<ul><li>Using SELECT * means that the database optimizer cannot choose index-only scans.</li><li>The computational overhead of deserialization can slow down query performance.</li><li>Not all columns are stored inline, and retrieving large columns like blobs increases I/Os.</li><li>Before the query result is sent to the client, it is serialized according to the communication protocol supported by the database, which affects network latency.</li><li>Client apps must deserialize the data after they receive the raw bytes, adding to overall processing time.</li><li>Using SELECT * on the client side, even if the table has one or two fields, can introduce unpredictability.</li><li>Explicit SELECT makes it easier to grep the codebase for in-use columns and make database schema changes.</li><li>It’s generally best to only select necessary fields to reduce unnecessary overhead when querying tables.</li><li>However, for tables with few columns and simple data types, SELECT * overhead may be negligible.</li><li>Be selective about the columns retrieved in queries to improve overall query performance.</li></ul>

Avoid SELECT *, even on a single-column tables

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