This episode of SQL in Sixty seconds is very special as it contains 9 SQL SERVER Performance Tuning Tips. The length of the video is also longer.
Top Three Wait Stats and What Each One Means
The top three wait stats in the files people sent in were CXPACKET, SOS_SCHEDULER_YIELD and ASYNC_IO_COMPLETION. A small demo makes each wait happen and measures it with session wait statistics. The post explains what each one means and what to check next.
Internal Temporary Tables in MySQL: When a Query Spills to Disk
MySQL and MariaDB build internal temporary tables behind your back for GROUP BY, DISTINCT, UNION and derived tables. This post counts them with status counters, reads them in EXPLAIN, shows what pushes one to disk, and removes one with an index.
DMV Version of sp_who2: A Cleaner Session List
A DMV version of sp_who2 returns the same session details from documented views and leaves out the system tasks. This post builds the query, shows why the old spid above 50 filter fails, and stores the result in a temporary table.
SQL SERVER – Logical Processing Order of the SELECT Statement
Logical Processing places DISTINCT before TOP in a SELECT statement. Questions after my video prompted this explanation.
SQL SERVER – TOP and DISTINCT – Epic Confusion – SQL in Sixty Seconds #141
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.
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.