((install)): Guru Guide To Sql Server Architecture And Internals.pdf

Index stats were stale. The query optimizer thought the scan was cheaper because it didn’t know the table had grown massively since the last stats update.

The most complex diagrams in any usually involve memory architecture. SQL Server is memory-hungry, and for good reason. Guru Guide To Sql Server Architecture And Internals.pdf

The Buffer Pool is the main memory cache. It is where data pages live after being read from the disk. The goal of any database optimization is to keep as much data in the Buffer Pool as possible, because memory is nanosecond-fast, while disk is millisecond-fast. Index stats were stale

Every change is first written to the Transaction Log (LDF) before it is committed to the data file (MDF). This "Write-Ahead Logging" (WAL) ensures data integrity in the event of a crash. 4. Physical Architecture: Pages and Extents SQL Server is memory-hungry, and for good reason

SELECT last_user_seek, last_user_scan, modifications FROM sys.dm_db_index_usage_stats WHERE database_id = DB_ID('SalesDB') AND object_id = OBJECT_ID('Orders');

In SQL Server, the fundamental unit of data storage is the . Each page is 8 KB in size.