DBAs from the client’s organization ended up an argument about how T-SQL works. The discussion was about the epic confusion about TOP and DISTINCT.
SQL Server emergency? Email pinal@sqlauthority.com with URGENT in the subject line.
DDL in a Transaction: What Rolls Back and What Blocks
DDL in a transaction works in SQL Server: CREATE, ALTER and DROP roll back like any other change. This post proves it with a small demo, lists the statements that are refused inside a transaction, and shows which locks an open DDL transaction holds and who has to wait for them.
Uniquifier: The Hidden Cost of Duplicate Clustered Keys
The uniquifier is a hidden 4-byte value that SQL Server adds to duplicate keys in a non-unique clustered index. This post measures its real cost row by row on SQL Server 2025 and shows it on the page. It also compares it with a unique key you choose yourself.
How to Write Efficient Query? – Interview Question of the Week #300
Question: How to Write Efficient Query?
Answer: There is no right or wrong answer to this question. Let us learn about it today.
Rewriting Correlated Subqueries as Window Functions
Replace correlated subqueries with windowed counts, dates, and running totals, preserve detail rows, and keep useful EXISTS filters.
Performance Challenge – Write Efficient Query – SQL in Sixty Seconds #140
Recently while working with my client I ended up in a very interesting situation where my client wanted me to write an Efficient Query.
SQL SERVER – Fix Error 8632 – Internal Error: An expression Services Limit Has Been Reached
When we tried to run a few of their stored procedure. How we can fix Error 8632 – Internal Error: An expression Services Limit Has Been Reached.
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