"It is difficult to cost - late materialisation can be a lot cheaper if there
are predicates"We can materialize the expression after the predicates is
executed. For example,select count(expr), sum(expr) from (select a+b+c
expr from T where a>10) T where T.expr>201. Scan column a and
execute a>1
"It is difficult to cost - late materialisation can be a lot cheaper if there
are predicates"We can materialize the expression after the predicates is
executed. For example,select count(expr), sum(expr) from (select a+b+c
expr from T where a>10) T where T.expr>201. Scan column a and
execute a>1
I agree in that scenario where predicates are pushed down to the scan. It
can be more of a trade-off if there are selective predicates later in the
plan, e.g. after a join or aggregation node - in that case it depends on
how expensive the expression is and how selective the predicates are.
I defin
