Delete qualified rows from multiple tables with as few logical reads as you can. This puzzle gives a setup script for three small tables, the two rules for the delete and a starting script that costs 19 logical reads. Your task is to beat that number and stay correct.
SCHEMA_ONLY vs SCHEMA_AND_DATA for Memory-Optimized Tables
Compare SCHEMA_ONLY and SCHEMA_AND_DATA memory-optimized tables, inspect logging and recovery, and test an isolated offline-online cycle.
DBCC DROPCLEANBUFFERS Impact on Memory: See a Cold Cache in Action
DBCC DROPCLEANBUFFERS removes every clean page from memory, so the next query reads from disk. This post counts the pages of one database before and after, shows why a CHECKPOINT comes first, and compares a cold read with a warm read.
PARALLEL_BACKUP_QUEUE Wait on a Slow RESTORE FILELISTONLY
A reader asked me what the PARALLEL_BACKUP_QUEUE wait means. Their RESTORE FILELISTONLY ran for a long time on a backup of about 1.5 TB and ended with a media error. I believe a problem with the backup media makes the command run long and shows this wait.
Sessionizing Events: Grouping Activity Into Sessions by Idle Gap
Your events have a user and a time but no visit ID. Here is how to infer sessions from an idle gap with LAG and a running sum.
Logical Name Mismatch: master_files vs database_files
A logical name mismatch means sys.master_files and sys.database_files disagree about a file name. A tested demo shows both views on one server, and a script checks every database. The post explains the secondary replica case and its fix.
What is Source_Database_ID in Sys.Databases?- Interview Question of the Week #232
Question: What is Source_Database_ID in Sys.Databases and why it is mostly NULL? Very interesting question, I received indeed.
sysxmitqueue in msdb: Why It Grows and How to Clear It
Sysxmitqueue in msdb fills up when Service Broker messages cannot leave the server. A tested demo in its own database shows the pile, the reason, a one conversation cleanup and the NEW_BROKER reset. The msdb steps follow the same order.
DBCC CLONEDATABASE Error Msg 2601: Cannot Insert Duplicate Key Row in sys.sysowners
A DBCC CLONEDATABASE error that names sys.sysowners points at a database user name, not at the database owner. The queries here find the conflicting user in model and in the source database, and I tested them on SQL Server 2025 along with a clean clone.
SQL SERVER – DBCC CLONEDATABASE Error: Cannot Insert Duplicate Key Row In Object ‘sys.sysschobjs’ With Unique Index ‘clst’.
Investigate a DBCC CLONEDATABASE sys.sysschobjs error with supported catalog checks, original screenshots and a distinct build-specific fix.