What is a clean buffer in DBCC DROPCLEANBUFFERS? No one had asked me this in 20 years, so here is the answer in the simplest words I could find.
How to Extract Alphanumeric Only From A String? – Interview Question of the Week #214
A reader wanted only the values that mix letters and numbers from a column. Here is how to extract alphanumeric values from a string with simple pattern matching.
How to Find Table Cardinality from the Execution Plan? – Interview Question of the Week #213
How to find table cardinality from the execution plan? I answer this health check question in two different ways, using a simple AdventureWorks query.
What is Consolidation of Index? – Interview Question of the Week #212
What is consolidation of index? When a table has overlapping indexes, like one on Col1 and one on Col1, Col2, here is how I think about combining them.
Does Parallel Threads Process Equal Rows? – Interview Question of the Week #211
Do parallel threads process equal rows? Usually no, and a simple AdventureWorks query with its actual execution plan proves it in a few seconds.
What is Trusted Constraint in SQL Server? – Interview Question of the Week #210
What is a trusted constraint in SQL Server? Many experts do not know, so instead of a definition I explain it with a simple check constraint example.
Does NOLOCK Really Applies No Lock? – Interview Question of the Week #209
Does NOLOCK really applies no lock? No. NOLOCK takes a Sch-S, or schema stability, lock. Here is a simple script to see it for yourself.