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Use SQL EXPLAIN to understand when and why indexes are used (or not).
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An in-depth overview of INSERT, SELECT, UPDATE, and DELETE statements,
ORDER BY, INNER JOIN, LEFT OUTER JOIN, WHERE, GROUP BY, and HAVING clauses,
and topics such as join tables and sub-queries.
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Calculations across objects are ripe for using a map and an inject but frequently, with ActiveRecord, the solution is more elegant and faster if we can have SQL do the work instead.
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How moving some data out of the database and into your codebase
as well-named constants can decouple your code and improve performance.
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Thoughts on safe indexes to add to Rails app databases.
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Sometimes in an app you need to do something in SQL and not in your app’s...
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Database normalization, the database world’s equivalent of DRY, can lead you...