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selection_inside_projection

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Salvo 'LtWorf' Tomaselli 2020-06-09 11:55:25 +02:00
parent 418e293c1d
commit 6622ba947e
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GPG Key ID: B3A7CF0C801886CF
1 changed files with 9 additions and 11 deletions
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20
relational/optimizations.py
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@ -202,20 +202,18 @@ def duplicated_projection(n: parser.Node) -> Tuple[parser.Node, int]:
return n, 0
def selection_inside_projection(n: parser.Node) -> int:
def selection_inside_projection(n: parser.Node) -> Tuple[parser.Node, int]:
'''This function locates things like σ j (π k(R)) and
converts them into π k(σ j (R))'''
changes = 0
if n.name == SELECTION and n.child.name == PROJECTION:
changes = 1
temp = n.prop
n.prop = n.child.prop
n.child.prop = temp
n.name = PROJECTION
n.child.name = SELECTION
child = parser.Unary(
SELECTION,
n.prop,
n.child.child
)
return changes + recoursive_scan(selection_inside_projection, n)
return parser.Unary(PROJECTION, n.child.prop, child), 0
return n, 0
def swap_union_renames(n: parser.Node) -> int:
@ -663,7 +661,7 @@ general_optimizations = [
duplicated_select,
down_to_unions_subtractions_intersections,
duplicated_projection,
#selection_inside_projection,
selection_inside_projection,
#subsequent_renames,
#swap_rename_select,
futile_union_intersection_subtraction,