Running sp_configure and getting back a success message is not the same thing as a setting actually taking effect. Between the moment a value is changed and the moment SQL Server is actually running it sits a gap — one a busy DBA can close with a single RECONFIGURE, or forget entirely until a restart months later flips …

Not every plan in SQL Server's cache earns its place. A query compiled once — because its literal values were hard-coded into the text instead of passed as parameters — gets a full compiled plan cached right alongside plans an application reuses thousands of times a day. sys.dm_exec_cached_plans is where that …

A transaction that never commits keeps every log record written after it pinned in place, no matter how much work piles up behind it. sys.dm_tran_active_transactions lists every transaction currently open on the instance, but on its own it only shows a transaction ID and a start time — pairing it with …

Query Store buckets runtime statistics into fixed time intervals, which means a query that ran steadily all week doesn't produce one row of history — it produces one row per interval, split further by execution outcome. Averaging those rows unweighted is how a "most expensive queries" report quietly gets the ranking …

Buffer pool counters explain data cache pressure but go silent the moment memory trouble comes from somewhere else. sys.dm_os_memory_clerks is the DMV that covers everything the buffer pool doesn't — plan cache, In-Memory OLTP, Query Store, query memory grants, Extended Events sessions — by reporting pages_kb per …

sys.dm_os_buffer_descriptors is the DMV that maps SQL Server's data cache down to the individual page level — one row per 8 KB page currently held in the buffer pool, tagged with the database_id and file_id it belongs to. Rolling those rows up with a simple GROUP BY database_id turns millions of individual page entries …

I/O latency is where disk bottlenecks hide. SQL Server accumulates every millisecond of file-level read and write wait in sys.dm_io_virtual_file_stats — one row per database file, reset at each service restart. Joining that DMV to sys.master_files replaces raw file IDs with physical paths and file types, and dividing …

Knowing how much space each table and each index consumes is the foundation of capacity planning, archive policy, and index cleanup decisions on any SQL Server instance. This T-SQL script reads the partition-level storage statistics out of sys.dm_db_partition_stats and reports the size of every index — clustered, …

Running out of space inside a data or log file halts SQL Server transactions immediately — and discovering that a volume is full only after an outage is too late. This script queries sys.master_files and sys.dm_os_volume_stats across every online database on the instance to report each file's allocated size, space …

Finding databases that have not been backed up recently is one of the most important checks a DBA can run. A database that grows unnoticed without a backup is a data loss event waiting to happen. This script queries msdb.dbo.backupset against sys.databases to surface any online user database with no full backup in the …