71 lines
2.6 KiB
Python
71 lines
2.6 KiB
Python
import itertools
|
|
|
|
from sqlglot import alias, exp
|
|
from sqlglot.helper import csv_reader
|
|
from sqlglot.optimizer.scope import Scope, traverse_scope
|
|
|
|
|
|
def qualify_tables(expression, db=None, catalog=None, schema=None):
|
|
"""
|
|
Rewrite sqlglot AST to have fully qualified tables.
|
|
|
|
Example:
|
|
>>> import sqlglot
|
|
>>> expression = sqlglot.parse_one("SELECT 1 FROM tbl")
|
|
>>> qualify_tables(expression, db="db").sql()
|
|
'SELECT 1 FROM db.tbl AS tbl'
|
|
|
|
Args:
|
|
expression (sqlglot.Expression): expression to qualify
|
|
db (str): Database name
|
|
catalog (str): Catalog name
|
|
schema: A schema to populate
|
|
Returns:
|
|
sqlglot.Expression: qualified expression
|
|
"""
|
|
sequence = itertools.count()
|
|
|
|
next_name = lambda: f"_q_{next(sequence)}"
|
|
|
|
for scope in traverse_scope(expression):
|
|
for derived_table in scope.ctes + scope.derived_tables:
|
|
if not derived_table.args.get("alias"):
|
|
alias_ = f"_q_{next(sequence)}"
|
|
derived_table.set("alias", exp.TableAlias(this=exp.to_identifier(alias_)))
|
|
scope.rename_source(None, alias_)
|
|
|
|
for source in scope.sources.values():
|
|
if isinstance(source, exp.Table):
|
|
identifier = isinstance(source.this, exp.Identifier)
|
|
|
|
if identifier:
|
|
if not source.args.get("db"):
|
|
source.set("db", exp.to_identifier(db))
|
|
if not source.args.get("catalog"):
|
|
source.set("catalog", exp.to_identifier(catalog))
|
|
|
|
if not source.alias:
|
|
source = source.replace(
|
|
alias(
|
|
source.copy(),
|
|
source.this if identifier else next_name(),
|
|
table=True,
|
|
)
|
|
)
|
|
|
|
if schema and isinstance(source.this, exp.ReadCSV):
|
|
with csv_reader(source.this) as reader:
|
|
header = next(reader)
|
|
columns = next(reader)
|
|
schema.add_table(
|
|
source, {k: type(v).__name__ for k, v in zip(header, columns)}
|
|
)
|
|
elif isinstance(source, Scope) and source.is_udtf:
|
|
udtf = source.expression
|
|
table_alias = udtf.args.get("alias") or exp.TableAlias(this=next_name())
|
|
udtf.set("alias", table_alias)
|
|
|
|
if not table_alias.name:
|
|
table_alias.set("this", next_name())
|
|
|
|
return expression
|