SQL Fundamentals
Composite Indexes: One Ordering, Not Three
Column order decides which queries a composite index can serve. The rule follows from the structure, and so do the cases where it does not hold.
· 3 min
tag
#indexing
Articles tagged “indexing” on SQLPress — 3 in total.
3 articles
MySQL
Why the Primary Key Is in Every Secondary Index
InnoDB stores the table inside its primary key. Almost every MySQL indexing consequence, good and bad, follows from that single decision.
· 3 min
PostgreSQL
Why an Index Is Not Used: the Estimate, Not the Index
An index the planner ignores is usually a row-estimate problem. The fix starts with what the optimizer expected, not with the index definition.
· 3 min