Data engineering·Modelling for analysis
the table has four hundred columns, most queries read six of them, and nobody can tell you what the other three hundred and ninety-four are for.
Wide table
Also calledwide schema, hundreds of columns
A table with a very large number of columns, which columnar formats make cheap to read from and expensive to understand. The performance argument against width mostly disappeared with column pruning; the comprehension argument did not, and neither did the write cost of rewriting every column when one changes. Width is now a documentation and ownership problem rather than a query problem.