This PR speeds up drop construction and compilation in cases where the
number
of dropped columns is small relative to the total number of parent-table
columns.
There are two ways this is done:
- `drop` construction is sped up by reducing the number of iterations
over the full set of columns when constructing an output schema.
This is where the bulk of the improvement is.
- Compilation of the `drop` operation is also a bit faster for smaller
sets of
dropped columns on some backends due to use of `* EXCLUDE` syntax.
Since the optimization is done in the `schema` property, adding a new
`DropColumns` relation IR seemed like the lightest weight approach given
that that also enables compilers to use `EXCLUDE` syntax, which will
produce a
far smaller query than using project-without-the-dropped-columns
approach.
Partially addresses the `drop` performance seen in #9111.
To address this for all backends, they either need to all support
`SELECT * EXCLUDE(col1, ..., colN)` syntax or we need to implement
column
pruning.
Follow-ups could include applying a similar approach to `rename` (using
`REPLACE`
syntax for compilation).
It might be possible to reduce the overhead of `relocate` as well, but
I haven't explored that.
