def __str__(self):
"""
Prints Expectation of feature for conditions.
E(feature | c_1 Λ… Λc_n) (norm by multipliers).
"""
formula = " * E("
# features
for i, (table, multiplier) in enumerate(self.features):
formula += table + "." + multiplier
if i < len(self.features) - 1:
formula += "*"
# /(multipliers)
if len(self.normalizing_multipliers) > 0:
formula += " /("
# 1/multiplier
for i, (table,
normalizer) in enumerate(self.normalizing_multipliers):
formula += table + "." + normalizer
if i < len(self.normalizing_multipliers) - 1:
formula += "*"
formula += ")"
# |c_1 Λ… Λc_n
if len(self.conditions) > 0:
formula += "| "
formula += print_conditions(self.conditions)
formula += ")"
return formula
def true_cardinality(self, query):
full_join_query = gen_full_join_query(self.schema_graph, query.relationship_set, query.table_set, "JOIN")
where_cond = print_conditions(query.conditions, seperator='AND')
if where_cond != "":
where_cond = "WHERE " + where_cond
sql_query = full_join_query.format("COUNT(*)", where_cond)
cardinality = self.db_connection.get_result(sql_query)
return sql_query, cardinality
def __str__(self):
"""
Prints Probability of conditions
"""
formula = ""
if len(self.conditions) > 0:
formula += " * P("
formula += print_conditions(self.conditions)
formula += ")"
return formula
def __str__(self):
"""
Prints Expectation of multipliers for conditions.
E(multipliers * 1_{c_1 Λ… Λc_n})
"""
if self.inverse:
formula = " / E("
else:
formula = " * E("
for i, (table, normalizer) in enumerate(self.nominator_multipliers):
formula += table + "." + normalizer
if i < len(self.nominator_multipliers) - 1:
formula += "*"
if len(self.nominator_multipliers) == 0:
formula += "1"
if len(self.denominator_multipliers) > 0:
formula += "/("
# 1/multiplier
for i, (table,
normalizer) in enumerate(self.denominator_multipliers):
formula += table + "." + normalizer
if i < len(self.denominator_multipliers) - 1:
formula += "*"
formula += ")"
# |c_1 Λ… Λc_n
if len(self.conditions) > 0:
formula += "* 1_{"
formula += print_conditions(self.conditions)
formula += "}"
formula += ")"
return formula
def print_conditions(self, seperator='Λ'):
return print_conditions(self.conditions, seperator=seperator)