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from sqlglot.optimizer.eliminate_subqueries import eliminate_subqueries
from sqlglot.optimizer.expand_multi_table_selects import expand_multi_table_selects
from sqlglot.optimizer.isolate_table_selects import isolate_table_selects
from sqlglot.optimizer.merge_derived_tables import merge_derived_tables
from sqlglot.optimizer.normalize import normalize
from sqlglot.optimizer.optimize_joins import optimize_joins
from sqlglot.optimizer.pushdown_predicates import pushdown_predicates
from sqlglot.optimizer.pushdown_projections import pushdown_projections
from sqlglot.optimizer.qualify_columns import qualify_columns
from sqlglot.optimizer.qualify_tables import qualify_tables
from sqlglot.optimizer.quote_identities import quote_identities
from sqlglot.optimizer.unnest_subqueries import unnest_subqueries
RULES = (
qualify_tables,
isolate_table_selects,
qualify_columns,
pushdown_projections,
normalize,
unnest_subqueries,
expand_multi_table_selects,
pushdown_predicates,
optimize_joins,
eliminate_subqueries,
merge_derived_tables,
quote_identities,
)
def optimize(expression, schema=None, db=None, catalog=None, rules=RULES, **kwargs):
"""
Rewrite a sqlglot AST into an optimized form.
Args:
expression (sqlglot.Expression): expression to optimize
schema (dict|sqlglot.optimizer.Schema): database schema.
This can either be an instance of `sqlglot.optimizer.Schema` or a mapping in one of
the following forms:
1. {table: {col: type}}
2. {db: {table: {col: type}}}
3. {catalog: {db: {table: {col: type}}}}
db (str): specify the default database, as might be set by a `USE DATABASE db` statement
catalog (str): specify the default catalog, as might be set by a `USE CATALOG c` statement
rules (list): sequence of optimizer rules to use
**kwargs: If a rule has a keyword argument with a same name in **kwargs, it will be passed in.
Returns:
sqlglot.Expression: optimized expression
"""
possible_kwargs = {"db": db, "catalog": catalog, "schema": schema, **kwargs}
expression = expression.copy()
for rule in rules:
# Find any additional rule parameters, beyond `expression`
rule_params = rule.__code__.co_varnames
rule_kwargs = {param: possible_kwargs[param] for param in rule_params if param in possible_kwargs}
expression = rule(expression, **rule_kwargs)
return expression
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