sqlglot.optimizer.qualify_tables
1from __future__ import annotations 2 3import itertools 4import typing as t 5 6from sqlglot import alias, exp 7from sqlglot._typing import E 8from sqlglot.dialects.dialect import DialectType 9from sqlglot.helper import csv_reader, name_sequence 10from sqlglot.optimizer.scope import Scope, traverse_scope 11from sqlglot.schema import Schema 12 13 14def qualify_tables( 15 expression: E, 16 db: t.Optional[str | exp.Identifier] = None, 17 catalog: t.Optional[str | exp.Identifier] = None, 18 schema: t.Optional[Schema] = None, 19 dialect: DialectType = None, 20) -> E: 21 """ 22 Rewrite sqlglot AST to have fully qualified tables. Join constructs such as 23 (t1 JOIN t2) AS t will be expanded into (SELECT * FROM t1 AS t1, t2 AS t2) AS t. 24 25 Examples: 26 >>> import sqlglot 27 >>> expression = sqlglot.parse_one("SELECT 1 FROM tbl") 28 >>> qualify_tables(expression, db="db").sql() 29 'SELECT 1 FROM db.tbl AS tbl' 30 >>> 31 >>> expression = sqlglot.parse_one("SELECT 1 FROM (t1 JOIN t2) AS t") 32 >>> qualify_tables(expression).sql() 33 'SELECT 1 FROM (SELECT * FROM t1 AS t1, t2 AS t2) AS t' 34 35 Args: 36 expression: Expression to qualify 37 db: Database name 38 catalog: Catalog name 39 schema: A schema to populate 40 dialect: The dialect to parse catalog and schema into. 41 42 Returns: 43 The qualified expression. 44 """ 45 next_alias_name = name_sequence("_q_") 46 db = exp.parse_identifier(db, dialect=dialect) if db else None 47 catalog = exp.parse_identifier(catalog, dialect=dialect) if catalog else None 48 49 for scope in traverse_scope(expression): 50 for derived_table in itertools.chain(scope.ctes, scope.derived_tables): 51 if isinstance(derived_table, exp.Subquery): 52 unnested = derived_table.unnest() 53 if isinstance(unnested, exp.Table): 54 joins = unnested.args.pop("joins", None) 55 derived_table.this.replace(exp.select("*").from_(unnested.copy(), copy=False)) 56 derived_table.this.set("joins", joins) 57 58 if not derived_table.args.get("alias"): 59 alias_ = next_alias_name() 60 derived_table.set("alias", exp.TableAlias(this=exp.to_identifier(alias_))) 61 scope.rename_source(None, alias_) 62 63 pivots = derived_table.args.get("pivots") 64 if pivots and not pivots[0].alias: 65 pivots[0].set("alias", exp.TableAlias(this=exp.to_identifier(next_alias_name()))) 66 67 for name, source in scope.sources.items(): 68 if isinstance(source, exp.Table): 69 if isinstance(source.this, exp.Identifier): 70 if not source.args.get("db"): 71 source.set("db", db) 72 if not source.args.get("catalog") and source.args.get("db"): 73 source.set("catalog", catalog) 74 75 if not source.alias: 76 # Mutates the source by attaching an alias to it 77 alias(source, name or source.name or next_alias_name(), copy=False, table=True) 78 79 pivots = source.args.get("pivots") 80 if pivots and not pivots[0].alias: 81 pivots[0].set( 82 "alias", exp.TableAlias(this=exp.to_identifier(next_alias_name())) 83 ) 84 85 if schema and isinstance(source.this, exp.ReadCSV): 86 with csv_reader(source.this) as reader: 87 header = next(reader) 88 columns = next(reader) 89 schema.add_table( 90 source, 91 {k: type(v).__name__ for k, v in zip(header, columns)}, 92 match_depth=False, 93 ) 94 elif isinstance(source, Scope) and source.is_udtf: 95 udtf = source.expression 96 table_alias = udtf.args.get("alias") or exp.TableAlias( 97 this=exp.to_identifier(next_alias_name()) 98 ) 99 udtf.set("alias", table_alias) 100 101 if not table_alias.name: 102 table_alias.set("this", exp.to_identifier(next_alias_name())) 103 if isinstance(udtf, exp.Values) and not table_alias.columns: 104 for i, e in enumerate(udtf.expressions[0].expressions): 105 table_alias.append("columns", exp.to_identifier(f"_col_{i}")) 106 107 return expression
def
qualify_tables( expression: ~E, db: Union[sqlglot.expressions.Identifier, str, NoneType] = None, catalog: Union[sqlglot.expressions.Identifier, str, NoneType] = None, schema: Optional[sqlglot.schema.Schema] = None, dialect: Union[str, sqlglot.dialects.dialect.Dialect, Type[sqlglot.dialects.dialect.Dialect], NoneType] = None) -> ~E:
15def qualify_tables( 16 expression: E, 17 db: t.Optional[str | exp.Identifier] = None, 18 catalog: t.Optional[str | exp.Identifier] = None, 19 schema: t.Optional[Schema] = None, 20 dialect: DialectType = None, 21) -> E: 22 """ 23 Rewrite sqlglot AST to have fully qualified tables. Join constructs such as 24 (t1 JOIN t2) AS t will be expanded into (SELECT * FROM t1 AS t1, t2 AS t2) AS t. 25 26 Examples: 27 >>> import sqlglot 28 >>> expression = sqlglot.parse_one("SELECT 1 FROM tbl") 29 >>> qualify_tables(expression, db="db").sql() 30 'SELECT 1 FROM db.tbl AS tbl' 31 >>> 32 >>> expression = sqlglot.parse_one("SELECT 1 FROM (t1 JOIN t2) AS t") 33 >>> qualify_tables(expression).sql() 34 'SELECT 1 FROM (SELECT * FROM t1 AS t1, t2 AS t2) AS t' 35 36 Args: 37 expression: Expression to qualify 38 db: Database name 39 catalog: Catalog name 40 schema: A schema to populate 41 dialect: The dialect to parse catalog and schema into. 42 43 Returns: 44 The qualified expression. 45 """ 46 next_alias_name = name_sequence("_q_") 47 db = exp.parse_identifier(db, dialect=dialect) if db else None 48 catalog = exp.parse_identifier(catalog, dialect=dialect) if catalog else None 49 50 for scope in traverse_scope(expression): 51 for derived_table in itertools.chain(scope.ctes, scope.derived_tables): 52 if isinstance(derived_table, exp.Subquery): 53 unnested = derived_table.unnest() 54 if isinstance(unnested, exp.Table): 55 joins = unnested.args.pop("joins", None) 56 derived_table.this.replace(exp.select("*").from_(unnested.copy(), copy=False)) 57 derived_table.this.set("joins", joins) 58 59 if not derived_table.args.get("alias"): 60 alias_ = next_alias_name() 61 derived_table.set("alias", exp.TableAlias(this=exp.to_identifier(alias_))) 62 scope.rename_source(None, alias_) 63 64 pivots = derived_table.args.get("pivots") 65 if pivots and not pivots[0].alias: 66 pivots[0].set("alias", exp.TableAlias(this=exp.to_identifier(next_alias_name()))) 67 68 for name, source in scope.sources.items(): 69 if isinstance(source, exp.Table): 70 if isinstance(source.this, exp.Identifier): 71 if not source.args.get("db"): 72 source.set("db", db) 73 if not source.args.get("catalog") and source.args.get("db"): 74 source.set("catalog", catalog) 75 76 if not source.alias: 77 # Mutates the source by attaching an alias to it 78 alias(source, name or source.name or next_alias_name(), copy=False, table=True) 79 80 pivots = source.args.get("pivots") 81 if pivots and not pivots[0].alias: 82 pivots[0].set( 83 "alias", exp.TableAlias(this=exp.to_identifier(next_alias_name())) 84 ) 85 86 if schema and isinstance(source.this, exp.ReadCSV): 87 with csv_reader(source.this) as reader: 88 header = next(reader) 89 columns = next(reader) 90 schema.add_table( 91 source, 92 {k: type(v).__name__ for k, v in zip(header, columns)}, 93 match_depth=False, 94 ) 95 elif isinstance(source, Scope) and source.is_udtf: 96 udtf = source.expression 97 table_alias = udtf.args.get("alias") or exp.TableAlias( 98 this=exp.to_identifier(next_alias_name()) 99 ) 100 udtf.set("alias", table_alias) 101 102 if not table_alias.name: 103 table_alias.set("this", exp.to_identifier(next_alias_name())) 104 if isinstance(udtf, exp.Values) and not table_alias.columns: 105 for i, e in enumerate(udtf.expressions[0].expressions): 106 table_alias.append("columns", exp.to_identifier(f"_col_{i}")) 107 108 return expression
Rewrite sqlglot AST to have fully qualified tables. Join constructs such as (t1 JOIN t2) AS t will be expanded into (SELECT * FROM t1 AS t1, t2 AS t2) AS t.
Examples:
>>> import sqlglot >>> expression = sqlglot.parse_one("SELECT 1 FROM tbl") >>> qualify_tables(expression, db="db").sql() 'SELECT 1 FROM db.tbl AS tbl' >>> >>> expression = sqlglot.parse_one("SELECT 1 FROM (t1 JOIN t2) AS t") >>> qualify_tables(expression).sql() 'SELECT 1 FROM (SELECT * FROM t1 AS t1, t2 AS t2) AS t'
Arguments:
- expression: Expression to qualify
- db: Database name
- catalog: Catalog name
- schema: A schema to populate
- dialect: The dialect to parse catalog and schema into.
Returns:
The qualified expression.