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More type safety

master
Salvo 'LtWorf' Tomaselli 2020-06-14 22:54:58 +07:00
parent 16459868cf
commit e35fc0f4bd
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GPG Key ID: B3A7CF0C801886CF
1 changed files with 26 additions and 7 deletions
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33
relational/optimizations.py
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@ -195,7 +195,7 @@ def futile_renames(n: parser.Node) -> Tuple[parser.Node, int]:
or removes the operation entirely if they all get removed
'''
if n.name == RENAME:
if isinstance(n, Unary) and n.name == RENAME:
renames = n.get_rename_prop()
changes = False
for k, v in renames.items():
@ -217,7 +217,10 @@ def subsequent_renames(n: parser.Node) -> Tuple[parser.Node, int]:
into
ρ ... (A)
'''
if n.name == RENAME and n.child.name == RENAME:
if isinstance(n, Unary) and \
n.name == RENAME and \
isinstance(n.child, Unary) and \
n.child.name == RENAME:
# Located two nested renames.
prop = n.prop + ',' + n.child.prop
child = n.child.child
@ -296,7 +299,10 @@ def swap_rename_projection(n: parser.Node) -> Tuple[parser.Node, int]:
Will also eliminate fields in the rename that are cut in the projection.
'''
if isinstance(n, Unary) and n.name == PROJECTION and n.child.name == RENAME:
if isinstance(n, Unary) and \
n.name == PROJECTION and \
isinstance(n.child, Unary) and \
n.child.name == RENAME:
# π index,name(ρ id➡index(R))
renames = n.child.get_rename_prop()
projections = set(n.get_projection_prop())
@ -329,7 +335,10 @@ def swap_rename_select(n: parser.Node) -> int:
Renaming the attributes used in the
selection, so the operation is still valid.'''
if isinstance(n, Unary) and n.name == SELECTION and n.child.name == RENAME:
if isinstance(n, Unary) and \
n.name == SELECTION and \
isinstance(n.child, Unary) and \
n.child.name == RENAME:
# This is an inverse mapping for the rename
renames = {v: k for k, v in n.child.get_rename_prop().items()}
@ -355,8 +364,11 @@ def select_union_intersect_subtract(n: parser.Node) -> int:
and replaces them with
σ (i OR q) (a)
Removing a O(n²) operation like the union'''
if n.name in {UNION, INTERSECTION, DIFFERENCE} and \
if isinstance(n, Binary) and \
n.name in {UNION, INTERSECTION, DIFFERENCE} and \
isinstance(n.left, Unary) and \
n.left.name == SELECTION and \
isinstance(n.right, Unary) and \
n.right.name == SELECTION and \
n.left.child == n.right.child:
@ -388,7 +400,12 @@ def union_and_product(n: parser.Node) -> Tuple[parser.Node, int]:
A * B ∪ A * C = A * (B ∪ C)
Same thing with inner join
'''
if n.name == UNION and n.left.name in {PRODUCT, JOIN} and n.left.name == n.right.name:
if isinstance(n, Binary) and \
n.name == UNION and \
isinstance(n.left, Binary) and \
n.left.name in {PRODUCT, JOIN} and \
isinstance(n.right, Binary) and \
n.left.name == n.right.name:
if n.left.left == n.right.left or n.left.left == n.right.right:
l = n.left.right
@ -429,7 +446,9 @@ def selection_and_product(n: parser.Node, rels: Dict[str, Relation]) -> parser.N
σ l (σ j (R) * σ i (Q)). Where j contains only attributes belonging to R,
i contains attributes belonging to Q and l contains attributes belonging to both'''
if isinstance(n, Unary) and n.name == SELECTION and n.child.name in (PRODUCT, JOIN):
if isinstance(n, Unary) and n.name == SELECTION and \
isinstance(n.child, Binary) and \
n.child.name in (PRODUCT, JOIN):
l_attr = n.child.left.result_format(rels)
r_attr = n.child.right.result_format(rels)