Tag: Query Performance

Sometimes the old ways are still the best- even in technology. Long before there was an SQL Server, database professionals made advantageous use of the “covering” index, so-called because the columns used in the index cover all the requirements of a particular query of special interest. Let’s take a look at a class covering indexes […]

Is it Better or Worse? What is Cardinality Estimation A fancy-sounding phrase, “cardinality estimation” basically means “guessing how many”. The ability of the query optimizer to select a superior query plan from among many possibilities requires the estimation of how many rows will be extracted from the participating tables and how these rows will be […]