4 ms·
Basically select * loads the entire row at the DB end. This has no effect on disk load times when data is stored in pages but since this is result of query it m
by thecleaner 6y ago
Basically select * loads the entire row at the DB end. This has no effect on disk load times when data is stored in pages but since this is result of query it might get cached, might lead to more cache eviction and adds transfer overhead. Bottom line query what you need. Article is worth reading for the experimental setup used.
- jeltz 6y agoNope, SQL database can split large values over multiple pages so selecting and extra column can mean more dusk IO.
- thecleaner 6y agoI see so multiple page loads are also possible. Is the threshold documented ? Say for example for postgres ?
- anarazel 6y agohttps://www.postgresql.org/docs/devel/storage-toast.html https://www.postgresql.org/docs/devel/storage-toast.html