 of this series, we examine the structure of data pages and how your tables are stored on these pages.
2021-04-13
20,560 reads
2020-06-26
646 reads
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Question of the Day
Changing the Schema
I set up a few users on my SQL Server 2022 instance.
CREATE LOGIN User1 WITH PASSWORD = 'Demo12#1' CREATE USER User1 FOR LOGIN User1 GO CREATE LOGIN User2 WITH PASSWORD = 'Demo12#2' CREATE USER User2 FOR LOGIN User2 GO CREATE LOGIN User3 WITH PASSWORD = 'Demo12#3' CREATE USER User3 FOR LOGIN User3 GOI then created a schema that one of them owned. Under this schema, I added a table with some data.
CREATE SCHEMA MySchema AUTHORIZATION User1
GO
CREATE TABLE Myschema.MyTable(myid INT)
GO
INSERT MySchema.MyTable
(
myid
)
VALUES
(1), (2), (3)
GO
SELECT * FROM MySchema.MyTable
GO
I granted rights and verified that User2 could access this table.
GRANT SELECT ON Myschema.MyTable TO User2 GO SETUSER 'USER2' GO SELECT * FROM MySchema.MyTable GOThis worked. Now, I move this schema to a new user.
ALTER AUTHORIZATION ON SCHEMA::Myschema TO User3; GOWhat happens with this code?
SETUSER 'USER2' GO SELECT * FROM MySchema.MyTable GOSee possible answers