Downtime Caused by the Postgres Transaction ID Wraparound Problem
Learn about transaction ID wraparound in PostgreSQL, which caused a problem for the author.
2026-02-23 (first published: 2026-02-13)
1,787 reads
Learn about transaction ID wraparound in PostgreSQL, which caused a problem for the author.
2026-02-23 (first published: 2026-02-13)
1,787 reads
Learn about filtered indexes in SQL Server, how they work, and how they can help improve performance.
2025-11-24
4,064 reads
Learn about unlogged tables and how they work in PostgreSQL.
2025-11-21
4,764 reads
Learn about a MySQL feature that could be useful in some scenarios for SQL Server.
2025-11-10
4,257 reads
Learn about implicit transaction and why you might not want to enable this setting.
2025-10-24
6,478 reads
Learn how a setting an improve high concurrency inserts with the OPTIMIZE_FOR_SEQUENTIAL_KEY option.
2025-10-01
6,060 reads
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
2,464 reads
A look at window functions in SQL and how they can be used to query data without the restrictions of a GROUP BY.
2025-09-12
6,869 reads
Page splits are an often-overlooked performance killer in SQL Server. In this article, we take a forensic look at how serial inserts differ from mid-table inserts, revealing why inserting rows out of order causes hidden page splits, increased IO, and fragmentation. Using a wide-column table, we demonstrate both scenarios and decode their impact with page-level analysis.
2025-09-02 (first published: 2025-08-05)
2,540 reads
TEXT, NTEXT, and IMAGE columns have been deprecated for nearly two decades, yet they still silently haunt many SQL Server environments. This article explains their hidden limitations with practical demos and shows why migrating to VARCHAR(MAX), NVARCHAR(MAX), and VARBINARY(MAX) is critical for modern performance, maintainability, and future upgrades.
2025-09-02 (first published: 2025-08-06)
2,553 reads
By James Serra
I’m honored to be hosting T-SQL Tuesday — edition #192. For those who may...
By Vinay Thakur
Continuing from Day 2 , we learned introduction on Generative AI and Agentic AI,...
Quite the title, so let me set the stage first. You have an Azure...
hi everyone I am not sure how to write the query that will produce...
Comments posted to this topic are about the item Rollback vs. Roll Forward
Comments posted to this topic are about the item Foreign Keys - Foes or...
I have some data in a table:
CREATE TABLE #test_data
(
id INT PRIMARY KEY,
name VARCHAR(100),
birth_date DATE
);
-- Step 2: Insert rows
INSERT INTO #test_data
VALUES
(1, 'Olivia', '2025-01-05'),
(2, 'Emma', '2025-03-02'),
(3, 'Liam', '2025-11-15'),
(4, 'Noah', '2025-12-22');
If I run this query, how many rows are returned?
SELECT *
FROM OPENJSON(
(
SELECT t.* FROM #test_data AS t FOR JSON PATH
)
) t; See possible answers