The NULL Bitmap: How SQL Server Records Nullability
Every SQL Server data row carries a NULL bitmap, even a table with no nullable columns. Find it on the page, watch the bits flip as columns go NULL, and see what it actually costs.
How SQL Server Stores MONEY and SMALLMONEY, and the Rounding Trap
money and smallmoney are just integers scaled by 10000. The real page bytes, why the ranges are what they are, and the four-decimal truncation trap that bites calculations.
How SQL Server Stores DECIMAL and NUMERIC, Down to the Bytes
decimal and numeric store a sign byte plus a little-endian integer scaled by the column scale. Why precision buys storage in tiers, and why an oversized decimal is not free.
How SQL Server Stores a GUID, and Why Random Ones Fragment
A uniqueidentifier is 16 bytes with a peculiar sort order. Why random GUIDs fragment as a clustering key, and how NEWSEQUENTIALID and design fix it.
How SQL Server Stores Strings: varchar, nvarchar, and What UTF-8 Changed
The same word can take 3, 5, 6, or 9 bytes depending on the type and collation. A byte-level look at varchar, nvarchar, and UTF-8 collations.
SQL Server HA and DR Options: A Field Guide
Log shipping, replication, mirroring, FCIs, and Availability Groups compared: what each protects, sync vs async, failover, editions, and versions.