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Why SELECT * is bad for SQL performance
- TedDoesntTalk 6y agoThis is the hardest one habit for even the most experienced developers to break. Just write count(id) instead!
- SigmundA 6y agoIn every dbms I have used count(*) is optimized to just count rows a fast as possible. count(column name) might actually be slower as it has to check for null values. Same goes for EXISTS(select * from table) I have seen many use count(1) and EXISTS (select 1 from table) this is mostly superstition and ends up getting optimized to the same as * at least now days.