Try avoiding SELECT * even on single-column tables. Just keep that in mind even if you disagree. By the end of this article, I might have you contemplate. This is a true story I ran into with a…

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Hussein Nasser

Avoid using SELECT * in SQL queries, even for single-column tables, as it can lead to inefficient database operations and performance issues. Explicitly selecting only necessary columns allows for better optimization, reducing overhead related to deserialization, network costs, and query unpredictability. Specific column selection also facilitates easier code maintenance and database schema updates.

Avoid SELECT *, even on a single-column tables

Never thought that an innocent * could make such a mess! I will keep it in mind.

Title: “Avoid using SELECT *!”
Article: “We had a table with 3 blob fields, each containing a pretty big file.”
Such clickbait, wow.

I thought that it was obvious to everyone that reading 100 columns when you need 5 is going to require the database to read more data: usually from disk for large enough tables or worse network if using something like Hive on hdfs. Nevermind the amount of index/partition/etc based optimizations that will be avoided because the database optimizer “thinks” you need 100 columns.

I think that most popular ORMs account for this. If I were to write a manual query in one of my projects its because that query is the only way to get specific data in a reasonable time / space. I’ve looked at queries generated by both Hibernate and TypeORM and I’ve not seen SELECT *.