Using Redundant Conditions to Unlock Indexes in MySQL

As the article notes,<p>&gt; Redundant conditions are nice because they require no changes to the database [...] This makes them useful for queries that are only sometimes run or where indexes can&#x27;t be easily added to the main conditions<p>but where possible I typically prefer adding an index on the expression that the query is using (if your database supports it) since it expresses your intent more clearly. A redundant condition is more likely to get &quot;optimized away&quot; by other developers or changes in the query planner.

The largest query I wrote was for estimating student loan repayments over a large time period. It solved a problem by running a dense 2 page query for 2 minutes in DB2 on a mainframe. The only way it ran at all was with many heuristic bounding conditions that limited the search space for the more specific conditions, as well as applying the most recent PTFs (patches) to increase query complexity limits. It wasn&#x27;t however at all maintainable so was legacy code from day one.

&gt; In this example, we could use a range scan instead of the YEAR function to obtain the same result.<p>The range scan will miss all items with a created_at from 2023-12-31 00:00:01 to 2023-12-31 23:59:59

Does this technique generally work with postgres as well?

At this point, doesn&#x27;t it make more sense to just throw away the original where condition and use only the redundant condition? If it&#x27;s really redundant and makes no different to the result, why keeping the inefficient clause be useful once the new&#x2F;better clause has been added?