Interview Q&A / SQL & DBMS
SQL & DBMS interview questions
Joins, keys, normalisation, indexes and transactions for placement and backend interviews.
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- What is a composite index and what is the leftmost prefix rule?
A composite index covers several columns in a fixed order. It can be used for queries filtering on its leading columns, such as (a) or (a, b), but generally not for a filter on b alone.
IntermediateQuick answer1 min read