Waits since restart show where a SQL Server spends its waiting time. One query ranks the real waits, removes the idle ones, and adds the average wait, the signal share and a rate per hour of uptime. A table maps the common waits to the area to check next.
COUNT(*), COUNT(column) and COUNT(DISTINCT): Basics That Trip People
Why do two counts of the same table disagree? Five tiny demos show NULL, blank text, LEFT JOIN placeholders, bigint and join multiplication.
Ten Plan Operators Explained: An Operator Cheat Sheet
Seek, scan, lookup, three joins, sort, aggregate, spool and parallelism, each shown with a tiny demo. Learn to judge a plan by rows and executions.
SQL SERVER – Find Untrusted Foreign Key
An Untrusted Foreign key has not validated all existing rows. A customer bulk-load history prompted this inventory.
RESOURCE_SEMAPHORE vs THREADPOOL: Two Waits, Two Fixes
RESOURCE_SEMAPHORE vs THREADPOOL tells you whether a task waits for memory or for a worker thread. This post reads both counters and checks for live waits. A demo shows how an index shrinks a memory grant from 38,216 KB to zero.
Index Build Speed: Which Rebuild Settings Change the Time
Index build speed depends on rebuild or reorganize, MAXDOP, ONLINE, SORT_IN_TEMPDB and the recovery model. This post times each choice on a million row table and measures the log under each recovery model. It shows which one changes the clock and which changes only the log.
Forwarded Records, Multiple Backup and SSMS – SQL in Sixty Seconds – Feb 2021
This month’s SQL in Sixty Seconds topics were Forwarded Records, Multiple Backup and SSMS. Here are the videos released in Feb 2021.