> so queries like select a where b = 'x' are very quick
I wouldn’t say “very quick”. They only need to read and look at the data for columns a and b, whereas, with a row-oriented approach, with storage being block-based, you will read additional data, often the entire dataset.
That’s faster, but for large datasets you need an index to make things “very quick”. This format supports that, but whether to have that is orthogonal to being row/column oriented.
I wouldn’t say “very quick”. They only need to read and look at the data for columns a and b, whereas, with a row-oriented approach, with storage being block-based, you will read additional data, often the entire dataset.
That’s faster, but for large datasets you need an index to make things “very quick”. This format supports that, but whether to have that is orthogonal to being row/column oriented.