Major Description
The getAliasedConstraints fuction in LogicalPlan.scala will clone the expression set when an element added,
and it will take a long time.
Before modified, the cost of getAliasedConstraints is:
100 expressions: 41 seconds
150 expressions: 466 seconds
The test is like this:
test("getAliasedConstraints") {
val expressionNum = 150
val aggExpression = (1 to expressionNum).map(i => Alias(Count(Literal(1)), s"cnt$i")())
val aggPlan = Aggregate(Nil, aggExpression, LocalRelation())
val beginTime = System.currentTimeMillis()
val expressions = aggPlan.validConstraints
println(s"validConstraints cost: ${System.currentTimeMillis() - beginTime}ms")
// The size of Aliased expression is n * (n - 1) / 2 + n
assert( expressions.size === expressionNum * (expressionNum - 1) / 2 + expressionNum)
}